Geology and Resources of 

Fluorine in the United States 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 933 
COVER PHOTOGRAPHS 

1 2 3 4 

5 6 

7 8 

9 10 

11 12 13 14 

1. Asbestos ore 

2. Lead ore, Balmat mine, N. Y. 

3. Chromite-chromium ore, Washington 

4. Zinc ore, Friedensville, Pa. 

5. Banded iron-formation, Palmer, 

Mich. 

6. Ribbon asbestos ore, Quebec, Canada 

7. Manganese ore, banded 

rhodochrosite 

8 . Aluminum ore, baux ite, Georgia 

9. Native copper ore, Keweenawan 

Peninsula, Mich. 

10. Porphyry molybdenum ore, Colorado 

11 . Zinc ore, Edwards , N . Y. 

12. Manganese nodules, ocean floor 

13. Botryoidal fluorite ore, 

Poncha Springs, Colo. 

14. Tungsten ore, North Carolina 
Geology and Resources of 

Fluorine in the United States 

Edited by DANIEL R. SHA WE 

With sections by D. R. SHAWE, R. E. VAN ALSTINE, 

R. G. WORL, A. V. HEYL, R. D. TRACE, R. L. PARKER, 

W. R. GRIFFITTS, C. L. SAINSBURY, and J. B. CATHCART 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 933 

An evaluation of the geochemistry, 

geographic distribution, and 

geologic environments of fluorine, 

and descriptions of major United 

States fluorine mineral deposits 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1976 
UNITED STATES DEPARTMENT OF THE INTERIOR 

THOMAS S. KLEPPE, Secretary 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress catalog-card No. 76-600061 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 

Stock Number 024-001-02901-4 
APPRAISAL OF MINERAL RESOURCES 

Continuing appraisal of the mineral resources of the United States is conducted 

by the U.S. Geological Survey in accordance with the provisions of the Mining 

and Minerals Policy Act of 1970 (Public Law 91-631, Dec. 31, 1970). Total resources 

for purposes of these appraisal estimates include currently minable resources 

(reserves) as well as those resources not yet discovered or not currently profitable 

to mine. 

The mining of mineral deposits, once they are discovered, depends on geologic, 

economic, and technologic factors; however, identification of many deposits yet 

to be discovered, owing to incomplete knowledge of their distribution in the 

Earth's crust, depends greatly on geologic availability and man's ingenuity. Consequently, appraisal of mineral resources results in approximations, subject to 

constant change as known deposits are depleted, new deposits are found, new 

extractive technology and uses are developed, and new geologic knowledge and 

theories indicate new areas favorable for exploration. 

This Professional Paper discusses aspects of the geology of fluorine as a framework for appraising resources of this commodity in the light of today's technology, 

economics, and geologic knowledge. 

Other Geological Survey publications relating to the appraisal of resources of 

specific mineral commodities include the following: 

Professional Paper 820-"United States Mineral Resources" 

Professional Paper 907-"Geology and Resources of Copper Deposits" 

Professional Paper 926-"Geology and Resources of Vanadium Deposits" 

Professional Paper 959-"Geology and Resources of Titanium in the United States" 

CONTENTS 

Page 

Abstract............................................................................................. 1 

Introduction, by R. E. Van Alstine.................................................. 3 

Geochemistry of fluorine, by D. R. Shawe ...................................... 4 

Abundance of fluorine in rocks . .. ..... .. . ........ .. .. ...... .. .... ....... ...... 5 

Abundance of fluorine in gases and waters.............................. 9 

Geochemical cycle of fluorine................................................... 12 

Element associations, by R. E. Van Alstine and D. R. Shawe ........ 14 

Geographic distribution of fluorine in igneous rocks, by 

D. R. Shawe .............. .. ........................................................... 15 

Geologic environments and distribution of fluorine, by 

D. R. Shawe and R. E. Van Alstine...................................... 17 

Fluorine in fluorite deposits and occurrences.......................... 17 

Fluorine in topaz deposits and occurrences.............................. 19 

Fluorine in phosphate and fluorapatite deposits..................... 19 

Fluorine in other deposits......................................................... 19 

Tectonic setting of fluorine deposits, by D. R. Shawe .................... 22 

Relation of fluorine deposits to faults...................................... 22 

Relation of fluorine deposits to intrusive igneous rocks ..... .. .. 25 

Relation of fluorine deposits to geophysical properties........... 27 

Descriptions of major fluorine deposits and districts and 

important types of fluorine occurrences................................ 30 

Alaska, by C. L. Sainsbury ......................................... ·............... 30 

Descriptions of individual districts and deposits .... .. .. ...... 30 

Lost River.................................................................... 30 

Other deposits . .. . .... .. .. . ...... .. .. ......... ... . .... .. .. ....... ... . . ..... 33 

Washington-Idaho-Montana-Wyoming-South Dakota, 

by R. L. Parker................................................................ 34 

Descriptions of individual districts and deposits............... 34 

Washington ................................................................. 34 

Idaho ............................................................................ 35 

Meyers Cove . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 

Bay horse............................................................... 36 

Stanley area .. . .. .. ..... .. .. ..... ... . . . . ....... .. ..... .... .. ...... ... . 36 

Big Squaw Creek.................................................. 37 

Other deposits...................................................... 37 

Montana ...................................................................... 38 

Crystal Mountain................................................. 38 

Snowbird.............................................................. 38 

Spar ....................................................................... 39 

Other deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 39 

Wyoming ..................................................................... 40 

South Dakota............................................................... 41 

Nevada-western Utah-southeastern Oregon-southeastern California-western Arizona, by R. G. Worl and 

W. R. Griffitts............................................................... 41 

Descriptions of individual districts and deposits............... 43 

Nevada ......................................................................... 43 

Broken Hills......................................................... 43 

Quinn Canyon Range.......................................... 44 

Utah ............................................................................. 47 

Spor Mountain..................................................... 47 

Arizona ........................................................................ 47 

Castle Dome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7 

Other deposits...................................................... 48 

Descriptions of major fluorine deposits and districts and 

important types of fluorine occurrences-Continued 

Colorado-New Mexico-western Texas-southeastern 

Arizona, by R. G. Worl, W. R. Griffitts, and R. E. Van 

Page 

Alstine............................................................................. 48 

Descriptions of individual districts and deposits.............. 53 

Colorado...................................................................... 53 

Jamestown............................................................ 53 

Northgate . ... . . .. ....... .. .. ....... .. ......... ... ...... .. ..... .. . ..... 56 

Other deposits...................................................... 58 

New Mexico ........................................................... ~····· 59 

Burro Mountains.................................................. 59 

Gila....................................................................... 59 

Cooks Peak-Fluorite Ridge.................................. 59 

Sierra Cuchillo.. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 

Zuni Mountains .................................................. . 

