Mica deposits of the Franklin-Sylva District, North Carolina

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NORTH CAROLINA
DEPARTMENT OF CONSERVATION AND DEVELOPMENT
R. BRUCE ETHERIDGE, DIRECTOR
DIVISION OF MINERAL RESOURCES
jasper L. stuckey, State geologist
Bulletin Number 49
MICA DEPOSITS OF THE FRANKLIN -SYLVA
DISTRICT, NORTH CAROLINA
By
J. C. OLSON
and Others
Prepared by Geological Survey, U. S. Department of the Interior
in cooperation with the
North Carolina Department of Conservation and Development
RALEIGH
1946
North Carolina
Department of Conservation and Development
R. Bruce Etheridge, Director
Division of Mineral Resources
Jasper L. Stuckey, State Geologist
Bulletin Number 49
MICA DEPOSITS OF THE FRANKLIN SYLVA
DISTRICT, NORTH CAROLINA
By
J. C. Olson
and Others
Prepared by Geological Survey, U. S. Department of the Interior
in cooperation with the
North Carolina Department of Conservation and Development
Raleigh
1946
MEMBERS OF THE BOARD OF CONSERVATION AND
DEVELOPMENT
Governor R. Gregg Cherry, Chairman Raleigh
J. L. Horne, Vice-Chairman Rocky Mount
Charles S. Allen Durham
Oscar P. Breece . Fayetteville
J. Wilbur Bunn Raleigh
K. Clyde Council Wananish
R. Floyd Crouse Sparta
W. J. Damtoft Canton
Percy B. Ferebee Andrews
A. H. Guion . Charlotte
W. Roy Hampton Plymouth
R. W. Proctor Marion
Miles J. Smith Salisbury
D. M. Stafford Pomona
A. K. Winget Albemarle
J. R. Wollett Littleton
R. Bruce Etheridge, Director
11
CONTENTS
Page
Letter of Transmittal vi
Preface vii
General summary, by J. C. Olson 1
Abstract 1
Introduction 1
Geography 2
•Field work and acknowledgments 4
Previous work 4
General geology 5
Metamorphic rocks 5
Weathering , 5
Igneous rocks 5
Coarse-grained granite 5
Other granite bodies 5
Dunite 6
Structure 6
Folds 6
Fractures 6
Pegmatites 7
Size and shape 7
Structure .'. 7
Wall-rock alteration 8
Mineralogy 8
Mineral distribution 9
Quartz cores 9
"Burr rock" 9
Border zones 10
Feldspathic pegmatite 10
Granite in pegmatite 10
Occurrences of muscovite 10
Disseminated mica . : 11
Mica related to quartz cores 11
Mica related to walls 12
Mica associated with granite bodies 13
Source and emplacement of pegmatite 13
in
CONTENTS
—
Continued
Page
Muscovite 13
Properties 13
Classification and grading 14
Qualitative distribution 15
Mining 15
History 15
Methods 16
Economic factors 16
Scrap mica : 17
Feldspar 17
Past production 17
Future possibilities 19
Descriptions of selected mines : 20
Allman Cove mine, by J. M. Parker III 20
Beasley No. 1 mine, by M. R. Klepper and J. C. Olson 20
Beasley No. 2 mine, by M. R. Klepper and E. Wm. Heinrich 22
Big Flint mine, by E. Wm. Heinrich 26
Big Ridge mine, by M. R. Klepper and E. Wm. Heinrich 28
Bowers mine, by D. M. Larrabee and E. Wm. Heinrich 32
Cox mine, by W. C. Stoll 32
Engle Cope mine, by E. Wm. Heinrich 34
Frady mine, by D. M. Larrabee 36
Iotla-Bradley mine, by D. M. Larrabee 37
Kiser mine, by E. Wm. Heinrich 38
Lyle Knob mine, by J. M. Parker III and W. C. Stoll 40
Moody mine, by J. M. Parker III and W. C. Stoll 42
Poll Miller mine, by E. Wm. Heinrich 42
Rocky Face Knob mines, by W. C. Stoll and J. M. Parker III 46
Sheep Mountain mine, by E. Wm. Heinrich 47
Shepherd Knob mine, by J. C. Olson . 48
Stillwell mine, by J. C. Olson 50
Tilley mine, by E. Wm. Heinrich 53
Turkey Nest and Lyle Cut mines, by M. R. Klepper 54
IV
CONTENTS
—
Continued
ILLUSTRATIONS
Page
FIGURES
Figure 1. Index map showing location of the Franklin-Sylva
district, N. C. L 2
2. Structure Contours on top of pegmatite body, Big Ridge
mine, Haywood County 30
3. Map and sections of the Engle Cope mine, Jackson County- 36
4. . Map of the Iotla-Bradley mine, Macon County 38
5. Map and sections of the Rocky Face mine, Macon County____ 47
6. Map and section of the Tilley mine, Jackson County 54
PLATES
Plate 1. Map showing relation between Franklin-Sylva and
Cashiers districts, N. C. 3
2. Map of the Franklin-Sylva district, N. C, showing loca-tions
of mines and prospects In pocket
3. Map and sections of the Allman Cove mine, Macon County 21
4. Map and sections of the Beasley No. 1 mine, Macon County__ 23
5. Maps and sections of the Beasley No. 2 mine, Macon County.- 25
6. Maps and sections of the Big Flint mine, Jackson County 27
7. Map of the Big Ridge mine, Haywood County 29
8. Sections of the Big Ridge mine, Haywood County 31
9. Map and sections of the Bowers mine, Jackson County :___ 33
10. Map and sections of the Cox mine, Jackson County 35
11. Map and sections of the Kiser mine, Macon County 39
12. Map and sections of the Lyle Knob mine, Macon County 41
13. Map and sections of the Moody Mine, Macon County 43
14. Map of the Poll Miller mine, Macon County 44
15. Underground maps and sections of the Poll Miller mine,
Macon County 45
16. Map and sections of the Sheep Mountain mine, Jackson
County 49
17. Map and sections of the Shepherd Knob mine, Macon
County 51
18. Map and sections of the Stillwell mine, Jackson County 53
19. Map and sections of the Turkey Nest mine, Macon County 55
LETTER OF TRANSMITTAL
Raleigh, North Carolina
March 9, 1946
To His Excellency, Hon. R. Gregg Cherry,
Governor of North Carolina.
Sir:
I have the honor to submit herewith, manuscript for publi-cation
as Bulletin 49, "Mica Deposits of the Franklin-Sylva
District, North Carolina," by J. C. Olson and others.
From 1900 through 1940 North Carolina produced 60 per-cent
of all the mica mined in the United States. The value of
sheet mica produced in North Carolina in 1944 was 480 percent
greater than that produced in 1941.
The Franklin-Sylva district ranks second in total production
among the mica mining areas of the Southeastern states and
supplies approximately 20 percent of North Carolina's output.
It is believed that the information contained in this report will
be of value to the mining industry of the area covered.
Respectfully submitted,
R. Bruce Etheridge,
Director.
VI
PREFACE
This report entitled "Mica Deposits of the Franklin-Sylva
District, North Carolina" has been prepared cooperatively by the
U. S. Geological Survey and the N. C. Department of Conserva-tion
and Development. It represents the work of twelve geologists,
all of whom are properly credited either in the text or on the maps
of the report.
This report is a companion volume to Bulletin 43, "Economic
Geology of the Spruce Pine District, North Carolina." These
two reports, Bulletins 43 and 49, cover the major mica producing
areas of North Carolina. While the Spruce Pine and Franklin-
Sylva districts represent the most important of the State with
respect to the volume and value of mica produced, there are
several others of considerable importance. Most of these have
been studied during the cooperative program and are being de-scribed
in an over-all report being prepared for publication by
the United States Geological Survey.
Jasper L. Stuckey,
State Geologist.
vn
MICA DEPOSITS OF THE FRANKLIN-SYLVA DISTRICT,
NORTH CAROLINA
GENERAL SUMMARY
By J. C. Olson
ABSTRACT
The Franklin-Sylva district ranks second in total mica production among the mining areas of the
Southeastern states. It is underlain almost wholly by metamorphic rocks that include mica, hornblende,
garnet, and kyanite gneisses. The majority of the mica-bearing pegmatites cut across the foliation of the
older rocks and were probably emplaced in fractures. Some of the bodies are more than 100 feet thick,
but most are 5 to 15 feet thick. The plunges of pegmatite bodies are not consistent throughout the district.
Mining is for mica almost exclusively, although feldspar has been the principal product of at least four
mines. The heavy demand for mica during the war years has resulted in increased mining activity and
made the time opportune for detailed study of the deposits. Large-scale maps have been prepared of many
mica mines.
The mica is commonly localized into certain parts of the pegmatite bodies, called "shoots" or "streaks,"
which are mined selectively. The position of the mica shoots varies among the different pegmatites. The
mica blocks may be found clustered near quartz cores that make up a third or a fourth of the total thickness
of some pegmatite bodies, near walls or inclusions, in sporadic "pockets", or disseminated throughout the
pegmatite body. Granite and pegmatite occur together in five composite dikes.
The quality of mica has been an increasingly important factor in all mica mining. Wartime demands
have led to selective mining of the high-quality, flat, clear, easily-split sheet mica in sizes larger than 1
square inch. Much of the Franklin-Sylva mica is clear and of rum (light-brown) or ruby color. Dark rum
(brown) and green mica that is partly stained predominates along the southeast edge of the district and in
the less-productive Cashiers district ten miles to the southeast.
In the average sheet-mica mining operation, from 5 to 15 tons of rock are moved daily, yielding from
a few to 500 pounds of block mica. Total mica in the rock mined probably ranges from 3 to 10 percent at
most good mica mines, but if mine scrap and mica too small to be recovered are excluded, the remaining
block mica probably averages only one to four percent of the rock mined. Feldspar mining has seldom been
profitable in the district, owing to the high cost of transportation to the nearest market at Spruce Pine, but
coarse potash feldspar occurs in some of the pegmatites. «
It is estimated that the Franklin-Sylva district has supplied nearly 20 percent of North Carolina's out-put
of mica during the period 1920 to 1940. About half of this was from the Big Ridge mine. The average
annual output of the district for the years 1920-40 is estimated as nearly 126,000 pounds of sheet and
punch mica. There is no geologic reason why this rate of production should not remain approximately the
same under similar economic conditions. The rate of production attained during the war years 1942-44 is
the best index of the district's potentialities under more intensive development.
INTRODUCTION
The importance of mica to the nation during the war has resulted in great expansion of mica mining in
the Franklin-Sylva district as well as other domestic mica-producing areas. Many old mica mines have been
reopened and new prospects developed. The intensive mining activity has exposed many pegmatites and
made the time opportune for detailed geologic study of the deposits. Detailed mapping of mines and geo-logic
study of the mica occurrences have been very useful both in the evaluation of specific deposits and as
a guide in their development. The geologic work on which this report is based was designed primarily for
immediate use as a guide to mining operations, but the data obtained on the geology and extent of mine
workings should be of practical value in the future as well.
2 Mica Deposits of the Franklin-
To facilitate the production of domestic mica, the Colonial Mica Corporation was established in 1942 as
an agent of Metals Reserve Company. During the period of great demand and unusually high prices, the
Colonial Mica Corporation became the sole purchasing agent for high-quality sheet and punch mica in this
country. The Corporation has aided miners by supplying them equipment at nominal rentals, by advancing
funds to be used in opening promising mines or prospects, and by providing men experienced in the mica
industry to advise operators on the mining and preparation of mica.
GEOGRAPHY
The Franklin-Sylva pegmatite district, in southwestern North Carolina, includes parts of Macon, Jack-son,
Haywood, and Transylvania counties. (See fig. 1.) The southwest boundary of the district is arbi-trarily
taken as the line between Macon and Clay counties, but scattered deposits have been mined in Clay
Fig. 1.
—
Index Map Showing Location of the Franklin-Sylva
District, N. C.
County and northeast Georgia. The Franklin-Sylva district is a northeast trending belt 14 miles wide and
45 miles long, in which hundreds of pegmatites have been mined or prospected for mica. This district
ranks second in total mica output among the mining areas of the Southern Appalachian region ; feldspar,
kaolin, corundum, garnet, dunite, copper, and vermiculite have also been mined.
The Cashiers district, another area in which many mica-bearing pegmatites occur, lies southeast of the
Franklin-Sylva district. In a few places the two districts almost join, as shown in plate 1, but elsewhere
they are separated by a relatively barren area in which very few mica-bearing pegmatites occur. This re-port
deals primarily with the Franklin-Sylva district, but also contains a discussion of its geologic relations
to the less productive Cashiers district. The locations of mines in the Franklin-Sylva district are shown in
plate 2.
The Franklin-Sylva district is in the Appalachian Mountain region, among transverse ridges that lie
between the Blue Ridge on the southeast and the Smoky Mountains on the northwest. Altitudes range from
1,950 feet on the Tuckasegee River to 6,540 feet on Richland Balsam. Much of the district is mountainous,
but basin-like areas one to four miles wide along the principal rivers are characterized by gently rolling
topography. The rocks are commonly weathered, in places to depths of more than 100 feet. Hard out-crops
are most abundant on the steeper slopes. The principal streams, the Pigeon, French Broad, Tuckase-
Sylva District, North Carolina
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4 Mica Deposits of the Franklin-gee,
Little Tennessee, and Nantahala Rivers, are upper tributaries of the Tennessee River, which flows west-ward
into the Ohio River near its junction with the Mississippi.
The district is served by the Murphy Branch of the Southern Railway, which passes through Canton,
Waynesville, and Sylva. The southwest part of the district is also served by the Tallulah Falls Railway,
connecting Franklin with the Southern Railway at Cornelia, Georgia. Federal and State highways and many
county roads make all parts of the district readily accessible.
The Colonial Mica Corporation has maintained an office in Franklin and a mica-trimming and buying
shop in Sylva to serve the Franklin-Sylva district. Other plants utilizing pegmatite minerals at the present
time (October 1944), are four scrap-mica plants near Franklin and many mica-trimming shops for prepa-ration
of sheet mica mined in the district.
FIELD WORK AND ACKNOWLEDGMENTS
This report is based upon field work done by the Geological Survey, U. S. Department of the Interior,
in cooperation with the North Carolina Department of Conservation and Development. The work has been
carried on intermittently since June 15, 1942, and is still continuing (October 1944). The investigations
during 1942 consisted of reconnaissance examination of 254 mica mines and prospects and the detailed map-ping
of two of the largest mines. In 1943 and 1944 detailed geologic maps were made of 64 individual de-posits,
and many others were examined. The mine mapping was done on scales ranging from 20 to 50 feet
to the inch. Control for surface mapping was obtained by plane-table and alidade, whereas underground
surveying was done by compass and tape methods. The following geologists have participated in this work
:
Date
J. C. Olson June 15 to November 30, 1942.
February 19-24 and March 5-10, 1943.