Sierra Caballos .................................................... . 

Grants .................................................................. . 

Southeastern Arizona ................................................. . 

Duncan ................................................................ . 

Other deposits ..................................................... . 

Central and Eastern United States, by A. V. Heyl and 

R. E. Van Alstine ........................................................... . 

Illinois-Kentucky ............................................................... . 

Illinois-Kentucky fluorspar district, by 

R. D. Trace ...................................................... . 

Geologic setting .................................................. . 

Fluorspar ore deposits ......................................... . 

Summary ............................................................. . 

Central Kentucky ........................................................ . 

Cumberland River, Kentucky .................................... . 

Tennessee-North Carolina-Virginia .................................. . 

Central Tennessee ....................................................... . 

61 

61 

61 

62 

62 

62 

62 

63 

63 

65 

70 

72 

74 

74 

74 

74 

Sweetwater, Tennessee ................................................ 75 

Del Rio, Tennessee-Hot Springs, North Carolina...... 75 

Hamme, North Carolina-Virginia.............................. 76 

Faber, Virginia............................................................ 76 

Other deposits, Virginia.............................................. 76 

Alabama.............................................................................. 77 

Missouri-Arkansas-central Texas ...................................... . 

Southeast Missouri ..................................................... . 

Other deposits, Missouri and Arkansas ..................... . 

Llano uplift, central Texas ........................................ . 

New York ........................................................................... . 

Adirondack Mountains .............................................. . 

Other deposits ............................................................ . 

New England ..................................................................... . 

Cheshire County-Westmoreland, New Hampshire .... . 

North Chatham, New Hampshire ............................. . 

Long Hill (Trumbull)-Monroe, Connecticut.. .......... . 

Long Island, Blue Hill Bay, Maine ........................... . 

Other districts and deposits of the Central and 

77 

77 

77 

77 

78 

78 

78 

79 

79 

79 

79 

79 

Eastern United States................................................ 79 

Fluorine in phosphate deposits, by J. B. Cathcart................... 82 

v 
VI CONTENTS 

Page Page 

Present and future resources of fluorine, by D. R. Shawe, Present and future resources of fluorine-Continued 

R. G. Worl, R. E. Van Alstine, and A. V. Heyl.. .................. 83 Suggestions for likely future fluorine provinces: 

Summary of fluorine resources, by R. E. Van Alstine Speculative fluorine resources, by D. R. Shawe, 

and R. G. Worl. ............................................................... 83 R. G. Worl, and A. V. Heyl ........................................... 86 

Known favorable areas for fluorine exploration, by Geochemical and geophysical prospecting methods for fluorine, 

D. R. Shawe, R. E. Van Alstine, R. G. Worl, by W. R. Griffitts and R. E. Van Alstine .............................. 89 

and A. V. Heyl ................................................................ 85 References .......................................................................................... 91 

ILLUSTRATIONS 

Page 

FIGURES l-5. Graphs: 

I. Fluorine and silica contents of olivine basalt from Kilauea, Hawaii ............... ......................................................... 6 

2. Fluorine and silica contents of five igneous suites..................................................................................................... 6 

3. Fluorine and silica contents of nine igneous suites from the United States.............................................................. 7 

4. Fluorine and silica contents of l:>asalts and andesites from Western United States and Antarctica.......................... 8 

5. Fluorine and silica contents of hybrid granitoid rocks of Jurassic age and aplite of Oligocene age from the 

southern Snake Range, Nevada............................................................................................................................ 9 

6. Map showing distribution of fluoride content of ground water in the United states............................................................. II 

7. Scatter diagram showing relation of fluorine to silica in volcanic rocks................................................................................ 13 

8-17. Maps: 

8. Distribution of fluorine-rich igneous rocks in the United States............................................................................... 16 

9. Distribution of fluorite deposits in the United States.................................................................................................. 18 

10. Locations of major topaz deposits, topaz occurrences, and topaz-bearing rhyolites in the United States................ 20 

II. Locations of phosphate and fluorapatite deposits in the United States.................................................................... 21 

12. Major faults, distribution of fluorine minerals, and major belts of fluorite deposits in the United States.............. 23 

13. Normal faults, and distribution of fluorine mineral deposits in the Western United States.................................... 24 

14. Major Phanerozoic intrusive bodies and distribution of fluorine minerals in the United States............................. 26 

15. Bouguer gravity map and distribution of fluorine mineral deposits in the United States........................................ 28 

16. Fluorite mineral belts and high heat-flow regions in the Western United States and positive aeromagnetic 

anomalies in Colorado.......................................................................................................................................... 29 

17. Crustal thickness, crustal seismic velocity, upper-mantle seismic velocity, and distribution of fluorine mineral 

deposits in the United States................................................................................................................................ 31 

18. Longitudinal projection along "main vein" of the Baxter (Kaiser) fluorspar mine, Broken Hills district, Nevada............ 44 

19-21. Maps: 

19. Locations of fluorspar deposits in the Quinn Canyon Range, Nev........................................................................... 45 

20. Jamestown district, Colorado ... ........................................................................................................ ........................... 54 

21. Fluorspar deposit at the Burlington mine, Jamestown district, Colorado................................................................. 55 

22. Sketch showing slab of fluorspar from Northgate, Colo......................................................................................................... 58 

23. Map showing major structural features, igneous rocks, and distribution of known fluorspar deposits, IllinoisKentucky fluorspar district................................................................................................................................................. 64 

24. Stratigraphic column, Illinois-Kmtucky fluorspar district...................................................................................................... 66 

25. Generalized stratigraphic column, western Kentucky fluorspar district.................................................................................. 67 

26. Map showing major structural features in the region surrounding the Illinois-Kentucky fluorspar district........................ 69 

27. Cross section of Davenport mine, Moore Hill area, Kentucky................................................................................................. 70 

28. Map of Cave in Rock fluorspar district, Hardin County, Ill................................................................................................... 71 
GEOLOGY AND RESOURCES OF FLUORINE IN THE UNITED STATES 

Edited by D. R. SHAWE 

ABSTRACT 

Fluorine mineral resources are evaluated in this report in the perspective of the geochemistry of fluorine and the geologic environment of 

fluorine mineral deposits. Rapidly increasing demand and the possibility of shortages in supply of fluorspar and other fluorine products that 

are vital to the economy of the United States prompted this review of 

fluorine resources. 

Continental crustal abundance of fluorine averages about 650 ppm 

(parts per million); basalts and gabbros average about 400-500 ppm, 

andesites and granodiorites 600 ppm, and rhyolites and granites 800 

ppm; alkalic extrusive and intrusive rocks average much higher, 

900-2,600 ppm. Despite the higher average fluorine content of silicic 

rocks, many silicic rocks contain as little fluorine as do low-fluorine 

mafic rocks. Intrusive rocks tend to contain higher amounts of fluorine 

than do extrusive rocks of similar composition. Metamorphic and sedimentary rocks have average fluorine contents similar to those of igneous 

rocks. Sandstones, carbonate rocks, and evaporites average about 200-250 

ppm F, and oceanic sediments and shales 700-900 ppm. Marine phosphorites contain remarkably more fluorine, averaging more than 30,000 

ppm. Soils average less than 300 ppm F. 