May 23 to August 6, 1944.
J. J. Page June 20 to September 7, 1942.
W. C. Stoll February 8 to June 1, 1943.
J. J. Norton February 8 to 20, 1943.
J. M. Parker, III February 19 to July 4, 1943.
V. C. Fryklund, Jr June 24 to July 4, 1943.
D. M. Larrabee December 6, 1943 to February 10, 1944.
M. R. Klepper December 6, 1943 to May 12, 1944.
W. B. Allen December 13 to 31, 1943.
E. Wm. Heinrich January 4, 1944, to ?
L. C. Pray January 1944 to May 19, 1944.
R. W. Lemke July 27, 1944, to ?
The investigations in 1942 were under the general supervision of G. R. Mansfield; during 1943 and
most of 1944 they were under the general direction of H. M. Bannerman and from the latter part of 1944
to the present they have been directed by E. N. Cameron. R. H. Jahns, who has been in charge of pegmatite
studies in the Southeast since May, 1944, made helpful criticism of the manuscript and illustrations. E. Wm.
Heinrich prepared many of the illustrations as well as mine descriptions. The writer is indebted to Dr. J. L.
Stuckey, State Geologist of North Carolina, for his interest and wholehearted cooperation in the work.
Colonial Mica Corporation, agent for Metals Reserve Company, has given full cooperation as well as
much information of value to the present study. W. E. Grindstaff of the Asheville Mica Company kindly
furnished records of mica sales over a 20-year yeriod. Many miners and other residents of the district have
given information regarding mining history and the location of mines.
PREVIOUS WORK
The geology of much of the Franklin-Sylva district has been described by Keith1
, and many of the mica
deposits have been described by Sterrett2
.
'Keith, Arthur, U. S. Geol. Survey, Geol. Atlas, Pisgah (No. 147) and Nantahala (No. 143) folios. Cowee quadrangle (un-published.)
" Sterrett, D. B., Mica deposits of the United States: U. S. Geol. Survey Bull. 740, 1923.
Sylva District, North Carolina 5
GENERAL GEOLOGY
METAMORPHIC ROCKS
The district is underlain almost wholly by metamorphic rocks, mapped by Keith3 as the Carolina (domi-nantly
micaceous) and Roan (dominantly hornblendic) gneisses. Several varieties of mica gneiss are inter-layered
in various proportions. They range in composition from schist that is rich in muscovite, with a
little quartz, feldspar, and biotite, to the more abundant quartzose mica gneiss in which the mica flakes are
sparsely distributed. Garnet and kyanite are prominent in some of the gneisses. A few fine-grained grani-toid
layers occur among the other rock types.
Feldspathic gneisses are commonly interlayered with the other rocks. In places the schistose rocks
contain much introduced quartz and feldspar, as pods or lenses from a fraction of an inch to several inches
in thickness, especially near larger pegmatite bodies. Much of the gneiss and schist in the vicinity of
granite bodies in the Cashiers district appears to have been permeated by pegmatitic and granitic solutions.
Small pods, lenses, and stringers of pegmatite along the foliation planes of metamorphic rocks are much
more common in the Cashiers district and the southeast part of the Franklin-Sylva district than they are
in the main belt of Franklin-Sylva mica deposits.
Hornblende gneiss and schist occur both as layers from a few inches to 100 feet thick in the micaceous
rocks and as larger units mapped as Roan gneiss by Keith. The hornblende schist consists mostly of black
hornblende needles, about one-tenth to one-half an inch in length, with quartz, feldspar, and a little biotite.
The hornblende gneiss is a banded rock composed of alternating dark (hornblendic) and light (quartz-feld-spar)
layers.
The micaceous schist and gneiss are largely of sedimentary origin. Some of the hornblendic rocks may
be sills, but their interlayering with diverse rock types and the absence of cross-cutting relations suggest
that they probably are largely of volcanic or sedimentary origin.
WEATHERING
The best outcrops are found on the steep slopes, and are composed predominantly of mica-garnet gneiss
and kyanite gneiss. Most of the rock in the topographic basins near the rivers is weathered deeply, yielding
light-red to reddish-brown and brown to brownish-yellow soils. In general the hornblendic rocks yield red
clay soils, although some are yellowish brown. The mica and garnet gneisses yield yellow, brown, and gray
soils. Red soils are more plentiful in the valleys and plateaus, presumably because the weathering is more
advanced and the iron-bearing minerals therefore more oxidized.
IGNEOUS ROCKS
COARSE-GRAINED GRANITE
Coarse-grained granite, in part pegmatitic, underlies areas as much as 18 miles long and 5 miles wide
in the Cashiers district, and extends southwestward into Georgia and South Carolina. (See pi. 1.) This
rock was called the Whiteside granite by Keith4
. It is light colored and is composed of quartz, orthoclase
and plagioclase feldspars, and a little muscovite and biotite. Patches and streaks of coarser pegmatite of
similar composition occur within the granite. The principal granitic intrusions are thick sill-like bodies
that appear to have bulged the overlying metamorphic rocks upward. Many thin sills of granite occur, in
the adjacent mica gneiss, and slab-like inclusions of gneiss are common in the granite. The gneisses have
been permeated with quartz and feldspar over large areas near the granite. The granite resembles that at
Spruce Pine5
, in its texture and structural relation to the metamorphic rocks.
OTHER granitic bodies
Fine- to medium-grained biotite granite occurs in large and small areas several miles northwest of the
Franklin-Sylva mica belt. It is unlike the Whiteside granite, and has been correlated with the Cranberry
3 Keith, Arthur, op. cit.
1 Keith, Arthur, Pisgah folio: U. S. Geol. Survey Geologic Atlas, No. 147, 1907.
6 Hunter, C. E., Residual alaskite kaolin deposits of North Carolina: Amer. Ceramic Soc. Bull., vol. 19, no. 3, pp. 98-103,
March 1940.
Olson, J. C, Economic geology of the Spruce Pine pegmatite district, North Carolina: North Carolina Dept. Cons, and
Devel. Bull. 43, 1944.
6 Mica Deposits of the Franklin-granite
by Keith6
. Its largest area of outcrop is north and west of Canton, but smaller bodies occur in the
Nantahala Mountains and north and west of Franklin.
Granitic dikes are sparsely distributed in the district as a whole, but are most plentiful in the north-east
and central part. Most of them are between three inches and six feet thick, and are composed of fine-grained
feldspar and quartz, fine muscovite and biotite flakes that are commonly parallel to one another,
and scattered small garnets. Porphyritic varieties have medium- to coarse-grained feldspar, quartz, or bio-tite,
in a finer-grained matrix. Fine-grained, slightly foliated granite dikes, eight inches to five feet thick,
are best exposed at the Sally Reed, Bee Tree No. 1, Rock, Diller Bryson, and Island Ford mines. Most of
them cut the pegmatite bodies and are doubtless younger, although the difference in age may not be great.
Aplite dikes are cut by pegmatite at the Iotla-Bowers mine. They are two feet thick on the average, uni-form
in grain size, and composed of an intimate mixture of quartz and kaolinized feldspar.
Granite and pegmatite occur together and are genetically related in the composite dikes at the Tilley,
Roarenhole, Moss, Borrows Cut, and Big Ridge pegmatites. The granite and the pegmatite in these unusual
deposits were formed at essentially the same time. The granite, described on p. 10, is fine- to medium-grained
and is distinctly different from the coarse-grained Whiteside granite.
DUNITE
Small bodies of ultrabasic rocks occur in the district. They are generally elliptical in plan, having a
maximum width of as much as 0.4 mile, and a maximum length of more than 2 miles7
. They are most
extensive in the Webster-Addie-Balsam area of Jackson County. As Hunter points out, the individual
bodies in the Webster-Addie area are arranged along the circumference of a circle, forming a discontinuous
ring-dike. Numerous isolated dunite bodies occur in other parts of the district. Dunite, consisting almost
entirely of olivine, and an impure soapstone containing amphiboles are the most common varieties. The
dark, rocky ground where they occur supports little vegetation. These rocks were observed by Keith8 to cut
across the Roan gneiss.
STRUCTURE
FOLDS
The planes of schistosity have been folded on a large and small scale. The schistosity strikes rather
uniformly northeast over much of the district, but local deflections to a northwest strike are not uncommon.
Almost all the foliation in the Franklin-Sylva district dips at an angle greater than 45 degrees and much is
approximately vertical. In the Cashiers district the dips are less steep on the average, many of them less
than 45 degrees. The decrease of dip southeastward is similar to that in the Spruce Pine district 100 miles
northeast.
FRACTURES
Fracturing of the metamorphic rocks has an important bearing on the distribution of commercial mica
because fractures formed prior to pegmatite introduction guided the incoming solutions and, in pegmatite
already solidified, rock movements crush or "rule" the mica. Faults and joints are numerous in the Franklin-
Sylva district, but the faults observed are probably not of very great displacement. Some of the fractures
have been filled with quartz or pegmatite.
The general character of the fracturing may be seen in a road cut about 200 feet long on Savannah
Creek. There the strike of the foliation of the gneiss is nearly uniform in the cut, but the dip changes
abruptly within short distances because of close folding. Four parallel pegmatite bodies one to two feet
thick cut the gneiss. They dip steeply, have sharp walls, and presumably fill fractures. A gently-dipping
normal fault, along which drag is evident, cuts the gneiss. This fault has been filled with quartz, but other
small faults exposed have no filling. In general this example is thought to typify the structure of the
district. Steeply-dipping, parallel pegmatite bodies, emplaced in fractures, cut the country rocks. Later
• Keith, Arthur, op. cit.
7 Hunter, C. E., Forsterite olivine deposits of North Carolina and Georgia: North Carolina Dept. Cons, and Devel. Bull. 41,
1941.
9 Keith, Arthur, op. cit., p. 3.
Sylva District, North Carolina 7
faults cut wall rocks and pegmatite. These post-pegmatite faults are numerous in the Savannah section of
Jackson County, but they occur throughout the district. They have effected much ruling and bending of the
mica books.
Many contact relations indicate that pre-pegmatite faults were channels for incoming solutions. Sharp
changes in strike of foliation a few inches to three feet from the pegmatite body may be the result of drag
along a fault prior to the introduction of pegmatite. Evidence of such drag was observed at the R. T.
Bryson, Poll Miller, Winecoff, Dills, Lin Cove, Wilkes, and other mines. At the Jack Knob mine, for example,
the foliation of the biotite gneiss at the contact is very nearly parallel with the walls of the pegmatite body,
but it changes two feet from the contact from a northwest strike to nearly due east, through an angle greater
than 90 degrees.
Fractures in the metamorphic rocks undoubtedly controlled the disposition of many of the pegmatites.
This control is indicated by the parallelism of tabular discordant pegmatite bodies, for example those in the
Panther Knob area of Jackson County and those in a belt extending three miles northwest from the town of
Franklin. Abrupt bends in cross-cutting pegmatite bodies, and offshoots or apophyses having diverse atti-tudes,
provide additional evidence of the existence of a pre-pegmatite fracture pattern.
Contacts between pegmatite and wall rock are comparatively sharp in the nearly tabular pegmatite
bodies that appear to have formed in fractures. Not all the pegmatite bodies are tabular or so sharply
defined, however, for some have very irregular walls. Notable examples of irregular-walled pegmatite
bodies are the Burr Knob, Iotla-Bradley, Gurney Clay, Shepherd Knob, and Dillard mines.
The effect of pre-pegmatite fracturing of the rocks is more pronounced in the Franklin-Sylva district
than it is to the southeast in the Cashiers district. The invasion of the granitic magma near Cashiers was
accompanied by profound "soaking" of the metamorphic rocks, and schistosity was most important as a
guide to incoming pegmatitic and granitic solutions.
PEGMATITES
SIZE AND SHAPE
The pegmatite bodies range from lenses a fraction of an inch thick to great masses such as the Big
Flint, Iotla-Bradley, Shepherd Knob (each 100 feet or more thick), Lin McCall (50 feet), Roda (about 150
feet), Gradin (65 feet), and Gurney Clay (50-200 feet). Thicknesses vary, but some pegmatite dikes that
appear to have formed in fractures are nearly uniform in thickness for 100 feet or more along the strike.
Many pegmatite bodies are lenticular, and thin rapidly along the strike. For example, the thickness of the
"Little Vein" at the Welch mine diminishes from 4 feet to 5 inches within a strike distance of 20 feet. The
quartz core and associated mica are present where the pegmatite body is 4 feet thick, but not where it is
only 5 inches thick.
The pegmatite bodies have a variety of shapes. Some are tabular or sheet-like (Frady) ; some are
elongate lenses (Iotla-Bowers) ; some are very irregular (Shepherd Knob, Dillard). Some vein-like quart-zose
bodies are thin and have irregular gradational contacts (Rock, Cedarcliff, and Bee Tree No. 1) ; others
are merely small lenses, some without visible connection, disposed along a plane or in imbricate arrangement
in the gneiss or schist. At the Island Ford mine, for example, lenses one to three feet thick were mined
along a thin, conformable layer of gneiss that contained many pods and stringers of pegmatite material.
Books of mica have been found here in the wall rocks of gneiss.
STRUCTURE
Most of the pegmatite bodies dip steeply, and the majority cut across the foliation of their wall rocks.
Some strike parallel to the foliation, but transect it in dip ; this type is particularly common in an area of
several square miles northwest of Franklin. "Rolls", or abrupt changes in dip, are common.
The pegmatite and associated granite body at the Big Ridge mine (see description, pp. 28-32) are arch-shaped,
as is the pegmatite body at the Cox mine (pp. 32-34) . A somewhat similar bend occurs in the Shep-herd
Knob pegmatite (described on pp. 48-50). In all these deposits, at least one of the limbs of the arch
crosscuts the wall-rock foliation. The arched shape is apparently due to the arrangement of intersecting
8 Mica Deposits of the Franklin-fractures
that guided the solutions, and not to subsequent folding of both pegmatite and wall rock or to the
introduction of solutions conformably along the crest of an anticlinal fold in the gneiss.