In some comagmatic series of igneous rocks, fluorine increases with 

silica, and has been concentrated by magmatic differentiation. In other 

series fluorine decreases with silica, and the fluorine distribution in the 

rocks appears to have resulted from wallrock contamination. A further 

control of the abundance of fluorine in igneous rocks is the presence or 

absence of minerals that can readily accommodate fluorine in their 

crystal structures, so that hornblende- and biotite-rich rocks may contain 

more fluorine than do more silicic members of the same igneous series. 

Fluorine content is lowest in igneous rocks that have been irrupted 

through oceanic crust and highest in igneous rocks irrupted through 

continental crust. Fluorine appears to be highest in rocks of alkalic 

affinity and these appear to have originated mainly as magmas derived 

from the mantle beneath the continental crust. 

Some volcanic gases and sublimates contain notable amounts of 

fluorine; in general high-fluorine silicic and alkalic magmas exhale 

higher amounts of fluorine than do low-fluorine mafic magmas. 

Expulsion of fluorine from high-fluorine magmas may have occurred 

principally because of pressure drop due to magma rise, 

Surface waters average 0.25 ppm F, and higher contents are found 

mostly in arid regions. Ground waters contain an average of 0.4 ppm F. 

Pacific and Atlantic sea waters contain about 1.2 ppm F. Connate and 

related waters average 2. 7 ppm F, and thermal waters associated with 

volcanoes and epithermal mineral deposits average 5.4 ppm F. 

Most of the fluorine transported to the sea is carried in minerals held in 

suspension and deposited in detrital sedimentary rocks. Only rarely do 

conditions develop where fluorine is deposited chemically in marine 

phosphorite deposits. 

Fluorine shows a strong geochemical affinity for the assemblage of 

elements bery llium-lithi urn -manganese-niobium -tin-tungsten-uraniurn-yttrium-lead-zinc and is commonly found with these elements in a 

wide variety of geologic environments. 

High-fluorine igneous rocks are geographically restricted to two 

major provinces in the United States, one a broad belt extending from 

southern Maine southwestward into Alabama and the other aU-shaped 

region extending from southwestern Montana southward into southern 

California, eastward to southwestern New Mexico, and northward 

through western Colorado. Fluorine-rich igneous rocks in the Eastern 

United States are dominantly Paleozoic in age and those in the Western 

United States are dominantly Tertiary in age. 

Fluorine mineral deposits occur in a wide variety of geologic environments and in a multitude of forms. Veins, mantas, pipelike bodies, 

breccia stockworks, contact zones, pegmatites, greisens, disseminated 

deposits, and bedded layers occur variously associated with or enclosed 

within volcanic rocks, intrusive igneous rocks, metamorphic rocks, or 

sedimentary rocks. Fluorite is the most common and abundant fluorine 

mineral, and fluorspar constitutes the ore of fluorite. Other significant 

fluorine minerals that likely constitute future resources are topaz, fluorapatite, and the carbonate-apatite of sedimentary phosphate rock. 

Additional minerals that may become economically significant sources 

of fluorine are cryolite, sellaite, villiaumite, bastnaesite, and the humite 

group of silicates. 

Fluorine occurs in epigenetic mineral deposits principally in broad 

provinces in the Eastern and Western United States that coincide closely 

with the broad provinces of fluorine-rich igneous rocks. On the basis of 

available age data the deposits also are similar in age to associated 

igneous rocks. Fluorine is found in marine phosphate rocks chiefly in the 

Southeastern and the Western United States. 

Distribution of epigenetic fluorine mineral deposits in the United 

States has been strongly controlled by tectonic environment. There is a 

close spatial association of fluorine mineral deposits with major fault 

zones. In the Western United States the distribution of Tertiary fluorine 

mineral deposits closely follows the distribution of Basin-Range 

structure; some deposits occur in tensional faults. The distribution of 

fluorine mineral deposits in northwesterly, northeasterly, and easterly 

belts suggests an association with deep-seated strike-slip fault zones of 

these orientations that seem to constitute a fundamental structural 

framework of the continental crust. 

Regions of low gravity in the United States that broadly represent 

crustal zones intruded by significant volumes of silicic igneous rocks 

correlate in a rough way with regions of fluorine mineral deposits. 

Regions of high heat flow in the Western United States that reflect the 

middle Tertiary to present episode of magmatic and hydrothermal 

activity of this part of the country coincide remarkably with the regions 

of rather young fluorine mineral deposits. Available regional aeromagnetic data reveal that zones of numerous sharp positive anomalies (that 

represent in part intrusive igneous centers) coincide with the positions of 

fluorine mineral belts. 

A broad region of low seismic velocity in the upper mantle in the 

Western United States closely encompasses the region of middle to late 

Tertiary magmatism and fluorine mineralization. Inferences on the 

composition of the low velocity upper-mantle material suggest that 
2 GEOLOGY AND RESOURCES OF FLUORINE 

volatile components composing fluorine-enriched magmas were 

fractionated out of the upper mantle and injected into the crust which 

accounts for the higher heat flow, the fluorine-rich igneous rocks, and 

the fluorine mineral deposits of the province. Plate tectonics is invoked 

to account for extension of the continental crustal plate beginning in 

middle Tertiary time; this extension was accompanied by conjugate 

strike-slip faulting in the lower part of the crust and tensional faulting in 

the upper part of the crust. Crustal extension resulted in a phase transformation in the upper mantle, which accounts for the development of 

fluorine-rich magmas that were injected upward into the crust and were 

accompanied by fluorine mineralization. 

Fluorine mineral deposits that have had significant production or 

constitute a significant type are described in the text on the basis of 

geographic distribution and geologic environment. In the Lost River tin 

district, Seward Peninsula, Alaska, large carbonate-replacement and 

pipelike fluorspar deposits are associated with granitic intrusives. Elsewhere on the Seward Peninsula, fluorite occurs in other tin districts, in 

mineralized carbonate rocks north of Nome, in breccia pipes in the 

Kigluaik Mountains, and in carbonate rocks surrounding alkalic 

intrusives in the Darby Mountains. In other parts of Alaska, fluorite and 

topaz are associated with peralkalic granites and occur in some sulfide 

deposits. Large fluorine resources are known but currently inaccessible 

in marine phosphate rock in northern Alaska. 

In the northwestern part of the United States, important fluorsparproducing areas are the Meyers Cove and Challis deposits, Idaho, where 

fluorite veins occur in volcanics and porphyries and in dolomite, 

respectively; and the Snowbird, Spar, and Crystal Mountain deposits, 

Montana, which are pegmatitelike bodies. Numerous other fluorspar 

deposits associated with volcanic rocks, granitic intrusive rocks, or 

alkalic rocks, or occurring as pegmatites or disseminated in granite are 

widespread in north-central Washington, central and southwestern 

Idaho, western to central Montana, several areas in Wyoming, and the 

Black Hills of South Dakota. 

In the southwestern part of the United States manto replacement and 

pipelike bodies of fluorspar occur in limestone in the Fluorine district, 

Nevada; vein deposits are found in andesite and rhyolite at Broken Hills, 

Nev.; pipe deposits are known in carbonate rocks at Spor Mountain, 

Utah; and veins occur in volcanic rocks in the Indian Peak Range, Utah. 

Throughout much of Nevada, southeastern California, western Utah, 

and western Arizona numerous occurrences of fluorspar are known in 

veins, mantos, or pipelike bodies in and associated with volcanic rocks, 

in contact zones or stockworks of hypabyssal or plutonic igneous rocks, 

in volcaniclastic sediments, and in pegmatites. The Quinn Canyon 

Range district, the Wells Cargo deposit, and the Iowa Canyon deposits, 

Nevada, and the Castle Dome district, Arizona, offer promise of 

substantial fluorspar production. 

The southern Rocky Mountain region of the Western United States in 

Colorado, New Mexico, western Texas, and southeastern Arizona contains numerous fluorspar deposits. Many deposits are characterized as 

layered or crustified veins in young steep tensional faults or breccia zones 

occurring in Tertiary volcanic rocks, Paleozoic or Mesozoic sedimentary 

rocks, or Precambrian silicic igneous or metamorphic rocks. Such veins 

are in the Northgate and Browns Canyon districts, and near Crystal, 

Dillon, Poncha Springs, and Wagon Wheel Gap, Colo., and the Gila, 

Burro Mountains, Anderson, Gold Hills, Steeple Rock, Sierra Caballos, 

Zuni Mountains, Fluorite Ridge, and Cooks Peak districts, and deposits 

at Tonuco, Tortugas Mountain, Bishop Cap, and Sierra Cuchillo, N. 

Mex. Manto deposits occur in carbonate rocks in the Sierra Caballos and 

Sierra Cuchillo, and at Tortugas and Bishop Cap deposits, New Mexico, 

and in the Eagle Mountains and Christmas Mountains-Corazones Peak 

districts in Texas. At the Jamestown district, Colorado, significant stockworks, pipelike shoots, and mineralized breccia zones, containing fluorite and lead, silver, gold, and uranium minerals, occur in Precambrian 

granite near a middle Tertiary alkalic-silicic stock. 

In the Illinois-Kentucky district, large and numerous veins and replacement bodies of fluorspar, barite, and sphalerite occur in faulted 

carbonate rocks in the v1cm1ty of small mafic-alkalic dikes. These 

deposits have yielded more than 75 percent of the fluorspar mined in the 

United States. Large low-grade tonnages of fluorspar-mineralized 

breccia are known in the vicinity of Hicks dome, Illinois, but have not yet 

been developed. 

In the Central and Eastern United States outside of the IllinoisKentucky district, numerous fluorine mineral deposits are known and 

some offer promise of substantial fluorine resources. High-temperature 

veins, lodes, greisens, tactites, and skarns commonly containing fluorite 

and topaz and associated minerals of tungsten, tin, silver, gold, lead, zinc, 

molybdenum, iron, rare earths, and thorium, occur in the Appalachian 

structural belt, the Ozark dome, Missouri, and the Llano uplift, Texas. 

Intermediate-temperature deposits are chiefly veins such as fluoritequartz veins in the Cheshire County-Westmoreland district, New Hampshire, and complex fluorite-bearing veins near Faber, Va.; in the 

Connecticut Valley, Mass.; near Phoenixville, Pa.; on Deer Isle, Maine; 

and at Litchfield, Conn. 

Most of the fluorspar deposits in the Central and Eastern United States 

are low-temperature veins, mantos, breccia bodies, stockworks, pipelike 

bodies, and disseminated deposits. The largest and most numerous 

deposits outside of the Illinois-Kentucky field, are in the Mississippi 

Valley and in the Appalachian Valley and Ridge province in the vicinity 

of related zinc deposits. Other Mississippi Valley-type districts are the 

Central Tennessee district, the Cumberland River district, the Central 

Kentucky district, and the Rossie area, New York. Deposits of the Valley 

and Ridge type are numerous along the Appalachian belt from Alabama 

into Pennsylvania in Cambrian-Ordoviciancarbonaterocks. The largest 

deposit is in the Sweetwater district in eastern Tennessee. Others are the 

Del Rio, Tenn., and Hot Springs, N.C., districts and the Gilley deposit 

in northeastern Alabama. Disseminated deposits are found in central 

Pennsylvania, northeastern New York, northeastern Iowa, northwestern Ohio, and southeastern Ohio. 

Residual deposits of fluorspar are known in western Kentucky, central 

Kentucky, and central Tennessee, and placer deposits of topaz are known 

in South Carolina and in the Llano uplift of central Texas. 

Economic fluorine-bearing phosphate deposits in the United States 

are confined to marine sedimentary phosphorites of Ordovician age in 

Tennessee, of Permian age in Idaho, Montana, Wyoming, and Utah, of 

Miocene age in North Carolina, Georgia, and South Carolina, and of 

Miocene and Pliocene ages in Florida. Fluorine content of the rock is 

about 3-4 percent, and billions of tons of phosphate resources are known. 

Present and future resources of fluorine in the United States are 

evaluated in the light of past production. In the past most fluorine 

production has come from fluorspar, and fluorspar will continue to be 

the major source in the near future. Phosphate rock and other byproduct 

and coproduct sources will become increasingly important as fluorspar 

resources diminish. From 1900 to about 1950 the United States changed 

from a minor producer of fluorspar to the major world producer, but 

from 1950 to 1970 has reverted to the seventh or eighth leading producer. 

Production generally has risen in recent years, however, until it now 

averages about 200,000 short tons CaF2 annually. Until about 1950 

United States production of fluorspar nearly equaled its consumption, 

but since 1950 consumption has increased dramatically to nearly 

1,500,000 short tons of CaF2 annually. In addition, since 1950worldwide 

fluorspar consumption has increased spectacularly to more than 

4,500,000 short tons of CaF2 annually, emphasizing the fact that the 

United States is faced with strong competition for foreign supplies of 

fluorspar. 

United States reserves of fluorspar are about 25,000,000 short tons of 

crude ore ( > 35 percent CaF2). Hypothetical resources of fluorspar in the 

United States are about 45,000,000 short tons. 