The plunges of pegmatite bodies are not consistent throughout the district. Many of the tabular bodies
have been mined directly down the dip, whereas in the Spruce Pine district to the northeast the predominant
plunge of pegmatite bodies is toward the south or southwest at angles of 20 to 40 degrees. Plunges other
than directly down dip have been established for at least a dozen Franklin-Sylva pegmatite bodies, or parts
of the bodies, including the following: Baird (one of several pegmatites on property), plunges 30° SE. to
horizontal; Beasley No. 2, 35° SE.; Bowers, 45° NW.; Buoy No. 1, 20° NW. to 60° NW.; Buoy No. 2, 25°
NW.; Cox, 10° S68°W.; Lyle Knob, 25° W.; May, 25° N45°W.; Moody, 60° S55°W.; Poll Miller, 24° NE. to
40°NE.; Raby, 47° S82°E.; Shepherd Knob, 15°N. to 20°N. The diversity of direction suggests that such
plunging structures are related to local rather than regional structural elements.
WALL-ROCK ALTERATION
The metamorphic wall rocks or inclusions may be altered by pegmatitic solutions both through the
coarsening of mineral grains in the gneiss or schist, and through the addition of pegmatite minerals. Small
lenses of quartz or feldspar are common in wall rocks, especially in the more schistose varieties. Pyrite
and pyrrhotite occur in wall rocks, particularly adjacent to certain quartzose pegmatites. Examples of the
coarsening of wall-rock minerals are numerous. At the Shepherd Knob mine, for example, the rocks near
the pegmatite are markedly different from the more normal country rock exposed in adits 200 to 300 feet
away. There are several types of wall-rock alteration at the Shepherd Knob: (1) mica books as much as
1.5 inches in diameter are present in the wall rocks and inclusions, generally with their cleavages perpen-dicular
to the foliation and enclosing many small garnets; (2) the wall rock has been permeated with peg-matitic
feldspar and quartz; and (3) the mica gneiss has become enriched in mica and thereby changed to
mica schist. The first two types of alteration yield a rock that is gradational between true pegmatite and
wall rock.
MINERALOGY
The pegmatities of the Franklin-Sylva and Cashiers districts contain microcline and plagioclase feld-spars,
quartz, muscovite, biotite, garnet, allanite, apatite, magnetite, tourmaline, ankerite, beryl, samarskite,
hedenbergite, and such sulfide minerals as pyrrhotite, pyrite, and, chalcopyrite.
Most of the quartz in the Franklin-Sylva district is white or sugary. A little is gray or smoky, but
gray quartz is more abundant in the Cashiers pegmatite belt to the southeast. Veins of white quartz contain-ing
a little ilmenite and iron oxide are common in all the country rocks. They range from a fraction of an
inch to about four feet in thickness.
Potash feldspar (microcline) is the dominant feldspar in many of the pegmatites, but plagioclase pre-dominates
in most mica-bearing streaks. It is often difficult to distinguish feldspars because they are almost
completely altered to kaolin in the surficial portions of many pegmatites. Graphic intergrowths of quartz
and feldspar (graphic granite) are rare.
Biotite is an abundant pegmatite mineral, and much of it is intergrown with muscovite. In some peg-matites
it occurs as long strips—as much as five feet long at the Putman mine. Biotite probably constitutes
at least a third of the mica at the Big Ridge mine, and at the J. Radeker mine it appears to be l 1/^ to 2 times
as abundant as muscovite. It is exceptionally plentiful at the Ray Cove mine, in blocks as large as 6 x 8 x %
inches. Perhaps its abundance here is due partly to interaction between the pegmatite and hornblende-garnet
gneiss, which forms the wall rock at this mine but at very few others. The pegmatite at the Sheep
Mountain mine, whose wall rock is quartz-biotite gneiss, is exceptional in having a large proportion of both
biotite and muscovite. (See description, pp. 47-48.) Some of the biotite strips occur near the margins of.
massive quartz bodies—for example in the Moody mine (p. 42) and the Big Flint (pp. 26-28).
Garnet is sparsely distributed in the pegmatites, but it occurs in 2-inch crystals at the Blanton prospect.
Apatite and allanite occur in a few pegmatites. Black tourmaline is found at the Painter mine, and at the
Slagle mine at Rainbow Springs. Black and pink tourmaline, samarskite, and beryl have been reported by
J. H. Pratt9 from the Grimshawe mine in the Cashiers district. There is little or no beryl in the Franklin-
Sylva district, but some gem material has been mined in the Cashiers district.
' Sterrett, D. B., op. cit., p. 216.
Sylva District, North Carolina 9
Sulfide minerals are widely distributed, and commonly occur in quartzose pegmatites or in massive
quartz bodies in larger feldspathic pegmatites. Pyrrhotite and pyrite are plentiful in the quartzose peg-matites
at the Bee Tree No. 1, Rock, Cedarcliff, and Shiny mines. Chalcopyrite and bornite occur with the
more common pyrrhotite and pyrite at the "C" mine, and masses of pyrrhotite with chalcopyrite, weighing
as much as a half-pound, occur at the Thorn Mountain mine. Veinlets of sulfide minerals at the Tilley mine
cut all the other minerals. The sulfide minerals appear to be among the last to form in the sequence of peg-matite
minerals.
MINERAL DISTRIBUTION
The economic value of a pegmatite body depends to a great extent upon the degree to which the minerals,
particularly mica, are localized or concentrated into "shoots" or "streaks". Pegmatites in the Franklin-
Sylva district in which the minerals are distributed more or less uniformly seldom can be mined profitably
for sheet mica. Mineral proportions vary along the strike or down the dip of a pegmatite body. The mining
is usually done in parts of the pegmatite bodies where the valuable minerals are most conspicuously localized.
QUARTZ CORES
Massive quartz forms the central part, or core, of many pegmatite bodies, commonly comprising a fourth
to a half of the total thickness of a dike. The quartz mass at the Big Flint mine is as much as 65 feet thick
(see pi. 6) ; that at the Shepherd Knob mine is at least 20 feet thick (pi. 17). The quartz bodies have the
form of irregular lenses, somewhat elongate in the direction of plunge of the pegmatite body. In shape they
range from attenuated, almost tabular lenses (Poll Miller mine, pis. 14 and 15; Turkey Nest and Lyle Cut
mines, pi. 19) to lenses with thickness nearly equal to strike length (Big Flint mine, pi. 6; Roda mine).
Many are discontinuous and are distributed unevenly along the strike or plunge of the pegmatite body.
The thickest part of many of the quartz cores coincides with the thickest part of the enclosing peg-matite
bodies and, in places, with abrupt bends in strike or dip of the pegmatites. The thick quartz mass at
the Moody mine (pi. 13), for example, occurs in a segment of the pegmatite that trends N.60°E., whereas
both east and west of this segment the strike is slightly north of west and the pegmatite is not so conspicu-ously
zoned. Likewise the parts of the Moody pegmatite richest in mica, where the quartz is thickest, may
coincide with a slight decrease in the dip of the pegmatite body. A quartz core in the thickest part of Iotla-
Bowers pegmatite coincides with an abrupt change in strike of the footwall from N.60°W. to N.8°W. In
general this dike dips steeply southwest and is practically homogeneous except for small scattered quartz
pods and a slightly higher mica content along the footwall than in other parts. The deposit has been mined
most intensively in a segment with a strike length of about 50 feet, in which the quartz core occurs.
The typical quartz core is thickest near the central part of its strike length. In places (Raby, Welch
mines) the quartz cores end very bluntly in plunging noses. In other pegmatites the quartz cores thin
gradually until so small that they become indistinguishable among the other grains in the pegmatite. Beyond
its vanishing point the quartz core may be succeeded by or grade into another central zone that differs from
the wall zones; for example, the quartz mass in the middle of the Beasley No. 2 pegmatite (pi. 5) disappears
along the strike and is supplanted by a plagioclase-mica pegmatite that differs from the wall zones in contain-ing
much muscovite and biotite. At the Stillwell mine (pi. 18) the quartz core exposed at the base of the
123-foot New shaft grades southward into quartz-muscovite pegmatite ("burr rock"), and northward into
quartz-feldspar pegmatite. At the Poll Miller mine (pis. 14 and 15, description on p. 46) the quartz core is
supplanted to the southwest by a thick central rib of coarse blocky microcline, which in turn grades into
medium-grained feldspar-quartz pegmatite. Block muscovite is abundant in the wall zones at the Poll Miller
both where the central part of the dike is quartz and where it is coarse microcline.
"BURR ROCK"
Pegmatitic quartz containing many small (Vi to 1 inch), sub-parallel mica flakes is known locally as
"burr rock". At the Shepherd Knob mine the "burr rock" appears to be a marginal phase of the large quartz
core. At the Allman Cove mine (pi. 3), however, "burr rock" is more common than massive quartz, which is
confined to small masses two or three feet thick near the west end of the mine. The bodies of "burr rock"
range from an inch to a foot or more in thickness and are discontinuous. "Burr" streaks lie parallel to and
within a few feet of each wall of the Allman Cove pegmatite, and another, near the middle, also follows the
10 Mica Deposits of the Franklin-east
trend of this pegmatite ; others have a northeasterly trend. Sheet mica occurs either in the "burr rock"
or in the adjacent plagioclase. Much of the mica produced from the Miller mine was derived from "burr
rock".
BORDER ZONES
Fine-grained border zones generally less than a foot thick are present along the walls of many pegmatite
bodies. The border zones are mostly plagioclase and quartz, but also contain mica flakes y± to 1 inch in di-ameter
and small garnets in some places. The cleavage planes of the mica flakes tend to be perpendicular to
the contacts. The grain size increases inward from the walls.
FELDSPATHIC PEGMATITE
The parts of the pegmatite bodies other than the border zones and the massive quartz cores will be con-sidered
herein as "feldspathic pegmatite", inasmuch as feldspar is the predominant mineral except in rare
varieties of quartzose pegmatite. Various kinds of feldspathic pegmatite may be distinguished according to
the proportions of microcline, plagioclase, quartz, and other minerals. Numerous examples of feldspathic
pegmatite are shown on the mine maps accompanying this report. It is possible in most pegmatite bodies to
distinguish more than one type of feldspathic pegmatite, although this distinction is difficult when the feld-spars
are weathered. A common distinction is that made between plagioclase-quartz pegmatite and micro-cline-
quartz pegmatite. The microcline-rich parts of the pegmatite bodies are generally in the interiors,
whereas the plagioclase-rich parts tend to occur along the margins. Commercial muscovite is most abundant
in the plagioclase-quartz type.
GRANITE IN PEGMATITE
Granite that forms a component part of the composite dikes at the Tilley, Moss, Borrows Cut, Roaren-hole,
and Big Ridge mines differs from the large granite bodies and granitic dikes described on previous pages.
The granite at each of these five mines is a uniformly fine-grained mixture of oligoclase, quartz, and biotite.
Although the rock contains very little potash feldspar, it will be referred to in this report by the miners'
term "granite".
The composite dike exposed at the Moss (Adams) mine consists of a central granite body three feet
thick, along each margin of which occurs a six-inch to two-foot thickness of fine-grained pegmatite. This
dike is exposed discontinuously from the south end of the mine, where it is V/2 feet thick, to a point a third
of a mile to the north on the Tuckasegee River. Most of the mining was done, however, within a strike dis-tance
of 800 feet ; Sterrett10 has described the pegmatite in the main workings. The pegmatitic zones consist
in some places almost entirely of muscovite, in others of feldspar and some quartz. The contact between the
pegmatite and the granite, according to Sterrett, is irregular and not sharply defined. Many of the mica
crystals, especially near the walls, have cleavage planes normal to the contacts.
The granite and pegmatite at the Big Ridge mine are described on pp. 28-30. Here the mineralogic rela-tions
indicate that much of the pegmatite crystallized later than much of the granite, although the difference
in age is not great. In some places the granite was probably the earliest material intruded along the irregular
fractures, as it forms part of the wall rock of the pegmatite ; in one place, at least, the granite was the last to
form, for a dike 8 inches thick cuts sharply across both pegmatite and earlier granite.
At the Borrows Cut, a dike 5 feet thick has a core 21/2 feet thick of quartzose fine-grained granite in
which biotite flakes and streaks have parallel orientation. The pegmatitic border zones of this composite
body are crowded with small mica books as much as 5 inches in diameter. The granite and pegmatite at the
Tilley mine are described on p. 54.
OCCURRENCES OF MUSCOVITE
Muscovite occurs sporadically in most pegmatites, but where mineable, the blocks are large and clustered
into certain rich "streaks" or "shoots". Table I summarizes the prevailing modes of occurence of mica in the 170
mines in the Franklin-Sylva district in which the localization of the mica could be either observed or inferred.
10 Sterrett, D. B., op. cit., p. 202.
Sylva District, North Carolina 11
They include for the most part the best-exposed pegmatites and those that have the most clearly defined mica
concentrations. Many other pegmatites are difficult to classify because of absence of mica or of pegmatite
exposures. Difficulties arise in such a classification either because of the presence of more than one type of
mica concentration in a single deposit, because the mica is not definitely concentrated, or because incomplete
exposures in many places do not give a full picture of the pegmatite body. Observations are sufficiently
numerous, however, to make the table of value in demonstrating the proportions of the various mica oc-currences.
DISSEMINATED MICA
Mica blocks or clusters of blocks disseminated through a pegmatite body rather than in a well-defined
streak or zone are not likely to be mined profitably for sheet mica. Some weathered bodies of this type, how-ever,
have been important sources of scrap mica. Scrap mica is abundant in the felpspathic pegmatite at the
Iotla-Bradley mine (fig. 4), averaging about 10 percent of the rock and forming as much as 50 percent in
places near quartz bodies. A little mica occurs in the quartz. This and similar pegmatites are classed with
the disseminated deposits because of the presence of mica in such a large part of the pegmatite body, even
though numerous scattered concentrations occur locally.
Scattered clusters of mica blocks occur sporadically in some small, irregular pegmatite bodies. Most
mica at the Bettys Creek mine, for example, is found in thicker parts (as much as 6 feet thick) of the bodies,
and bears no apparent relation to the small quartz bodies or to the walls. Other mica pegmatites in which
the mica is disseminated or sporadic are the Putman, Gibson, Burr Knob, Oscar Queen, and Gurney Clay
mines.
table i
Summary of Mica Localization in Pegmatites of the Franklin-Sylva District
Number of Approximate
Type of mica occurrence examples percent
Disseminated and sporadic distribution 9 5
Quartz core present:
Mica near quartz core 68 40
Mica near walls 24 14
Mica near both quartz core and walls 29 17
Quartz core absent or inconspicuous:
Mica near one wall 15 9
Mica near both walls 15 9
Mica near inclusions and walls 5 3
Mica possibly related to granite bodies within
or in contact with pegmatite 5 3
Total 170 100
MICA RELATED TO QUARTZ CORES
The relation of mica shoots to quartz masses makes the margins of quartz bodies favorable for prospect-ing.
As a general rule, rich mica shoots related to quartz cores tend to occur alongside the thickest parts of
quartz masses. A thick quartz core, however, does not necessarily indicate a concentration of mica, for
quartz bodies are much more numerous than rich mica streaks.
The disposition of the mica blocks with respect to the quartz bodies varies among the different deposits.
In some the mica occurs throughout a thin zone between quartz and wall, but generally it is localized near
either quartz or walls. In the majority of the quartz-core pegmatites, the mica blocks are clustered near the
quartz. At the Raby mine, some mica crystals cross the contact between quartz and adjacent feldspathic
pegmatite. Crystal faces are developed on the parts of the books projecting into the quartz, whereas the
margins of the same books in feldspathic pegmatite (now kaolin) are ragged and irregular.
The mica blocks may be found more or less continuously along the margins of the quartz, but more com-monly
they are clustered in "shoots" or "pockets" separated by leaner feldspathic material. The long dimen-sions
of some "shoots" can be correlated with the plunge of structural features such as flexures ("rolls") in
the walls of the pegmatite body, which generally parallel the plunge of the pegmatite body as a whole. Mines
12 Mica Deposits of the Franklin-at
which the mica blocks adhere closely to quartz cores are the Beasley No. 1, Lyle Cut, "A", Iotla-Bowers,
Raby, Moody, Shepherd Knob, and Locust Tree. The size of the mica blocks generally diminishes away from
the quartz mass.
Different from the above-described pegmatites are those in which the coarser mica blocks lie near the
walls rather than near the central quartz body. Feldspathic zones with very little mica border the central
quartz mass, and are composed of either coarse plagioclase or plagioclase with blocky microcline. Angular
feldspar grains project into the massive quartz. At the Beasley No. 2 mine the coarsest mica blocks are
separated from the hanging wall of the dike by a 6- to 12-inch border zone of medium-grained plagioclase,
quartz, and mica- (see discussion, p. 24) ; coarse oligoclase adjoins the massive quartz. Other examples of
quartz-core pegmatites having mica near the walls are the May, Buoy No. 2, Painter, Bowers, Deets, Locust
Ridge, and Gregory. The cleavage of the muscovite in some of these pegmatites shows a striking tendency
to lie perpendicular to the walls, for example the Frady (p. 37) and Stillwell (p. 52) mines.
The occurrence of muscovite-rich zones along both quartz and walls is not uncommon. Examples are
the Roda, W. G. Dillard, Doc Nichols, and Chalk Hill mines. At the Lin McCall mine, stained green wedge
mica occurs near quartz masses, whereas clear and stained dark-rum mica occurs near the footwall. Mus-covite
has been mined near the quartz core in one pegmatite at the Baird mine; in another on the same
property it occurs near the walls.
Muscovite generally occurs in plagioclase-rich pegmatite, in the Franklin-Sylva district as in other mica-producing
pegmatite districts. 11 At the Farlow Gap mine, for example, coarse muscovite occurs near the walls
in plagioclase pegmatite rather than in the quartz-microcline core. The central part of the Lyle Knob peg-matite
body (pi. 12) is massive quartz, in places containing abundant microcline. Mica is concentrated near
the walls of the pegmatite body where the percentage of plagioclase in the rock is higher.
Inasmuch as microcline tends to occur in the central parts of the zoned pegmatites of the Franklin-Sylva
district rather than the margins, muscovite in a microcline-rich pegmatite would be most likely to occur nearer
the walls. If microcline is scarce or absent, of course, mica may be found in plagioclase-rich zones near
either walls or massive quartz cores.
Differences in mica content on the two sides of a quartz core are common. Mica at the Judge Ferguson
mine was obtained mostly on the south side of a quartz mass four feet thick in a vertical pegmatite body 12
feet thick. Where the distribution is uneven, mica is generally more abundant on the upper side of the
quartz. Differences in quality and color on the two sides of the quartz apparently exist also. For example,
in the Long Branch and Gregory mines ruby mica occurs on the upper, whereas greenish-white specked
mica occurs on the lower, side of the quartz bodies; in the Spence ruby mica on the upper side, and biotite
near the footwall ; in the Double Gap clear, rum mica on the upper side, and stained greenish-rum on the lower
;
and, in the Ramsey Buchanan clear mica on the upper side, and slightly stained on the lower. Two types of
mica occur at a number of other mines in the Savannah section of Jackson County, including the Wilkes,
Kolb, and Collins, but the positions of the two types within these pegmatites is not known. In all the above
occurrences of two colors of muscovite, which are in the Savannah-Greens Creek-Cullowhee area of Jackson
County, the poorer grade of mica is near the footwall.
MICA RELATED TO WALLS
Concentrations of mica are found in close proximity to walls and to inclusions of wall rocks at many
mines. Zones near the walls commonly contain a higher proportion of plagioclase feldspar than the interior
parts of the pegmatites. Where mica blocks occur in quantity along one wall but not the other, the hanging
wall is generally favored. Mica streaks that occur both near walls and inclusions are found in the Caney
Fork area of Jackson County. These pegmatites commonly contain tabular inclusions oriented parallel with
the walls, and the pegmatite bodies, although irregular, generally conform to the foliation of their wall rocks.
Examples of mines at which mica is localized near walls or inclusions are the Engle Cope (fig. 3), Lyle Knob
(pi. 12), Shirley Wilson, Mack, Jeanie Deets, Aaron Hooper, Bud Williams, and Buzzard Roost.
u See, for example:
Olson, J. C, Mica-bearing pegmatites of New Hampshire: U. S. Geol. Survey Bull. 931-P, 1941, p. 375.
Kesler, T. L., and Olson, J. C, Muscovite in the Spruce Pine district, N. C: U. S. Geol. Survey Bull. 936-A, 1942, p. 10.
Cameron, E. N., Larrabee, D. M., et al., Structural and economic characteristics of New England mica deposits: U. S.
Geol. Survey press bulletin, September 1944.
Sylva District, North Carolina IS
MICA ASSOCIATED WITH GRANITE BODIES
Granite bodies, discussed on page 10, are closely related to the mica-bearing pegmatites in at least
five composite dikes. The granite bodies at the Big Ridge and Tilley mines are described on pages 28 and 54.
The granite "cores" at the Moss, Borrows Cut, and Roarenhole mines occupy central positions within peg-matite
masses, like the quartz cores of other pegmatites. Mica occurs in thin layers of coarse-grained peg-matite
along the margins of the granite. It is uncertain at present whether the concentration of the mus-covite
in the coarse-grained pegmatite was due to some effect of the granite, or whether the close spatial
relation betwen muscovite and granite is only coincidental.
SOURCE AND EMPLACEMENT OF PEGMATITE
The source of the pegmatite may best be considered by drawing a comparison with the Spruce Pine
pegmatite district 100 miles to the northeast. The Franklin-Sylva district corresponds to the northwest
half of the Spruce Pine district, inasmuch as it contains very little granite and the muscovite is dominantly
rum or ruby in color and generally clear. The Cashiers district corresponds to the southeast half of the
Spruce Pine district, which is characterized by much granite as well as muscovite that is characteristically
green or brown and not uncommonly stained. The change in color of muscovite in different parts of the dis-tricts
is very broad and general, and local exceptions are numerous.
The granitic bodies in the Spruce Pine and Cashiers districts are coarse and pegmatitic, and are sur-rounded
by shells of gneiss thoroughly permeated by granitic material. The granite of the Cashiers district
probably contains more biotite and potash feldspar on the average than that at Spruce Pine. The main
Franklin-Sylva pegmatite belt is separated from the granite masses of the Cashiers district by a relatively
barren zone 5 to 10 miles wide in which there are very few mica-bearing pegmatites. (See pi. 1.) Similar,
although much smaller, barren areas occur near the middle of the Spruce Pine district. The pegmatites at
Spruce Pine are believed to have been derived from granitic rock whose present exposures lie mostly in the
southeast part of the pegmatite district. 12 Similarly, the probable source of the Franklin-Sylva pegmatites
is a granitic rock at depth, related to or part of the Whiteside granite masses of late Paleozoic age now ex-posed
to the southeast in the Cashiers district (pi. 1). Apparently at the time of this granitic intrusion the
pegmatites were emplaced in fractures and zones of weakness in the already folded and metamorphosed gneiss
and schist.
The minerals in the pegmatites that have formed in fractures appear to have been deposited essentially
from the walls inward. This mode of formation is indicated by the fine-grained border zones, the cores of
massive quartz that in many places have angular contacts with adjacent feldspar crystals, and the variation
in content of microcline, plagioclase, and muscovite with relation to the walls, as described in preceding para-graphs.
Most of the pegmatites are composed of relatively few minerals. Modification of the original peg-matite
by later processes, such as albitization or large-scale replacement, is inconspicuous.
The cores of the composite dikes, described on p. 10, are granite rather than quartz or another type
of pegmatite. The granite at the Big Ridge mine occurs as the core, as part of the wall rock, and as dikes
cutting both pegmatite and wall rock. The crystallization periods of granite and pegmatite here overlapped.
The granite cores of the other composite dikes, like the quartz cores, probably solidified after the pegmatite
along the walls, although the difference in age is probably slight.
MUSCOVITE
PROPERTIES
Muscovite is indispensable as an insulating material in certain types of electrical and radio equipment
because of its unique combination of physical properties and our inability thus far to find a satisfactory
substitute for certain uses. The most important physical properties in determining the value of sheet mica
are cleavage, flexibility, staining, color, intergrowths with other minerals, and certain electrical properties.
To be suitable for the most exacting uses, the mica must split readily into flat, clear, firm, flexible sheets,
without staining, air or water bubbles, pinholes, or other inperfections.
13 Olson, J. C, Economic geology of the Spruce Pine pegmatite district, North Carolina: North Carolina Dept. Cons, and
Devel. Bull. 43, 1944.
14 Mica Deposits op the Franklin-
Muscovite crystallizes in the monoclinic system, and perfect crystals have nearly hexagonal outlines.
Well-formed crystals are particularly common at the Tilley mine and occur sparsely in other pegmatites in
the district, but by far the greater part of the commercial mica occurs as rough blocky masses of irregular
shape. The largest mica block, or "book", reported from the Franklin-Sylva district was found in 1907 at
the Iotla-Bradley (Iotla Bridge) mine. It weighed more than 4,000 pounds, and measured 4 feet in length
or thickness13 and 29 by 36 inches in cross-section.
Certain physical peculiarities of "book" muscovite are of great economic importance. "A" mica is less
valuable than flat, for the surfaces of the sheets are marred by chevron-like "reeves" or lines that intersect at
an angle near 60 degrees, forming a "V". Some of the "A" structures are due to the tapering out of certain
sheets along straight lines ; others are due to closely-spaced folds or corrugations, called "ridges" or "reeves",
and mica possessing this feature is said to be "reeved". "A" mica occurs in variable proportions in most of
the mines in the district, but is of minor quantitative importance at most mines. "A" mica from which flat
mica can be obtained by trimming between the reeves is known as "flat A" mica. Mica crystals, mostly of
"A" type, that taper in thickness are known as "wedge" mica. "Herringbone" mica differs from "A" mica
in having two sets of reeves that intersect a central spine-like set at angles of about 60 degrees. Mica that
tears when split, generally because of the intergrowth of adjacent sheets, is said to be "tanglesheet", "tied",
"gummy", or "locked". Random fine cracks are known as "haircracks". "Ruled" mica is mica that is broken
along sharply defined parting planes that intersect at angles near 60° and lie at an angle of nearly 67° with
the cleavage plane. Ruling that is strongly developed in only one direction yields strips of "ribbon" mica.
Ruling in two or three directions yields sheets of rhombic or triangular shape. Ruled mica results from
distortion of the crystal by rock movements and is conspicuous near faults. The most productive sheet mica
mines are therefore in pegmatites that have not been deformed.
Intergrowths with other minerals impair the mica. The most common is that of muscovite with biotite,
an intergrowth in which the cleavages of the two minerals are parallel. Although the presence of inter-grown
biotite lowers the value of an individual muscovite book, the presence of biotite in a muscovite-bear-ing
rock generally indicates that the muscovite is ruby or rum in color rather than green or stained. Other
minerals intergrown with muscovite are quartz, plagioclase, flat and euhedral garnet, tourmaline, apatite, and
allanite.
The color of muscovite is denoted by the terms ruby (red or pink), rum (light-brown), green, white, and'
dark-rum or brown. Staining of primary origin in mica is due to inclusions of hematite, magnetite, or tiny
flakes of biotite. The type of staining due to small biotite flakes is rare but occurs in the Caney Fork area of
Jackson County. The most common secondary stains are caused by the infiltration of fine clay particles be-tween
the laminae and are called clay stains. Limonite commonly occurs as a result of the alteration of
magnetite and hematite inclusions. Air and water bubbles occur between some sheets. If few, they can be
removed by careful splitting, but if abundant they lower the value of the mica.
The most important electrical property of mica is the power factor. Power factor, expressed in per-cent,
is a measure of the loss of electrical energy in a condenser in which the mica forms the dielectric
medium. Mica having a power factor greater than 0.04 percent is seldom used in condensers. The power
factor of muscovite is greatly increased by the presence of such imperfections as staining, haircracks, pin-holes,
and air bubbles.
CLASSIFICATION AND GRADING
As the mica is taken from the mine, all that is obviously scrap because of physical defects or small size
is segregated as "mine scrap" mica. The remaining mine-run mica is then split and trimmed ("rifted")
in the mica shop. The products of the rifting process are sheet, punch or circle, and shop scrap. The common
sizes into which sheet and punch mica are graded, and the approximate percentages of each size that have
been produced from 12 outstanding mines during the period 1922-42, are shown in table III (page 18)
which includes only mica classed as clear. Punch mica ordinarily includes clear sheet mica smaller than 1*4
by 2 inches but larger than a circle 1*4 inches in diameter, and stained sheet mica smaller than 2 by 2 but
larger than a circle l 1/^ inches in diameter. The circle classification, as employed in the Franklin-Sylva dis-trict,
ordinarily includes sheets ranging from a circle 2 inches in diameter to a 2 by 3 inch rectangle. During
Sterrett, D. B., op. cit., p. 235.
Sylva District, North Carolina 15
the war, in accordance with increased demands for small mica, the minimum acceptable size for punch mica
was lowered to 1 by 1 inch, and prices were based upon full and three-quarter trim, a higher standard of
preparation than existed in pre-war years.
Sheet mica is classified qualitatively into two primary divisions : "clear" and "stained". It may also
be classified as No. 1, No. 2, or No. 3. No. 1 is clear mica of good quality, corresponding approximately to
the Indian and A. S. T. M. grades of "clear", "clear and slightly stained", "fair-stained", and some "good-stained".