The marine phosphate rock deposits of Florida, North Carolina, 

Tennessee, Utah, Wyoming, Idaho, and Montana contain about onethird billion tons of fluorine in known reserves and about 2 billion tons 

of fluorine in identified resources. Marine phosphate rock thus constitutes by far the United States' and the world's largest fluorine resource. 
INTRODUCTION 3 

Topaz reserves at the Brewer mine, South Carolina, are about 100,000 

tons of schist averaging about 15 percent topaz; hypothetical resources 

are estimated at about 800,000 tons of rock. In the Front Range, Colo., a 

lens in Precambrian gneiss contains about 15 percent topaz and a reserve 

of about 600,000 tons of topaz-bearing rock. Byproduct resources of topaz 

and fluorite in molybdenum porphyry deposits at Climax and Henderson, Colo., and Questa, N.Mex., may constitute several million tons of 

fluorine. 

Bastnaesite in carbonatite at Mountain Pass, Calif., contains an estimated I ,000,000 tons of fluorine and is a potential byproduct of rare-earth 

extraction. 

Fluorine resources in the United States appear to be adequate for projected needs for many years into the future. Adequate sources of fluorspar are available for the present and near future; vast amounts of 

fluorine in marine sedimentary phosphate deposits are available as a 

more distant future resource, dependent on technological improvements 

in recovery. 

Most fluorine mineral districts and localities in the United States 

remain as areas favorable for further exploration for fluorine resources. 

In productive districts extensions of known fluorspar bodies should be 

sought along strike and in depth, and additional ore bodies may be found 

along nearby faults. Carbonate rocks susceptible to replacement by 

fluorite should be explored, as deposits in such rocks tend to be large and 

amenable to large-scale low-cost mining. An increasingly important 

source of fluorspar will be as a coproduct from the mining of iron, basemetal, barite, and rare-earth ores. 

More analyses for fluorine in earth materials should be made routinely 

to provide background and geochemical information as well as possibly 

to disclose new environments of fluorine mineral deposits. 

Exploration for and evaluation of speculative fluorine 

resources-those occurring in districts and environments yet to be 

identified-must be based on knowledge of the geologic environment 

and the geochemical cycle of fluorine. Geologic mapping in areas not 

now adequately covered by geologic maps will be essential to evaluation 

of geologic environment and to successful exploration in such areas. 

Major geologic parameters that partly define the geologic environment 

of fluorine mineral deposits in western North America are: ( 1) 

extensional tectonism related to deep-seated, mainly northwesterly, 

northeasterly, and easterly strike-slip structures; (2) high heat flow from 

the mantle; and (3) magmatism of alkalic affinity characterized by 

fluorine abundance. These parameters define environments and 

processes in which fluorine was intrinsically available in abnormal 

amounts in some part of the system, and could be mobilized into 

economic concentrations. On the other hand, geologic processes in other 

environments have concentrated minor (crustal abundance) amounts of 

fluorine into deposits of economic interest, such as marine phosphate 

rocks. Earlier concentrations of fluorine may have been dispersed, or remobilized and reconcentrated in new environments by later processes. 

In the Central and Eastern United States new districts of fluorspar in 

carbonate rocks may be found near Toledo, Ohio, near Serpent Mound, 

Ohio, in southern Indiana, in and near the Ste. Genevieve fault zone in 

southeastern Missouri and southern Illinois, along the Cumberland 

River, Ky., in central Tennessee and central Kentucky, and near Magnet 

Cove, Ark. 

In the Western United States fluorspar deposits undoubtedly underlie 

parts of the widespread cover of Tertiary and Quaternary sediments and 

volcanics. Fluorite-bearing Cenozoic tuffaceous lake beds and other 

similar deposits in the Western United States may offer potential for large 

fluorine resources. Fluorspar deposits related to silicic-alkalic volcanic 

rocks in the Western United States may be found in the igneous areas of 

the Big Bend region of Texas, Nacimiento region of Arizona, New 

Mexico, and Colorado, and the Shoshone province of Nevada, Utah, 

Idaho, Wyoming, and Montana, particularly southeastern Idaho, northwestern Wyoming, and northwestern Utah. Caldera ring-fracture zones 

in addition to major deep-seated strike-slip fracture zones and major rift 

structures may be favorable for undiscovered fluorspar districts in these 

regions. Deposits of syngenetic fluorite associated with marine gypsum 

and limestone of Permian age, like the deposits in north-central 

Wyoming, may be found elsewhere in the United States. 

Large deposits of carbonate-fluorapatite in marine phosphate rock 

probably exist beneath the sea in Cenozoic coastal plain sediments 

extending east from the deposits in the Carolinas and Florida. Fluorine 

may be recoverable from deposits of fluorapatite in alkalic rocks and 

from deposits of fluorapatite and magnetite forming contactmetamorphic zones around intrusives. 

Probably millions of tons of topaz-bearing rock are yet to be discovered 

in widespread metamorphic terranes throughout the United States, as 

well as in presently unknown molybdenum porphyry deposits. 

Inasmuch as cryolite for many years constituted a significant fluorine 

resource at Ivigtut, Greenland, it conceivably may occur in similar 

deposits elsewhere. Sodium fluoride in saline lake beds may some day be 

a source of fluorine. Many other very low-grade geologic sources of 

fluorine offer potential only for the distant future. 

Some very large low-grade multicommodity ores, in which fluorine 

minerals are associated with metallic minerals, barite, rare-earth 

minerals, apatite, zeolites, feldspars and other minerals of commercial 

value, may become resources of fluorine. 

Geochemical and geophysical prospecting methods may be valuable 

additional aids to apply to exploration for fluorine mineral resources. 

Geochemical techniques as well as panning are useful for detecting 

detrital fluorite that has been dispersed, in some cases as much as 35 

miles, from its source. Some pathfinder elements such as zinc, silver, 

antimony, cadmium, gallium, germanium, vanadium, and molybdenum may be useful in geochemical prospecting for fluorine mineral 

deposits. Uranium identified by radiation detectors might also be a 

useful guide to fluorspar-uranium deposits. Fluorine anomalies rriay be 

guides to deposits of associated valuable minerals. 

An induced activity method of measuring the short-lived isotope f2° 

after activation by a polonium-beryllium source offers promise of 

accurate in-hole measurement of fluorine content of rocks. 

Earth-resistivity, refraction seismic, and self-potential geophysical 

methods have been used to detect structures that may contain fluorine 

mineral deposits. Induced potential methods may successfully outline 

alteration zones that are favorable for fluorine mineral deposits. 

INTRODUCTION 

By R. E. VAN ALSTINE 

Fluorspar, the primary source of fluorine, is a vital and 

integral part of our economy, for it has great commercial 

and strategic importance because of its wide use in the 

metallurgical, chemical, and ceramic industries. Reviews 

(Industrial Minerals, June and July 1970) of the world's 

supplies of fluorspar predict shortages in the near future. 