No. 2 is less perfect because of curved cleavage, clay-staining, minor iron-oxide staining, or air
bubbles; it corresponds to the Indian "stained" classification and possibly to some Indian "black-stained".
No. 3 mica is heavily stained, like the Indian "black-stained or spotted" mica. The No. 2 mica has been
further divided into "No. 2 regular" and "No. 2 inferior". In general the sizes and qualities in greatest
demand during the war, and for which a premium price has been paid by the Colonial Mica Corporation, in-clude
full-trimmed punch mica larger than 1 by 1 inch and full and three-quarter trimmed sheet mica IV2 by
2 inches or larger, of No. 1 and No. 2 qualities. Prices, classification, and methods of preparation have varied
during the war as well as in pre-war years, and the reader is referred to other publications14 for further dis-cussions
of the mica industry.
QUALITATIVE DISTRIBUTION OF MUSCOVITE
The muscovite throughout the Franklin-Sylva district has a strikingly uniform rum to ruby color. On
the average, mica from the northwest half of the belt has a slightly redder hue than that from the southeast.
Mica from the parallel Cashiers district, 10 to 15 miles to the southeast, has a predominant dark-rum or
greenish hue, and much of it is specked or stained. This type of mica is also common in the southeastern
part of the Franklin-Sylva district, in the Wolf Mountain-Pinhook Gap area. Black-stained mica is rela-tively
uncommon in the district, but staining caused by many minute biotite flakes in the mica is particularly
common in the Caney Fork area of Jackson County.
The quality of some of the mica in the Franklin-Sylva district is lowered by imperfections such as wavi-ness,
mottling and surface stains, haircracks, tangle-sheet structure, and ruling. Ruling and waviness are
related to the faults of small displacement that are widespread throughout the district. "A" structure is
common in the Cashiers district. In the Franklin-Sylva district it is found at many localities but impairs
far less mica than in some other 'domestic mica districts. Wedge "A" mica is abundant in several pegmatites
near Greens Creek, Jackson County.
No clearcut relation has been established between quality of mica and type of mica occurrence or shape
of the enclosing pegmatite body. In general, the irregular pegmatite bodies that contain many tabular in-clusions
of wall rock and only small or scattered quartz masses yield a lower percentage of high-quality sheet
mica than the more sharply defined, discordant dikes that have well-developed quartz cores. Pegmatites
mined predominantly for scrap mica are represented among the large irregular masses—for example the
Iotla-Bradley, Berry, Burr Knob, Big Flint, Annie Laurie, and in large part the Shepherd Knob. Likewise,
pegmatite bodies with similar structures in the Caney Fork area have yielded dark-colored mica that is com-monly
stained.
MINING
HISTORY
Pegmatite mining in the district began with the production of kaolin by the Cherokee Indians, presum-ably
for shipment to England. As early as 1744, an English patent was recorded for the production of
porcelain from an earthy mixture produced by the Cherokee Nation in America, consisting probably of kaolin,
14 See, for example:
Wierum, H. F., and others, The mica industry: U. S. Tariff Commission, Rept. 130, 2nd ser., 1938.
A. S. T. M., Grading and classification of natural mica: Amer. Soc. for Testing Mater., Release D-351-38, 1938.
War Production Board mica releases No. 1 and No. 2, July 6, 1942.
Gwinn, G. R., Strategic mica: U. S. Bur. Mines Inf. Circ. 7258, 1943.
Wayland, R. G., Mica in war: Mining Technology, vol. 8, no. 4, July, 1944.
Billings, M. H., and Montague, S. A., The wartime problem of mica supply; Eng. and Min. Jour., vol. 145, no. 8, pp. 92-95,
1944.
Lintner, E. J., Mica, a war essential mineral: Rock Products, vol. 47, no. 5, pp. 48-50, 92-93; no. 6, pp. 74-76, 114-116, 1944.
16 Mica Deposits of the Franklin-feldspar,
and quartz. 15 Thomas Griffiths came to the Cowee section of Macon County from England to ob-tain
kaolin in 1767. 16 He cleaned out an old pit from which kaolin had been extracted previously, and trans-ported
at least 5 tons of the kaolin to Charleston for shipment to England. Modern kaolin mining in North
Carolina began about 1888 near Webster, in Jackson County. For a number of years the production was
largely from the Franklin-Sylva district, and was small, but about 1900 North Carolina began to gain promi-nence
as a kaolin-producing state. In recent years, North Carolina's entire output has been from the larger
deposits in the Spruce Pine district.
Mica is believed to have been mined by the early Indians presumably for ornamental purposes. Re-mains
of extensive workings of ancient origin are reported to have been found at the Baird mine.17
Sterrett18 summarizes the beginnings of mica mining as follows : "Modern mica mining in North Carolina
was begun in 1867 by L. E. Persons, of Philadelphia, previously of Vermont. Mr. Persons' attention was
directed to Jackson County by someone in Philadelphia who had seen a mica crystal exhibited at the State fair
in Columbia, S. C, in 1858, by D. D. Davies, of Webster. In the autumn of 1867, Mr. Persons went to Jack-son
County and learned from Mr. Davies the location of favorable prospects for mica in Jackson and Hay-wood
Counties, which he soon opened." The Big Ridge mine is generally considered to be the first mica mine
to be developed in the district.
METHODS
The weathered near-surface parts of pegmatites are mined first by pick-and-shovel open-cut methods,
although in some places steam shovels, drag lines, bulldozers, and hydraulic methods have been used in soft
material. Timbering is ordinarily necessary as soon as underground work is begun, as workings cave easily.
The deeper mines encounter hard rock that must be drilled and blasted. Barren rock is not broken unless
absolutely necessary ; hence, many openings are narrow and tortuous.
The pegmatite mining is for mica almost exclusively, although many mines were first developed for
kaolin, and the principal product at the Sally Reed, Lin McCall, McGuire, and Doc Sanders mines has been
feldspar. As a general rule, only one pegmatite body is mined at any one mine. The largest workings for
sheet mica are those at the Big Ridge mine, described on page 28. Some mines have been very productive
although the sizes of their openings are small—for example, the Moody, described on page 42, and the
Beasley No. 1, described on pages 20-22. Doubtless unusually rich mica shoots were mined from these two
mines.
ECONOMIC FACTORS
In the average sheet-mica mining operation, from 5 to 15 tons of rock are moved daily, yielding a few to
500 pounds of mine-run mica. The largest sheet-mica operation in 1942, the Big Ridge mine, yielded about
2,300 pounds of mine-run mica daily, while 29 tons of waste rock were moved to the dump during a 14-man
10-hour shift. Inasmuch as some muck or waste was also left in the mine on lofts, the mine-run mica evi-dently
constituted between 3 and 4 percent of the total pegmatite mined. Additional figures on more recent
output of the Big Ridge mine are given on page 32.
Total mica in the rock mined probably ranges from 3 to 10 percent at most good mica mines, but if mine
scrap and mica too small to be recovered are excluded, the mine-run mica probably ranges from about one to
four percent of the rock mined. The decomposed pegmatites at the Iotla-Bradley and Shepherd Knob mines
are estimated to be 10 to 12 percent muscovite, but their content of scrap mica is exceptionally large. The
output of a typical sheet-mica mine, under pre-war conditions which permitted the inclusions of much low-grade
material in the sheet and punch mica, consisted of about 80 percent scrap, 15 to 16 percent punch, and
4 to 5 percent sheet mica. Different standards of quality and preparation during the war have brought about
a diminution in the percentages of sheet and punch mica recovered. Table III shows the proportions of punch,
circle, and various sizes of sheet in nearly 2,000,000 pounds of mica produced from 12 mica mines in the
Franklin-Sylva district during the period 1922-42, and similar figures for the Big Ridge mine. These indi-cate
what sizes might be expected in the future from the better mines in the district. Scrap mica generally
averages 65 to 95 percent of the total mica produced.
15 Watts, A. S., Mining and treatment of feldspar and kaolin in the Southern Appalachian region: U. S. Bur. Mines Bull.
53, p. 10, 1913.
18 Ceramic Age, vol. 14, no. 5, pp. 165-169, November 1929.
17 Smith, C. D., Ancient mica mine in North Carolina: Smithsonian Inst. Rept., pp. 441-443, 1876.
18 Sterrett, D. B., op. cit., p. 167.
Sylva District, North Carolina 17
The proportion of high-quality sheet and punch mica to the total mine run has become increasingly im-portant
as a factor in mining, because of the increased demand for such qualities during the war. The mica
is classified quantitatively according to percentages of No. 1, No. 2, "No. 2 inferior", and No. 3 grades. The
proportion of Nos. 1, 2, and "2 inferior" to the total mine run averages only a few percent, rarely exceeding
12 percent, but upon this ratio depends to a great extent the value of the total mine-run mica.
SCRAP MICA
Scrap mica is obtained in the Franklin-Sylva district both as a by-product from sheet-mica mining and
from decomposed pegmatite mined chiefly for scrap mica by pick-and-shovel, power shovel, or drag-line
methods. In 1942, three plants for recovery of scrap mica were in operation near Franklin, utilizing ma-terial
from large open cuts in weathered pegmatite and from dumps of previous sheet mica mining opera-tions.
In 1944 scrap mica was being produced by the following concerns
:
(1) Bradley Mining Company, and (2) Duvall and Liner, both at Iotla Bridge on the Little Tennes-see
River.
(3) Fred Arnold (Arnold Mines) plant about one mile southeast of Iotla Bridge, on the Little Ten-nessee
River.
(4) The Franklin Mineral Products Company mica grinding plant in Franklin.
The feed for the several scrap mica washing plants is either decomposed pegmatite or dump material
from old mica mines. The decomposed pegmatite used in the summer of 1944 was mined from the Iotla-
Bradley and Shepherd Knob pegmatites, and is reported to have averaged about 10 percent muscovite. The
large pegmatites rich in small mica have been best suited to this purpose—for example the Shepherd Knob
(pi. 17), Iotla-Bradley (p. 37), Berry, and Big Flint (p. 26).
FELDSPAR
In the Franklin-Sylva pegmatites feldspar is at present the only mineral of commercial value other than
mica. The relatively low price of crude feldspar does not permit profitable production where mining or
transportation costs are high ; accessibility and haulage facilities are more significant economic factors than
in mica mining. Feldspar mining has seldom been profitable in the Franklin-Sylva district because of the
low unit value (about $6 to $7.50 per ton) and the high cost of transportation to the nearest market at
Spruce Pine, about 100 miles distant. Pegmatites suitable for feldspar mining are more sparsely distributed
in the Franklin-Sylva district than at Spruce Pine, but coarse potash feldspar is abundant in some pegma-tites,
particularly several in the Pinhook Gap-Wolf Mountain area of Jackson County.
Feldspar has been produced since about 1933 near Bryson City, in Swain County, adjoining the Franklin-
Sylva district on the northwest. Prior to the summer of 1945 this feldspar had been shipped to Spruce
Pine either by rail or truck. In the fall of 1945 a feldspar grinding mill was put into operation at Dillsboro
and plans were under way for the construction of another at Bryson City.
PAST PRODUCTION
Reliable and complete production figures for the Franklin-Sylva district are not available for years
prior to 1942. Minerals Yearbook19 lists the annual production of combined sheet and punch mica for the
State of North Carolina, shown in Table II for the period 1920-44. Purchase records of the Asheville Mica
Company, buyers of nearly all of the mica in the district, were also consulted and provided the most accurate
basis for estimating the amount of mica produced by the district during the period 1922-42. During this
period, sales of mica were made from more than 75 mines ; a summary of the approximate total production
of 12 of the mines for which the records are most complete is shown in Table III.
The 12 mines whose production is shown in Table III produced most but by no means all of the mica
from the district during the years 1922-42, for at least 75 mines were active at times during this period.
The total for the 12 mines, 1,998,266 pounds of sheet and punch mica, can be compared with the State's
total for a similar 21-year period 1920-40, for which production figures are available. During the period
1920-40 North Carolina's output amounted to 13,263,462 pounds of sheet and punch mica, valued at $2,557,511
(table II). From these figures it is estimated that the annual production of sheet and punch mica in the
Franklin-Sylva district during the period 1920-40 was nearly 20 percent of the total for the State, or nearly
126,000 pounds of sheet and punch mica annually. Most of the remainder of North Carolina's output, prob-ably
about 75 percent of the total, has been obtained from the Spruce Pine district.
U. S. Bur. Mines, Minerals Yearbook.
18 Mica Deposits of the Franklin-table
ii
Recorded Production20 of Sheet and Punch Mica from North Carolina,
Year Amount (Pounds)
1920.
1921.
1922.
1923.
1924.
1925..
1926..
1927..
1928.
1929..
1930..
1931..
1932..
1933..
1934..
1935-
1936-
1937-
1938-
1939..
1940..
1941-
1942..
1943..
1944..
1,084,946
230,532
544,495
1,130,283
597,385
592,478
700,313
665,360
777,395
894,200
749,074
389,426
127,696
162,672
293,381
512,590
730,446
1,044,328
632,646
401,170
1,002,646
1,614,863
1,654,895
1,901,120
814,874
1920-44
Value
$405,654
51,851
119,767
188,317
108,656
105,376
150,362
114,514
129,706
150,293
112,451
51,657
18,322
21,107
38,674
77,598
119,653
218,176
87,879
69,344
218,154
318,783
505,634
1,772,324
1,530,625
20 U. S. Bur. Mines, Minerals Yearbook.
TABLE III
Approximate Production of Sheet and Punch Mica from the Big Ridge and 11 Other
Mines in the Franklin-Sylva District, 1922-42
Size of sheet
Big Ridge mine21 12 of the principal producers
including Big Ridge
(inches)
Pounds Percent of
total sheet
Pounds
Percent of
total sheet
8 x 10-
6 x 8
74
852
11,228
24,409
19,532
35,361
99,479
83,894
146,338
0.02
0.21
2.79
6.01
4.73
8.33
23.24
19.92
34.75
83
1,016
12,747
27,865
23,278
41,664
117,402
102,816
173,780
0.02
0.20
2.54
5.56
4 65
4 x 6
3 x 5
3 x 4
3 x 3 8 32
2 x 3 23 45
2 x 2 20 53
iy2 x 2.... 34 73
Unclassified sheet 10,000
Total sheet 421,167
763,505
Percent of
total sheet,
circle, and
punch
35.55
64.45
510,651
1,372,497
115,118
Percent of
total sheet,
circle, and
punch
25 56
Total punch 68 69
Total circle 5 75
Total sheet,
circle, and punch 1,184,672 100.00 1,998,266 100.00
21 Published by permission of K. A. Sprague, Haywood Lumber and Mining Company.
Sylva District, North Carolina 19
Production of high-quality mica under conditions of heavy demand and intensive mining activity during
the war years, 1943-1944, is shown in Table IV. The amounts shown for 1942-44 cannot be compared di-rectly
with the figures for previous years because of the differences in quality of preparation and grading.
The pre-1942 data apply to half-trimmed sheet mica (1^2 by 2 inches and larger), both clear and stained,
and untrimmed punch (1V4 inches in diameter). The mica sold to Colonial Mica Corporation since 1942 has
been three-quarter trimmed and full-trimmed sheet (IV2 by 2 inches and larger) and full-trimmed punch
(1 by 1 inches and larger) of No. 1 and No. 2 qualities, which exclude much heavily-stained mica.
FUTURE POSSIBILITIES
The history of past production of the district is the most reliable basis from which to estimate possi-bilities
of future production. The average annual production during the years 1920-40 is estimated to be
nearly 126,000 pounds of sheet and punch mica of all qualities. The monthly average of 10,500 pounds of
high-quality sheet and punch mica during the last half of 1944 (see table IV) indicates the potentialities of
the district under intensive development. This rate of production could probably be maintained for at least
several years by the continued operation of productive mines and the development of other prospects as the
table IV
Production of Mica of Qualities Acceptable by Colonial Mica Corporation
in the Franklin-Sylva District, 1943-4422
Period Pounds Sheet
Oct.-Dec. 1943 24,578.49
Jan.-June 1944 51,599.79
July-Dec. 1944 63,004.62
Total Oct. 1943-Dec. 1944 139,182.90
23 Published by permission of Colonial Mica Corporation.
more productive mines become depleted. An increase would probably result from the development of addi-tional
headings at some of the better mines.
DESCRIPTIONS OF SELECTED MINES
ALLMAN COVE MICA MINES
J. M. Parker III
The Allman Cove group of mines is 1^4 miles northwest of the center of the town of Franklin, in the
east-central part of the Franklin quadrangle. The mines lie on low ridges west of North Carolina Highway
28, from which they are easily reached over half a mile of good dirt road. The group includes the Allman
Cove mine, the Mudhole mine, and the Willis mine.
The earliest work at the Allman Cove mine was done about 1870 or 1880. Surface mining was done
and a long adit was driven northward from the creek. (See pi. 3.) About 1904, the large pit at the west
end of the workings was worked for kaolin to a depth of about 60 feet. The mine has been worked intermit-tently
by many operators. Mica suitable for condensers and telephone equipment is reported to have been
produced in 1918 or 1919. Since 1925 operations have been nearly continuous and have been carried on
mainly by John and W. P. Brindle, John and Floyd Tallent, and J. W. Roper. The mine was worked be-tween
January and March 1943 by F. E. Snow and E. B. Ward, and then until the summer of 1943 by Mr.
Snow.
The Mudhole mine was first explored about 1930 by John Tallent. The last operation, by Tallent and
Roper, was abandoned in 1942 when the shaft became dangerous and the volume of water became difficult
to handle.
The Willis mine was worked first by Fred Willis, about 1926, and more recently by John Tallent and
Ivy Crisp, the present owner. In July 1943, F. E. Snow drove a tunnel westward along the dike below the
earlier workings.
The Allman Cove mine consists of three large and several small pits, at least 16 shafts ranging in depth
from about 15 to 90 feet, and many short drifts at various levels. The underground workings are now in-accessible,
except the deep shaft and stopes at the east end. It is judged from reports that the pegmatite
may have been almost completely worked out down to water level, which is 50 to 70 feet below the surface,
a little above the altitude of the creek to the south.
The pegmatite body is nearly divided into two parts by a projection of wall rock (mica gneiss) near the
middle of the workings. The pegmatite body thickens both east and west of this point. The eastern part
trends east and is nearly vertical. In the easternmost shaft the pegmatite is only 18 inches thick, but it is
nearly 30 feet thick in the main workings, and about 20 feet thick in the large pit. The west part of the
pegmatite trends N.70°W. and probably dips steeply to the south. It is about 20 feet thick and probably
tapers out at the southeast end and branches into several stringers at the northwest end. The pegmatite is
intrusive into mica gneiss ; in general it lies parallel to the strike of the foliation but in places cuts across it.
The pegmatite is composed of partly kaolinized feldspar (probably plagioclase), quartz, muscovite, and
biotite. The eastern part of the pegmatite contains a number of irregular streaks of "burr rock", which has
been described on page 9. All of the mica seen in the east workings was small, wavy, ruled, and cracked.
Most of it was scrap but a little would yield punch or sheet up to about 2 by 2 inches. The mica was moder-ately
stained by clay and iron oxide, and intergrowths with biotite were abundant.
The underground workings at the west end were flooded and could not be examined ; hence the following
description of this part of the pegmatite is based upon reports by miners. A well-defined quartz mass, 2 to
at least 3 feet thick, in part "burr rock", lies in the middle of the pegmatite body. Sheet mica has been
found on both sides of it, but most of the mica is along the south wall. The mica occurs in larger books at
this end than at the east, but it is considerably ruled. Flat, hard, clear, dark-rum mica is produced. Very
little biotite is found.
BEASLEY No. 1 MINE
M. R. Klepper and J. C. Olson
The first work at the Beasley No. 1 mine is reported to have been done in the main open cut about 1880
or 1885. A large amount of mica is said to have been mined from an unusually rich pegmatite vein during a
period of several years. The old dumps were later reworked for scrap mica. After many years of idleness,
Sylva District, North Carolina 21
BULLETIN 49 PLATE 3
(Dota from F. E. Snow)
1926' Level
— 2000
I960
— I960
— 1940
1920
area shown on
underground maps
Scale in feet
Contour interval 10 feet
Datum assumed
EXPLANATION
Muck
Pegmatite, undivided
Scrap mica
Quartz- muscovite pegmatite ("burr"]
Mica gneiss
"eo Contact, showing dip
Contact, approximate
'' Trace of pegmatite body
(cave^^xT^
^ Outline of underground workings
27
B Shaft, showing depth in feet
a Foot of raise
to Rim of open cut
Mapped by J M.Parker III ond V.'C.Fryklund, Jr. June- July 1943
Map and Sections of the Airman Cove Mine, Macon County.
22 Mica Deposits of the Franklin-the
mine was leased in June 1943, to the Thurman Mining Company, which developed all of the west open-cut.
This operation was abandoned about the end of April 1944.
The country rock is garnetiferous biotite gneiss with some layers of quartzose mica gneiss. The foliation
strikes N.65°E. on the average and dips 25°N. to vertical. Steep southerly dips occur at several places in the
southern part of the area. The change from northerly to southerly dips takes place near the main pegmatite
vein; within a few feet of the contacts the gneiss is severely contorted and contains much pegmatitic or
granitic material. The pegmatite evidently was emplaced in a fault or zone of sharp folding. A vertical
pegmatite 3 inches thick, which is exposed in the stripped area above the west open-cut, sharply cross-cuts
the foliation of the gneiss. It was probably emplaced in a fracture.
The main open cut and the west cut (pi. 4) are in different pegmatite bodies. Both pegmatites are very
irregular, with general easterly strikes and southerly dips. Pegmatite offshoots that extend into the wall
rocks are both discordant and conformable with the foliation.
Pegmatite in west cut.—The pegmatite in the west cut strikes east and dips 55°S. From a maximum
thickness of 12 feet in the face, it pinches upward and eastward to about a foot at the edge of the cut, where
it consists mostly of quartz. It is made up of three principal rock types. (1) Oligoclase-rich pegmatite, con-taining
biotite, muscovite, quartz, and garnet, occurs in zones 1 to 4 feet thick adjacent to each wall of the
pegmatite body. (2) Quartzose pegmatite occurs within the oligoclase zones as layers 1 to 7 feet thick.
(3) Muscovite-rich pegmatite occurs in a zone about 2 feet thick in the center of the pegmatite, and less
prominently near the hanging wall.
Biotite is relatively abundant in part of the oligoclase pegmatite near the footwall and with muscovite
and quartz in the central part of the pegmatite. Pyrrhotite and apatite are also present.
Most mica in the west cut is clear ruby, but a little is green. Most of the green mica is black-specked,
reeved, warped, and broken. Some of the ruby mica is lightly specked, but most is clear. The principal de-fects
are "A" structure, warping, and ruling.
Pegmatite in main cut.—The main pegmatite body is one-half to one foot thick at the west end of the
main cut, but thickens eastward. The part of the pegmatite that is 5 feet or more thick has a strike length
of about 100 feet ; it swells to more than 15 feet in thickness midway along this length. The dip is steep in
the open cut, but decreases southward in the stope to less than 45°. Many who know the history of the mine
describe the pegmatite as an unusually rich "pocket", suggesting that the pegmatite thins down-dip as well
as along the strike.
Only a thin rind remains along each wall of the pegmatite in the main cut. This zone is very rich in
scrap mica, especially along the hanging wall. Almost all the mica books are less than 2 inches in diameter,
and are interlocked in pegmatite that also contains a little oligoclase and quartz. The core of the pegmatite,
near the middle of the open cut, is reported to have been a thick mass of quartz. Mica is reported to have
been unusually abundant along the margins of the central quartz body. This quartz mass was thickest in the
part of the pegmatite at the middle of the main open cut, and thinned out to the east and west. Near the east
end of the area, the pegmatite feathers out into several narrow stringers that contain only scrap mica. Other
offshoots extend westward from the main cut. Two of these are very rich in scrap mica; one has been ex-plored
by the adit and the other, which is 1 foot thick, is exposed at the west end of the cut.
Mica from the main cut was probably of better quality than that from the west cut. It is mostly clear
ruby. Although "A" structure and other physical defects are present, they are not as prominent as in mica
from the west cut. Very little biotite occurs in the main pegmatite.
BEASLEY No. 2 MINE
M. R. Klepper and E. Wm. Heinrich
The Beasley No. 2 mine is 8 airline miles N.25°E. of Franklin. It lies near the head of an unnamed
branch on the north side of Caler Fork Valley, at an altitude of 3,150 feet. The mine is reported to have
been operated by the Bowers brothers of Franklin in 1890, and has been worked intermittently up to the
present time. It is owned by the Masonic Lodge of Franklin, who leased it in the summer of 1942 to the
Asheville Mica Company of Biltmore, N. C. Operations were begun on September 1, 1942.
Sylva District, North Carolina 23
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The old workings consist of 8 surface cuts, a shaft caved at a depth of 13 feet, an inaccessible inclined
shaft, an adit caved 40 feet from the portal (Adit C), and another adit (Adit B) that opens into drifts and
stopes. (See pi. 5.) The stopes, now accessible only in their lower parts, were first worked from the in-clined
shaft and later connected with Adit B. From September 1942, to May 1943, the pegmatite body was
mined in the drift and stopes from Adit B. Adit A was begun in May 1943, and reached the pegmatite in
June. By May 1944, overhand stopes from this adit had been connected with underhand stopes from Adit B.
The country rock is banded biotite gneiss. In the northern part of the area the foliation strikes a few
degrees north of east and dips steeply north. The foliation of the rock in the southern part of the area has a
similar strike but dips to the south. These relations suggest a tightly folded anticlinal structure, the axis of
which trends nearly east. The pegmatite body strikes a few degrees north of west and dips on the average
45°SW. It has been explored over a strike length of 370 feet and over a vertical distance of 250 feet. The
thickness ranges from 21/2 to 12 feet, with an average of 8 feet.
Some parts of the pegmatite body are well zoned. An average section from hanging wall to footwall in
the zoned part of the pegmatite is as follows
:
Pegmatite Thickness
Medium-grained quartz-feldspar
pegmatite ; no muscovite 6" to 1'
Pegmatite rich in coarse muscovite;
remainder chiefly feldspar (plagioclase?) 1' to l 1/^
Coarse plagioclase, with very little
quartz or muscovite 2' to 2y2
'
Muscovite-biotite selvage 3" to 6"
Massive quartz 3' to 4'
Medium-grained quartz-feldspar pegmatite
locally containing small books of muscovite 6" to 1'
The quartz core, which plunges southeast at an angle of about 35°, has a horizontal width of about 120
feet. The core and the accompanying muscovite zone are absent from the exposures in the surface cuts and
the higher accessible parts of the stopes. Here a rough three-fold layering is present; a narrow selvage of
barren quartz-feldspar rock occurs along both walls, and the remainder is plagioclase-rich pegmatite that con-tains
biotite and muscovite.
West of the end of the quartz core on Level Z (pi. 5, underground map) the drift passes through a 25-
foot zone of hybrid pegmatite which contains numerous inclusions and septa of biotite gneiss. Beyond this
zone of hybrid pegmatite the body contains a core of very coarse-grained quartz and feldspar and a rudi-mentary
muscovite zone near the hanging wall. The quartz core also ends near the eastern face of Level Y.
Between the end of the quartz core and this face the pegmatite body thins from 7 to 2y2 feet, and it may
possibly pinch out toward the east.
Muscovite occurs in a well-defined zone between the barren hanging-wall rind and the zone of coarse
plagioclase. A thin selvage of muscovite with biotite lies along the hanging-wall side of the quartz core,
but this mica is too severely broken to be of strategic value. The lateral extent of the mica zone appears to
coincide with that of the quartz core, and both the mica shoot and the core plunge about 35° southeast. Mica
books are as much as 2 feet wide and 3 inches thick ; ribbons 16 inches long and 5 inches wide were also noted.
Ruling, warping, and cracks are the principal defects ; "A" structure and mineral inclusions are subordinate.
The mica is deep rum and the books are generally hard and flat. Much of it is of very good quality. Flat
sheets measuring 6 by 8 inches were trimmed from some of the larger books.
The following estimates and calculations are for the period between December 27, 1943, and May 26, 1944
:
Total pegmatite mined 1200 tons
Pegmatite mined per average day 9 tons
Mine-run mica produced per average day 400 pounds
Percentage mica in pegmatite* J 2.2%
Total mine-run mica produced 25.5 tons
Total No. 1 and No. 2 sheet and punch mica
produced** 6000 pounds
Percentage of No. 1 and No. 2 sheet and punch
mica in mine-run, calculated 12 %
Percentage No. 1 and No. 2 sheet and punch
mica in mine-run, estimated average 8%
•Allowing for loss on dumps.
Probably includes some mica produced before December 27 and sold after that date.