The increased demand is chiefly the result of the changeover by the steel industry to the basic oxygen process 

requiring about three times as much fluorspar as conventional processes; continued expansion of the aluminum 

industry; and the growing market for fluorine chemicals, 

especially fluorocarbons (MacMillan, 1970). The expanding needs of these industries stimulated review of our 

fluorine resources. 

This report is part of an effort by the U.S. Geological 

Survey to present comprehensive and updated information on the significant mineral resources of the United 

States, with appropriate reference to world resources. The 

expanding industrial needs for fluorine stimulated the 

present review of our resources. Particular attention is 
4 GEOLOGY AND RESOURCES OF FLUORINE 

given to the geochemistry of fluorine, for it defines and 

limits fluorine's geologic environment, and thus the 

origin, habit, and distribution of fluorine mineral 

deposits. Representative examples of the major types of 

deposits (fluorspar, calcium fluophosphate, topaz) and of 

other fluorine-bearing minerals are described in detail, by 

geographic area; many other deposits are described briefly, 

and references to sources of detailed information are given. 

In addition to this report, fluorine resources are also 

reported on briefly by Worl, Van Alstine, and Shawe 

(1973), and a map by Worl, Van Alstine, and Heyl (1974) 

shows distribution of fluorite in the United States. The 

map was intended as a supplement to the present report, 

and reference to it will be made in the following pages. 

Continuing supplies of domestic and imported fluorspar are required to produce the variety of metals and 

materials essential to our industries (Bradbury and others, 

1968, p. 35-60; Williamson, 1961). The United States consumption of fluorspar has doubled in the past decade and 

is expected to grow about 5 percent per year. About 80 

percent of the fluorspar that we consume is imported, 

chiefly from Mexico, Spain, and Italy; fluorspar imports 

exceeded 1 million short tons for the first time in 1968. 

About 80 percentofourdomestic fluorspar, totaling about 

237,000 short tons in 1972, comes from the IllinoisKentucky district, which has been the world's most 

productive district. Small quantities of fluorine compounds are produced as byproducts from the phosphate 

industry, and some fluorine is recovered by the aluminum 

industry from the waste streams of the Hall cell and by the 

chemical industry in plants producing hydrofluoric acid. 

These secondary sources of fluorine should provide for an 

increasing part of the fluorine supply as we become more 

concerned with reducing environmental pollution. 

Although fluorspar is still the primary source of fluorine, 

much more fluorine is lost in phosphate rock that has been 

mined than is recovered from fluorspar. 

The National Materials Advisory Board (NMAB-269, 

1970) estimated that annual consumption of fluorspar in 

the United States would increase by about one-fourth 

between 1970 and 1975, but by only one-fifth between 1975 

and 1980. 

As shown in the accompanying table, production of 

steel and hydrogen fluoride accounts for about 93 percent 

of the total domestic fluorspar consumption. This percentage is not expected to change greatly in the near 

Consumption of fluorspar in the United States, in short tons 

Use 1970 1975 1980 

(estimated) (estimated) 

Steel production .............................. 548,700 723,000 895,000 

Hydrogen fluoride production ....... 726,500 920,000 1,160,000 

Glass and enamels .......................... 35,000 35,000 35,000 

Foundry ........................................... 21,400 24,100 27,400 

All other .......................................... 35,000 45,000 56,000 

Total ..................................... 1,366,600 1,747,100 2,173,400 

future, even though the requirements for the various uses 

are growing. In 1952 the President's Materials Policy 

Commission (Paley, 1952) predicted that the United States 

fluorspar consumption by 1975 would be 1.15 million 

short tons, a quantity that we have exceeded since 1968; 

this prediction is an example of the tendency to underestimate future resource needs. 

In the United States about 3 tons of crude fluorspar is 

mined and beneficiated for each ton of finished product 

marketed. Fluorspar generally is sold in three grades 

-acid, ceramic, and metallurgical. 

Acid-grade fluorspar should contain at least 97 percent 

CaF 2• Limitations are sometimes put on Si02, CaC03, and 

sulfide sulfur. Chemical and physical requirements are 

given in National Stockpile Material Purchase Specifications P-69a-R1, June 1, 1967, General Services Administration. 

Ceramic-grade fluorspar varies substantially with 

individual buyers but is usually finely ground and has a 

CaF2-content ranging from 85 to 97 percent. The Fe20 3-

content usually is limited. 

Metallurgical-grade fluorspar in the form of gravel, 

lump, artificial pellets, or fine flotation concentrates 

contains at least 60 percent effective CaF2 units, determined by subtracting from the contained CaF 2 2.5 percent 

for every percent of Si02 present in the complete analysis. 

National Stockpile Purchase Specification P-69b-Rl, 

December 2, 1963, contains requirements for 

metallurgical-grade fluorspar. 

Published prices ( 1973) per short ton were $78.50-$87.00 

for acid-grade fluorspar, $77-$87 for ceramic-grade, and 

$68.50 for metallurgical-grade pellets (70 percent effective 

CaF 2). The ( 1973) tariff on fluorspar containing more than 

97 percent CaF2 was $1.875 per short ton and was $7.50 per 

short ton on fluorspar containing less than 97 percent 

CaF 2• CaF 2 percentages in this report are weight 

percentages. 

In 1971 ~bout 52 percent of the fluorspar consumed in 

the United States was acid grade, 43 percent was metallurgical grade, and 5 percent was ceramic grade (U.S. Bur. 

Mines, 1973 ). About 97 percent of the quantity consumed 

in 1968 was used in the following 15 States: California, 

Colorado, Delaware, Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan, New Jersey, New York, Ohio, 

Pennsylvania, Texas, and West Virginia (U.S. Bur. Mines, 

1969). 

GEOCHEMISTRY OF FLUORINE 

By D. R. SHAWE 

Fluorine has the atomic number 9, atomic weight 19.00 

(lightest element of Group VII of the periodic table), and a 

valence of minus one in all naturally occurring compounds. It has no isotopes. 

Having an ionic radius of 1.36A, the fluoride ion is 

"readily isomorphous with the hydroxyl ion, (OH)-1 
GEOCHEMISTRY OF FLUORINE 5 

(radius 1.40A), a fact of great importance in its geochemical occurrence and behavior. To a lesser degree, 

fluoride ion may isomorphously replace chloride ion, cl-1 

(radius 1.81A), and oxygen ion, 0-2 (radius 1.40A)." 

(Fleischer and Robinson, 1963, p. 58). 

Fluorine commonly is considered to be concentrated as a 

result of magmatic differentiation into silicic igneous 

fractions, residual solutions, and vapors (for example, 

Fleischer and Robinson, 1963); however, data compiled 

here suggest ambiguity in this conclusion. Although 

certain rhyolitic and granitic rocks, as well as most alkalic 

rocks, contain unusually high amounts of fluorine, some 

consanguineous suites of igneous rocks show higher 

fluorine contents in less silicic members, and alkalic suites 

do not necessarily contain greatest fluorine concentrations in their most differentiated rocks. Further, some 

hybrid granitoid rocks whose chemical character was 

strongly controlled by assimilation of wallrocks show a 

clear decrease in fluorine content with increasing silica 

content. 

ABUNDANCE OF FLUORINE IN ROCKS 

Averages of the fluorine contents of various igneous 

rocks are as follows: 

Rock type 

Extrusive: 

Basalt. ...................................... . 

Andesite ................................... . Rhyolite .................................. . Phonolite ................................ . Intrusive: 

Gabbro .................................... . Granite,2 granodiorite ............. . 

Alkalic rocks ........................... . 

Fluorine, in parts per million 

(number of samples in parentheses) 

Fleischer and Robinson 

( 1963, tables I, II) 

380 (268) 

220 (83) 

700 (145) 

930 (14) 

430 (47) 

840 (183) 

960 (71) 

This report1 

510 (187) 

630 (85) 

780 (261) 

32,640 (100) 

1

Average fluorine contents of igneous rocks compiled for this report include published data and many unpublished data in the U.S. Geological Survey files that are not specifically credited here. 2Fuge and Power (1969) reported a mean fluorine content of 1,395 ppm for 90 unaltered granites from southwest England. _ 5

Gerasimovskiy and Savinova (1969) confirm the higher values for alkalic rocks given here. 

Fleischer and Robinson (1963, p. 61), in noting that 

fluorine appeared to increase with increasing silica 

content of igneous rocks, commented on the unexpectedly 

low fluorine content of andesites and suggested a possible 

regional effect owing to the preponderance of Japanese 

andesites in their summary. A more detailed view of the 

data in the foregoing table, as presented in the next table, 

may clarify this and other discrepancies in the averages for 

certain rock types. 

In all instances the discrepancy between data compiled 

by Fleischer and Robinson and data compiled in this 

report can be attributed to the inclusion of rocks of alkalic 

affinities in the groups with higher fluorine averages. For 

example, rocks such as alkali basalts at Craters of the 

Moon, Idaho, and basalts termed absarokites from the 

Mogollon Rim, Ariz., raise the average fluorine content of 

Rock type 

Basalt: 

Aleutian Islands ..................... .. Hawaii .................................... . 

Snake River Plain ................... . Columbia River Plateau ......... . 

Puerto Rico ............................. . Other ....................................... . Andesite: 

Japan (dominantly) ................ . Aleutian Islands ...................... . Other ....................................... . Rhyolite: 

Alkali rhyolite ......................... . Other ....................................... . Alkalic rock (mostly intrusive): 

Syenite, nepheline syenite 

(dominantly) ........................ . 

Rapakivi granite, mafic alkalic 

rock (dominantly) ............... . 

Fluorine, in parts per million 

(number of samples in parentheses) 

Fleischer and Robinson 

(1963, tables I, II) 

340 (80) 

500 (58) 

210 (77) 

700 (145) 

960 (71) 

This report1 

290 (13) 

320 (71) 

400 (26) 

440 (20) 

460 (5) 

920 (52) 

250 (12) 

2700 (73) 

32,180 (25) 

630 (236) 

2,640 (100) 

1Compilation includes most of the rocks analyzed by the U.S. Geological Survey that were averaged by Fleischer and Robinson, plus additional ones, and also some data reported in the literature but not summarized by Fleischer and Robinson. 2Includes latite and trachyte in silica range 55-65 percent. 5Idaho, Wyoming, Nevada, Utah, Arirona, New Mexico. 

"other" basalts shown under "This report" in the 

preceding table. In contrast, basalts from Iceland have an 

extremely low fluorine content (180 ppm, average of 5; 

Barth, 1947). Although andesites from the Aleutian 

Islands and Japan have similar fluorine contents of about 

200-250 ppm, the average content for the group of "other" 

andesites compiled for this report is appreciably higher 

because more alkalic types (latites and trachytes) that have 

the same silica range as andesite were included. In 

Fleischer and Robinson's compilation of data on alkalic 

rocks, syenites and nepheline syenites dominate, whereas 

in the compilation for this report the alkalic rocks are 

chiefly rapakivi-type granites and mafic alkalic rocks that 

appear to contain significantly more fluorine than do 

syenites. Virtually no duplication is involved in the two 

compilations in this case. 

Fluorine tends to increase with silica in glassy volcanic 

rocks (Shawe and Bernold, 1966, pl. 5-C). Those data are 

summarized in the following table: 

Fluorine content of glassy volcanic rocks 

Silica range 

7 5-80 percent. ................................. . 70-75 ............................................... . 65-70 ............................................... . 

45-65 ............................................... . 

Fluorine, in parts per million 

(number of samples in parentheses) 

1,040 (88) 

670 (49) 

580 (13) 

340 (7) 

Some workers (for example, Coats and others, 1963, p. 

963) have considered that volcanic glasses, having been 

cooled quickly, closely reflect original magma 

composition. If so, the previous table strongly indicates 

that fluorine is concentrated in later fractions by magmatic differentiation. 

Virtual proof of the concentration of fluorine in igneous 

rocks by magmatic differentiation is afforded by the data 
6 GEOLOGY AND RESOURCES OF FLUORINE 

of Wright (1971) and Wright and Fiske (1971). Twentynine olivine basalts from the summit of Kilauea, Hawaii, 

that are considered to be undifferentiated, range from 47.9 

to 51.6 percent silica and contain an average of 410 ppm F 

(Wright, 1971, table 4). Nine other basalts from Kilauea 

classified as having formed by differentiation from magma 

chemically similar to basalts of the summit of Kilauea, on 

the basis of their general chemistry and geologic 

occurrence, range from 51.5 to 55.4 percent silica and 

contain an average of 660 ppm F (Wright and Fiske, 1971, 

table 13). Also, nine samples of "differentiates" -gash 

fracture fillings in natural flows, or material that flowed 

into open drill holes in flow crusts ("oozes")-that range 

from 49.6 to 56.2 percent silica contain an average of 820 

ppm F (Wright and Fiske, 1971, app. 3, table 1). These data 

are presented graphically in figure I. 

Certain other suites of igneous rocks from various parts 

of the world also exhibit a tendency for fluorine to 

increase along with silica, suggesting concentration by 

magmatic differentiation (fig. 2). Of the examples shown, 

however, rocks of the Hallett volcanic province, Antarctica, were considered by Hamilton (1972, p. 59) to 

represent two divergent petrologic series, and rocks from 

the Egan Range, Nev., constitute two groups (one high in 

fluorine, one low), believed by Shawe (1961, p. Bl8l) not to 

be closely related genetically. 