Sylva District, North Carolina 25
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26 Mica Deposits of the Franklin-
BIG FLINT MINE
E. Wm. Heinrich
The Big Flint mine, also known as the Grassy Ridge mine, is 2 airline miles S.57°E. of Balsam, Jackson
County. The mine lies 200 feet above and 300 feet northwest of the northern branch of Cabin Creek on the
southeast flank of Grassy Ridge, and about half a mile southwest of the Haywood County line. The property
is owned by the heirs of the Tom Lee Estate of Waynesville. W. W. Davis of Waynesville leased the pro-perty
in 1932 and operated it as a scrap-mica mine until August 1942. A scrap plant, consisting of bins, two
crushers, conveyor flumes, and a dryer, was constructed. In August 1942 Davis sold out to the Balsam Min-ing
and Milling Company, which operated the mine for both sheet and scrap mica until December 15, 1943.
Fred Lewis of Hazelwood secured the lease on March 1, 1944, and attempted to operate the property for
sheet mica and washer stock. This operation did not prove successful and Mr. Lewis ceased work early in
May 1944.
Surface workings (pi. 6) consist of three large irregular open-cuts arranged along a line that trends
N.65°E. The underground workings consist of three adits, a level of irregular drifts and crosscuts, several
large stopes, and several winzes and raises. Adit A was worked by Fred Lewis ; all the other workings are
old, and were dug either during or before the period of operation by W. W. Davis.
The country rock is a fine-grained, locally garnetiferous, biotite gneiss. It is conspicuously contorted,
especially near contacts with the pegmatite mass. The rock has been intruded by a very large body of peg-matite
with a minimum width of 300 feet and an explored strike length of 375 feet. The northwestern con-tact
of the body, which is well exposed, has a general trend of N.60°E. In Cuts I and II the contact has a
general steep dip to the southwest, but in Cut III it is reversed to steeply southeast. Along the southwestern
wall of Cut III are exposed several thick bands of gneiss, which suggest a proximity to the southwestern con-tact.
In general the pegmatite body cuts across the foliation of the gneiss.
The pegmatite body contains a large body of massive quartz which forms a prominent white outcrop be-tween
the two northern cuts. The quartz body widens toward the southwest and ranges in thickness from a
few feet to 65 feet. It is 130 feet long, is exposed over a vertical distance of 85 feet, strikes N.45°E., and
dips steeply northwest. At its northeastern end 4 feet of barren pegmatite separates the mass from the
northwestern contact with the gneiss ; in the northwestern arm of Level D the quartz body is in contact with
the gneiss, but at the southwest end of the mass 45 feet of pegmatite lies between it and the gneiss.
Along the footwall of the quartz body is an unusual mineralogic zone consisting of innumerable sub-parallel
and shard-like slabs of quartz, which range in thickness from a fraction of an inch to nearly a foot
and are separated from one another by films of biotite that give to the rock a strongly foliated appearance.
Generally the slabs and films are parallel with the footwall of the quartz body.
The bulk of the pegmatite body is a medium-grained aggregate of quartz, feldspar, muscovite, and biotite.
Although some of the biotite occurs in thin strips as much as 3 feet long, the percentage of biotite in the body
as a whole is low. Most of the muscovite occurs in small flakes and books rarely over 1 inch in diameter.
Both microcline and plagioclase are present and the latter is generally more kaolinized. Plagioclase appears
to be the more common feldspar near the northwest contact, but in the central part of the pegmatite micro-cline
is more abundant.
Two well-defined zones of coarse mica occur in the pegmatite body, one along the footwall contact of the
quartz mass and the other along the northwestern contact with the gneiss. The quartz footwall zone has been
extensively mined in the underground workings. It has a maximum thickness of 3 feet, and books of mica
as much as 5 inches in diameter have been observed in it. This zone appears to be very persistent and the
quantity of mica obtained from it appears to have been large. The zone along the northwest contact with the.
gneiss was mined in Adit A. This zone is discontinuous and consists of scattered concentrations of mica over
a width of 7 feet. Books as much as 9 inches in diameter were obtained from this zone.
The principal defects of the mica are closely-spaced ruling, persistent and through-going fractures, a
light-green mottling, and dark spots and minute inclusions of biotite. Because of the cracks and ruling, even
the largest books will yield only small sheets or punch.
The mine has been a large producer of scrap mica and considerable quantities of pegmatite rich in scrap
mica remain to be mined. The richest concentrations of scrap mica occur in a belt that is parallel to the
Sylva District, North Carolina 27
BULLETIN 49 PLATE 6
4600
1
A
V * 2j 1
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ALONG LINE A-A'
4560
4540
4520
CROSS SECTION
A
V
A'
4500
4*480
ivi V
Scole in feel
Contour Intervol ten feet
Ootum from U.S.G.S Cowee Quadrangle
ftonttable survey Mapped by E.wm.Heinrteh, MR.Ktepper, ond L-C.Pray April 1944
Revised by E-Wm.Heinrich March 1945
EXPLANATION
E3 Qucrtz-biotite pegmatite
E23 Muscovite pegmatite m Quorlz-plogioclose pegmatite m Quartz- plagioclose-muscovite pegmatite
103 Coarse microcline
ED Mossive quortz
ra Biotite gneiss
sy Contact wiln dip
*** Approximate contact
-" Contact between pegmatite units
s Attitude of pegmatite ploty structure
-<•
J7
Attitude of foliation
Limit of exposure
4^ Rim of open cut
M Foot of dump
.^ Outline of adits
Outline of Level and Slope E -
Map and Sections of the Big Flint Mine, Jackson County.
28 Mica Deposits op the Franklin-trend
of the pegmatite body and has a width of about 80 feet along the northwest side of the mass. This belt
is estimated to contain between 5 and 10 percent of scrap mica. Beyond this width the content of scrap mica
is markedly less. The transition to the scrap-poor part seems to be accompanied by an increase in the per-centage
of microcline.
BIG RIDGE MINE
M. R. Klepper and E. Wm. Heinrich
The Big Ridge mine is 3.9 airline miles S.21°E. of Hazelwood, Haywood County. It lies on the south-west
slope of Roberson Ridge on a rounded nose between two unnamed branches of Deep Gap Creek. Most of
the workings are at altitudes between 4,500 and 4,700 feet. The Big Ridge mine is believed to be the oldest
mica mine in North Carolina on the basis of continuous operation. From 1922 to 1944 it yielded at least
436,000 pounds of sheet mica and 807,000 pounds of punch mica.
The first prospect pits are reported to have been dug near the old caved shaft. (See pis. 7 and 8.)
In 1915 J. E. Burleson began the lower adit ; by 1944 it had been advanced to a length of 1,060 feet and had
been stoped over 650 feet of this length. The mine is owned by the Haywood Lumber and Mining Company
of Waynesville, and for the last ten years it has been under lease to T. L. Blalock of Hazelwood.
The Big Ridge pegmatite body is an irregular dome-shaped intrusive, the long axis of which trends
N.55°E. The body has been mined from a series of interconnected drifts, stopes, and chambers over a length
of 650 feet, and over a maximum width of 300 feet. The vertical extent of the workings is 200 feet. This
maze of workings is oval in plan and asymmetrically arch-shaped in both longitudinal and tranverse sections.
(See pi. 8.)
The top of the pegmatite dome (fig. 2) is nearly flat with a shallow elongate central depression parallel
to the long axis of the dome. Distinct ridges border this central depression. The general domal shape of the
mass is interrupted by numerous apophyses, which project upward from the top, and by a large off-shoot
from the southwest side. At the southwest end of the workings the top of the dome narrows and plunges
steeply southwest. For about 200 feet east of this steeply plunging nose the upper half of the south flank of
the dome dips to the northwest and the lower half is vertical or dips steeply southeast. (See pi. 8.) Toward
the east the dip of the south flank becomes vertical, then gradually changes to steeply south, and finally to
moderately south. The dip of the northwest flank of the dome decreases from about 70 °W. at the nose to
about 30°NW. near the northern end of the workings.
The thickness of the pegmatite ranges from 2 to 25 feet. It is thickest around the steeply plunging nose
and the marginal ridges of the top, and thins along the flanks, except at junctions with apophyses. The hang-ing-
wall contact along the northwest flank of the dome is step-like in structure, consisting of alternating
steeply dipping "risers" and nearly horizontal "treads".
The main rock types that occur are biotite gneiss, pegmatite, granite, and a felsitic dike rock. In addi-tion,
gradational or hybrid rock types occur between pegmatite and gneiss, pegmatite and granite, and gneiss
and granite. The gneiss, into which the pegmatite has been intruded, consists of fine- to medium-grained
quartz, biotite, and a little garnet. It occurs chiefly along the outer contact of the pegmatite. The foliation
strikes northwest and dips southwest. The pegmatite is simple in mineral composition, containing plagio-clase,
quartz, biotite, and muscovite, with very minor quantities of microcline. The accessory minerals are
apatite, pyrrhotite, ankerite, and hedenbergite. Except for concentrations and zones of mica-rich pegmatite,
the mass as a whole is very poorly differentiated. Small discontinuous quartz lenses were observed in only
two places. The order of abundance of the minerals in the pegmatite is estimated to be : plagioclase 73 % ;
quartz 20% ; muscovite 3% ; biotite 3% ; others 1%. The main mass of pegmatite consists of a coarse-grained
intergrowth of plagioclase, quartz, biotite, and muscovite. The proportion of biotite varies widely
and sheets of the mineral are locally arranged perpendicular to the contacts with the gneiss.
The granite is a uniformly medium-grained rock consisting of gray plagioclase, biotite, muscovite, and
quartz, in that order of abundance. The rock has a slight foliation due to the orientation of biotite flakes, but
the percentage of biotite varies widely. The granite occurs as discontinuous masses along the inner margin
of the pegmatite mined, which in most places is the footwall. Small pods and lenses of granite also occur
locally within the pegmatite body itself. The largest body of granite, which occurs below the nose of the
Sylva District, North Carolina 29
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Fig. 2.
—
Structure Contours on Top of Pegmatite Body, Big Ridge
Mine, Haywood County.
pegmatite, is known to have a vertical extent of 100 feet and a thickness of at least 60 feet. This mass
appears to thin along both flanks of the pegmatite, but the exact footwall contact of the granite with the
gneiss is nowhere exposed. The pegmatite and the granite appear to be closely associated in origin, as
transitional rock types between the two were observed. Large crystals of plagioclase, biotite, muscovite,
and apatite lie entirely within the granite or extend across contacts between the two rocks. In general, how-ever,
contacts between these rocks are sharp, and locally small tabular dikes of granite cut across the peg-matite
body. The crystallization periods of the granite and the pegmatite apparently overlapped.
The youngest rock in the deposit is a felsite, which occurs in tabular dikes, as much as 6 inches thick,
transecting both pegmatite and gneiss.
The quantity of mica in the pegmatite varies considerably in different parts of the mine. In general the
best concentrations of mica have been found where the pegmatite is underlain by granite. Pegmatite around
the nose of the body and along the southwestern two-thirds of the southeast flank is reported to have been
unusually rich in mica. Pillars in this part of the mine show a mica-rich zone from 6 inches to 2 feet thick
along the contact between the pegmatite and the granite. The zone contains from 10 to 40 percent of mica in
books as much as 18 inches in diameter. The zone appears to fade out toward the northeast along the south-east
flank, and there is no evidence for the existence of such a zone either along the top of the pegmatite dome
or in the northwest flank. The mica in the dome and northwest flank of the body appears to have been
rather uniformly distributed throughout the pegmatite.
Sylva District, North Carolina 31
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The mica is light rum to greenish rum ; its principal defects are warping, small dark-brown to black
mineral inclusions, green color mottling, cracks, and some ruling. Although the mica is commonly associated
with biotite, intergrowths of the two minerals are not common. The mica books are hard, split well, and
are generally free from reeves and "A" structure. It is reported that the mica obtained from around the
nose was of somewhat better quality than mica from the flanks of the body. For the period November 10,
1942 to May 4, 1944, the percentage of mine-run mica in pegmatite was 2.8 and the percentage of No. 1 and
No. 2 sheet and punch mica recovered from the mine-run was 8.6.
BOWERS MINE
D. M. Larrabee and E. Wm. Heinrich
The Bowers mine is 3*^ airline miles S.41°W. of Cullowhee, Jackson County. It lies 2,000 feet north-west
of Presley Creek on a steep east-facing slope, at an altitude of about 3,000 feet. The deposit was
discovered in 1899 and has been intermittently operated to the present time. In 1929 it was purchased by
R. U. Garrett of Sylva, who sold it to the Rubin and Hetkin Mica Company of Sylva. This company operated
the property for 18 months ; it was then sold to Philip Godley of Pittsburg, Pa., who worked it for about 6
months. The mine was repurchased by Garrett and again sold to the Rubin and Hetkin Mica Company, who
have continued operations to the present time.
The workings consist of a narrow open-cut 150 feet long and 15 feet in average width. (See pi. 9.)
From this cut stopes, drifts, and inclines, all interconnected, extend to the west and southwest. The differ-ence
in altitude between the highest lip of the cut and the lowest underground workings is 140 feet.
The country rock, a banded garnetiferous quartz-biotite gneiss, strikes generally northeast and dips from
80° southeast to 60° northwest. This rock has been injected by a pipe-like body of pegmatite, which strikes
N.35°W. and dips 80° southwest on the average. The top of the body is well exposed in an irregular drift
from the top of the open cut, and it probably plunges at a moderate angle to the northwest.
The pegmatite contains a quartz core associated with minor quantities of white, blocky microcline. This
core is surrounded by zones of medium-grained plagioclase-quartz rock containing scattered books of musco-vite.
The accessory minerals, which are commonly found near the contact with the gneiss, are garnet, pyrite,
and pyrrhotite. Plagioclase associated with the sulfides is stained a deep green.
Mica occurs in pipe-like bodies in "rolls" along the hanging-wall contact with the gneiss. These bodies
plunge 45°NW. and probably reflect the general plunge of the pegmatite mass. They are known as "barrels"
by the miners, and are as much as 15 or 20 feet thick. Four main "barrels" have been mined, but only one
appears to have persisted throughout the entire vertical extent of the workings. On the 2,936-foot level the
quartz core pinches out toward the west and is supplanted by a central zone of very coarse-grained quartz and
plagioclase. Very little mica was found in this part of the deposit.
The mica is light rum and is cracked and warped. "A" structure, mineral specks, and inclusions are
generally absent, but some of the books contain intergrowths with biotite and others are tanglesheet. The
average mica content of the pegmatite is calculated to be about 2 % ; however, a much higher percentage
may have been present in the richer parts of the pipes. The percentage of sheet and punch mica in the
mine-run is calculated to be between 3% and 4%.
COX MINE
W. C. Stoll
The Cox mine was first opened in 1868 by Judge D. D. Davies and F. S. Orum. The principal opera-tions
since that time were for six months in 1896, 1916-19 and 1925-27 by W. A. Rodgers, 1929-30 and 1935-
37 by the Carolina Mining Company, and 1937-39 by the Asheville Mica Company. L. H. Goodman reopened
the mine during August 1942 but abandoned it in April 1943.
In the main workings, two parallel east-striking pegmatites, referred to herein as the North and South
pegmatites, have been mined for mica. (See pi. 10.) The enclosing wall rock is mica gneiss, the foliation of
which is generally parallel with the pegmatite contacts but locally is transected by them.
Sylva District, North Carolina 33
BULLETIN 49 PLATE 9
PROJECTION ALONG LINE A-A'
E3
inclined mannuo* to
I'.-er levels
\\, ) , 2980' LEVEL
2938 LEVEL
GEOLOGIC MAPS OF
UNDERGROUND WORKINGS
Mopped by D M Lorrabe-.C Wm Henrtch,
and RA.Swomon. 1*13*44
Underground remapped by £ Wm Heinncr.
ond R.WlaiU. 9-12-44
UPPER INCLINE
s>
X
2922' LEVEL
20 40 60 00
SCALE IN FEET
EXPLANATION
Dump (in taction)
Quorlt- feldspar pegmatite
Coarse quo rtz-microc lint pegmatite
Mossive quartz
Sheet mico
Biotite gneiss
Contact, location accurate, shoving dip
Contoct, location approximate
Contoet between pegmatite units
Altitude of (diot'iof.
Limit of eipoure
Rim of open cut
Dump
Upper inclins ^
2960' level
2938* level
2922* level
Outlines of
underground workings,
•V*
Map and Sections of the Bowers Mine, Jackson County.
34 Mica Deposits of the Franklin-
The North pegmatite has been developed over a strike length of 220 feet and a width of 30 to 60 feet, in
an open pit and in underground stopes. The upper contact of this body has the form of an anticline, the crest
of which pitches 10 degrees in a S.68°W. direction. The axes of minor crenulations in the gneiss pitch parallel
to the main structure. The south limb of the anticline dips 50°-60°S., and the north limb, where observed,
dips from 40°N. to 70°S.
The North pegmatite may be divided mineralogically into two principal zones, each of which comprises
two types of pegmatite. The upper zone, 2 to 8 feet thick, is represented either by a mixture of light-gray
plagioclase, light-gray microcline, and quartz or, less commonly, by a mixture of quartz and small books of
muscovite. Shoots rich in book mica lie in the upper zone, but are not coextensive with the zone. In the
stopes underground the upper zone has been mined but the lower zone left in place. The lower zone, 6 feet or
more thick, is mostly massive white quartz, but partly a mixture of coarse microcline with subordinate
quantities of quartz and small scales of greenish muscovite.
The South pegmatite, 40 feet from the North on the main level, has been mined over a strike length of
120 feet and a dip distance of 15 to 30 feet. The walls are curved irregularly, and the dip ranges from 35° to
70°S. The pegmatite body is 7 to 12 feet thick, and consists of light-gray plagioclase, light-gray microcline
in variable amounts, quartz, and a few muscovite blocks.
From the main open-cut and stopes, two parallel series of trenches and small surface workings extend
east-northeast diagonally up the slope. A single series of cuts extends 1,000 feet westward; these cuts ap-parently
were excavated in the South pegmatite. The North pegmatite plunges beneath the surface within
the limits of the main workings, and to the west it lies well beneath the range of surface prospecting.
ENGLE COPE MINE
E. Wm. Heinrich
The Engle Cope mine is 71/2 airline miles S.23°W. of Dillsboro, Jackson County. It lies 1,200 feet above
Savannah Creek and U. S. Highway 23, and about half a mile west of the Cowee sawmill. The mine is under
lease to L. H. Goodman of Biltmore, N. C, who began operations in December 1943. The workings consist of
four large open-cuts, five short crosscuts with drifts, all now partly caved, and numerous small prospect pits
and trenches. The operations by L. H. Goodman have been confined to the large, narrow open-cut near the
center of the mapped area and to an incompleted crosscut 275 feet northeast and 75 feet below this main cut.
(See fig. 3.) This crosscut was driven for a distance of about 80 feet, but was then abandoned. If the peg-matite
body persists with depth this crosscut should intersect it 120 feet from the portal. In March 1944 the
open-cut had attained a maximum depth of 16 feet and was being deepened over a length of 30 feet and a
width of about 5 feet.
The country rock, which is a fine-grained, garnetiferous biotite gneiss, is highly fractured, and the atti-tude
of its foliation varies considerably. Near the contacts with the pegmatite body the foliation is, in general,
conformable. The pegmatite is a persistent, tabular, sill-like body striking N.5°E. and vertical or dipping very
steeply to the east. It ranges in thickness from 2 to 8 feet, and has been explored over a strike length of
about 1,000 feet.
In general, the pegmatite is poorly differentiated. However, in an old drift 60 feet south of the main cut
the body contains a 4-foot quartz core flanked by zones of medium-grained quartz-feldspar rock. A well-defined
zone of coarsely crystalline muscovite occurs along the western contact with the gneiss, both in this
drift and in the main open-cut. The quartz core is absent from the open-cut, where the main mass of the
body consists of a uniformly medium- to coarse-grained intergrowth of quartz and plagioclase. Near the
west-wall mica zone much of the plagioclase is partly replaced by dark-green sericite. Small red garnets
and small blebs and veinlets of pyrrhotite occur sparingly in the plagioclase. Near the contacts with the peg-matite
body the gneiss contains thin films of both pyrite and pyrrhotite.
Mica occurs in a west-wall (generally the hanging-wall) zone. This zone, which is well defined both in
the main open cut and in the old drift south of the cut, is poorly defined in the workings at the northern end
of the area. In the cut this zone has a maximum width of 2 feet and books of mica as much as 7 inches in
diameter were observed in it. At the north end of the cut this zone was estimated to contain between 5 and
8 percent of book mica.
Sylva District, North Carolina 35
BULLETIN 49 PLATE 10
—2540
A A'
ys^
TK ^^
-2500
SECTION A -A' \
Muck
Massive quartz
Sheet mica concentration
Microcline-plagioclase -quartz pegmatite
Plagioclase-microcline- quartz pegmatite
Quartz with small (1/4-1/2") mica flakes
Ptagioctase with garnet and quartz
Contact, location approximate
Contact between pegmatite units
Strike and dip of foliation
Strike of vertical foliation
pitch of axis of small synclinal fold
Limit of exposure
Outline of underground workings
Outline of stope at waist level
Shaft
Dump
( burr )
Rim of open cut
Scale in feet
(for map of main workings ond sections)
40 C
Mapped by W. C. Stolt and J. J. Norton
February 1943
Scale in feet
Contour interval 20 feet. Datum assumed.
Map and Sections of the Cox Mine, Jackson County.
36 Mica Deposits op the Franklin-
Dump (in section)
Quorlz-feldspor pegmotite
Massive quartz
Sheet mica
j 1 Biotite gneiss
J^"" Contact, locotioo accurate, showing dip
-—
' Contoct, location approximate
Contact between pegmatite units
s<7s Attitude of foliotion
Limit of exposure
Outline of underground workings
j<^ Rim of open cut
*""""'"" Margin of dump
PLAN OF 3368' LEVEL
OF MAIN CUT
A'
CONTOUR INTERVAL 10 FEET
DATUM ASSUMED
Mapped by E.Wm.Heinrich and M.R.KIepper
3-8-44
—3400
-3380
4o
CROSS SECTION ALONG
LINE A-A'
Scale in feet
Fig. 3.
—
Map and Sections of the Engle Cope Mine, Jackson County.
The mica is light rum ; some of it has a light-greenish cast. Much is slightly wavy and soft. A high
proportion contains a light-green mottling, but iron oxide spots are uncommon. Reeves and cracks are
subordinate and "A" structure occurs chiefly in the larger books.
FRADY MINE
D. M. Larrabee
The Frady mine is 3i/
2 miles N.85°W. of Cullowhee, Jackson County, near the top of a northward-facing
ridge.
The mine is said to have been opened about 60 years ago by C. and E. Bowers, of Webster. M. D.
Cowan, the present owner, has operated the mine from October 1942 to the present (October 1944). Devel-opment
consists of a main adit, the Bowers adit, several short adits, stopes, and open cuts, and shafts to a
depth of 135 feet. These workings form a series 650 feet long trending about N.60°W.
Sylva District, North Carolina 37
Three pegmatite bodies are exposed on the property, but nearly all of the mica has been obtained from
one. This main pegmatite is 4 to 8 feet thick and consists of a central core of quartz flanked by narrow
margins of plagioclase, quartz, and muscovite. A few red garnets are present near the contacts. Microcline
is associated with the central quartz masses. The muscovite, which is rum to ruby and slightly stained, is
associated with the contacts rather than with the quartz masses. The mica zones are richest along the foot-wall
contact, where the books are also largest. This zone is richest over a 6-inch width which occasionally
widens to 12 inches. The hanging-wall mica zone is of equal width but is leaner ; the mica therein is smaller
but of darker color and better quality.
The country rock is biotite gneiss with occasional layers of hornblende gneiss. The foliation strikes
northwest and dips steeply northeast. Although the pegmatites generally parallel the foliation, trending
northwest and dipping steeply northeast, they are locally discordant. All rocks have been subjected to much
faulting of apparently small displacement. As a result many of the mica books are badly folded, bent, ruled,
and warped.
IOTLA-BRADLEY MINE
D. M. Larrabee
The Iotla-Bradley mine (also known as the Iotla or Iotla Bridge mine) is 4 airline miles N. 10°W. of
Franklin, Macon County. It lies at an altitude of about 2,000 feet on the west bank of the Little Tennessee
River at the mouth of Iotla Creek. The mine was first operated in 1905 by Francis A. Gudger, who later
leased it to the Southern Mica Company. This company mined it for both kaolin and mica for about 10
years. In 1935 Charles Bradley of Franklin leased the property and operated it as a scrap and sheet mine
until 1940, when the Bradley Mining Company was formed. Bradley relinquished his interest in this com-pany
in 1944 and the present officers are Messrs. Preston, Lee, and Zieseniss of New York City.
The workings consist of a large open-cut which is 800 feet long, averages 200 feet in width, and has a
maximum depth of about 160 feet. (See fig. 4.) Older workings consisted of several shafts and adits, many
of which have been completely destroyed or rendered inaccessible by the open-cut operation.
A large irregular body of pegmatite has been explored over a length of 800 feet and has a maximum ex-posed
width of 200 feet. It trends N. to N.30°E. and is vertical, cutting across the foliation of biotite gneiss.
The walls are extremely irregular, and large septa and inclusions of wall rock are common near the margins
of the mass.
The pegmatite body is poorly zoned and consists of a medium-grained aggregate of kaolinized feldspar,
muscovite, quartz, and a little biotite. Several small auartz pods occur near the south end of the open-cut and
a large quartz rib as much as 120 feet long and 15 feet thick lies near the western contact at the north end
of the main open-cut.
Mica of scrap grade is uniformly distributed throughout the mass of pegmatite, but sheet mica is con-fined
to zones surrounding the large quartz rib. The scrap mica occurs in scattered books and flakes generally
less than 2 inches in diameter, and is of deep-rum color. The mica-rich zones along the quartz rib contain
books as much as 2 feet in diameter. This mica is of deep-rum color, is ruled, and some of it contains "A"
structure.. In general, however, books from this zone are hard and flat and of excellent quality.
The deposit has been operated chiefly for kaolin and scrap mica with by-product sheet mica. The quarry
has been developed by benching with gasoline shovels. The ore is loaded by shovels into trucks and hauled
to a small jaw crusher at the bottom of the main pit, where it is broken and washed into a bucket conveyor
that carries it to the rim of the open-cut. From there the ore goes by flume to the mill, where the stream is
split to feed two similar units. The material passes through two sets of rolls and trommel screens before
reaching the drying bin for draining. It is then put through a wood-fired rotary dryer, and thence passes
to another set of rolls and a trommel screen. Mica to be sold as jigged scrap goes directly to storage bins
for bagging; that which is to be pulverized before sale passes through a Raymond mill.
The production of scrap mica is reported to average 3,000 tons per year. Mica constitutes about 10
percent of the rock moved. Sheet mica production was considerably curtailed after June 1944 because the
sheet mica zones were partly covered by large slides of material from the walls of the cut. Selected mine-run
mica from the mica-rich zones contains about 8 percent of sheet and punch mica.
38 Mica Deposits of the Franklin-
: 3j Biotite gneiss
j Contoct, locotion occurole, showing dip
/ Contoct, location opproximote
Contact between pegmatite units
Attitude of foliotion
Limit of exposure
Rim of open cut
Outline of* underground workings
Margin of dump
50 100
SCALE IN FEET
Fig. 4.
—
Map of the Iotla-Bradley Mine, Macon County.
KISER MINE
E. Wm. Heinrich
The Riser mine is 4 airline miles S.87°W. of Franklin, Macon County, at an altitude of 2,300 feet on the
west side of a small tributary of Mill Creek. The mine is owned by J. Burn Riser of Route 1, Franklin, and
only prospecting was done before 1942. George Scott of Franklin operated the mine from November 19,
1942 to May 8, 1944, at which time A. W. Reid of Franklin secured the lease and continued operations until
late November 1944.
The workings (pi. 11) consist of an open-cut 145 feet long, 65 feet in maximum width, and 35 feet in
maximum depth, and a shallow bulldozer trench to the south. Both the country rock and pegmatite are
decomposed, and large slides from the walls of the cut are common.
Sylva District, North Carolina 39
BULLETIN 49 PLATE 11
C/TOSS SECTION
ALONG LINE A-A'
CONTOUR INTERVAL 5«T
DATUM ASSUMED
Mopped by EWm Heinnch, LC Proy, MR Klepper,
3-1-44 ond 5-2-44. Remopped by R.W Lemke
ond EWm Heinnch 11-16-44
EXPLANATION
Dump (in section)
Quortz-feldspor pegmotile
Sheet mica
Gneiss with injected granitic moterial
Biotite gneiss
Contact, location accurate, showing dip
Contact, location approximate
Attitude of foliation
Limit of exposure
Rim of open cut or trench
Dump
60
SCALE IN FEET
Map and Sections of the Riser Mine, Macon County.
The open-cut exposes a single pegmatite body that strikes N.45°E. and appears to be vertical. The
country rock is a fine-grained biotite gneiss, whose vertical foliation strikes a few degrees north of west. The
pegmatite cuts across the foliation, and the contacts between the two rocks are i