60 

1-

~55 

() 

a: 

w 

a.. 

z 

~ 

0 Ci5 50 

1-

z 

w 

() 60 a: 

w 

a.. 

~ 

500 1 000 1500 2000 2500 

FLUORINE, IN PARTS PER MILLION 

EXPLANATION 

Egan Range, Nevada (Shawe, 1961, 

table 1) 

• Mountain City-Owyhee, Nevada 

(R.R.Coat~unpub.da~J 

x Schell Creek Range, Nevada (Drewes, 

1967, tables 10, 11, 12) 

® Hallett volcanic province, Antarctica 

(Hamilton, 1972, tables 2, 3) 

t:> Black Hills, South Dakota (Norton, 

1970, table 2) 

3000 

500 1 000 1 500 

FLUORINE, IN PARTS PER MILLION 

2000 FIGURE 2.-Positive correlation between fluorine and silica contents 

of five igneous suites. 

EXPLANATION 

• Olivine basalt, Kilauea Summit 

(Wright, 1971, table 4) 

+ Differentiated lavas, Kilauea (Wright 

and Fiske, 1971, table 13) 

x Kilauea ''differentiates" (Wright and 

Fiske, 1971, appendix 3, table 1) 

FIGURE I.-Positive correlation between Horine and silica contents 

of olivine basalt from Kilauea Summit, differentiated lavas of 

Kilauea, and Kilauea "differentiates," Hawaii. 

In comparisons of fluorine content with beryllium content (and indirectly with silica content) of volcanic rocks, 

Griffitts and Powers (1963, p. Bl8-Bl9) and Shawe and 

Bemold ( 1966, p. CB) suggested that positive correlations 

were poor within a group of genetically related rocks, but 

relatively good overall among samples from many 

populations (that is, genetically unrelated rocks). 

Other data, presented by Shawe and Bemold (1966, pl. 

5-A), surprisingly show a negative correlation between 
GEOCHEMISTRY OF FLUORINE 7 

fluorine and silica contents of volcanic tuffs, as summarized in the following table: 

Fluorine content of volcanic tuffs 

Silica range 

75-80 percent. ................................. . 70-75 ............................................... . 

65-70 ............................................... . 

60-65 ............................................... . 

Fluorine, average in parts per million 

(number of samples in parentheses) 

420 (20) 

700 (24) 

700 (22) 

900 (5) 

Most of the tuffs summarized in the above table are 

from the Nevada Test Site, southern Nevada, and the table 

thus generally represents a single igneous petrographic 

province. Many of the tuffs are zeolitized, but it is not 

known if zeolitization had any effect on fluorine content 

of the rocks. 

Other examples of inverse silica-fluorine relations 

among rocks in consanguineous series are illustrated in 

figure 3. Not every example here necessarily represents a 

comagmatic series, but each example does represent a suite 

of igneous rocks generated in a unique segment of the 

crust or upper mantle, a fact reflected by the coherency of 

the field for each example shown. A special case is 

presented by the field for rocks from the Valley of Ten 

Thousand Smokes, Alaska (Lovering, 1957, table 1), in 

fugure 3; most samples are hydrothermally altered ash and 

thus the negative fluorine-silica correlation here is not 

directly attributable to magmatic processes. 

An inverse silica-fluorine relation is shown in yet 

another assemblage of volcanic rocks. Basalts and andesites-excluding basalts from the Aleutian Islands, 

Hawaii, the Snake River Plain, Idaho, the Columbia River 

Plateau, Wash., and Puerto Rico, which plot in restricted 

fields lying mostly between 45-55 percent silica and 

I 00-600 ppm F-are shown in a much broader field in 

figure 4. The strong te11dency for higher fluorine to correlate with lower silica is summarized as follows: 

Fluorine content of basalts from the Western United States and Antarctica 

Silica range 

60-65 percent. ................................. . 55-60 ............................................... . 

50-55 ............................................... . 

45-50 ............................................... . 

40-45 ............................................... . 

35-40 ............................................... . 

Fluorine, average in parts per million 

(number of samples in parentheses) 

100 (1) 

510 (13) 

860 (8) 

1,110 (17) 

1,040 (13) 

1,900 (1) 

Lee and Van Loenen (1971) have shown convincingly 

that the composition of hybrid Jurassic granitoid rocks in 

the southern Snake Range, Nev., was closely controlled by 

the composition of assimilated wallrocks. This suite of 

related igneous rocks whose compositions vary serially 

and hence suggest origin through magmatic differentiation are thus shown to have developed probably simul1-

z 

w 

~55 

w 

0.. 

2000 2500 3000 3500 

FLUORINE, IN PARTS PER MILLION 

EXPLANATION 

• Railroad district, Nevada (K. B. Ketner and J. F. Smith, Jr., 

unpub. data) 

o Valley of Ten Thousand Smokes, Alaska (hydrothermally 

altered ash; Lovering, 1957, table 1) 

x Creede-Summitville, Colorado (Steven and Ratte, 1960 tables 

2, 3, 7; Ratte and Steven, 1967, tables 2, 4, 6, 14, 18, 22) 

e Funeral Peak, California (Drewes, 1963, table 4) 

L>. Bullfrog, Nevada (Cornwall and Kleinhampl, 1964, table 2) 

o Craters of the Moon, Idaho (H. A. Powers, J. G. Murtaugh, 

unpub. data) 

+ Mogollon Rim, Arizona (T. L. Finnell, unpub. data) 

® San Gabriel Mountains, California (G. J. Neuerburg, 

unpub. data) 

"' Mount of the Holy Cross Colorado (Ogden Tweto, 

unpub. data) 

FIGURE 3.-Negative correlation between fluorine and silica contents 

of nine igneous suites from the United States. 
8 GEOLOGY AND RESOURCES OF FLUORINE 

60 

0 

~ 

E9 E9 0 

55 0 

® ® 

1- v 

z ® UJ 

u 

r:c E9 

UJ 6 

a.. 50 

z 0 

6' 6 

U5 E9 E9 E9 0 

0 0 

0 ~ 0 0 

45 X 8 0 0 

X 

8 0 

0 

40 

35'--------'-----__j_ _____ .i__ ____ _J 

0 500 1000 1500 2000 

FLUORINE, IN PARTS PER MILLION 

EXPLANATION 

6 Basalt, Bullfrog, Nevada (Cornwall and Kleinhampl, 1964, table 2) 

o Basalt, Cortez, Nevada (Gilluly and Masursky, 1965, p. 73: table 9) 

® Andesite, Klondyke, Arizona (Simons, 1964, p. 71, 72, 90) 

x Basalt, southeastern New Mexico (C. L. Jones, unpub. data) 

® Basaltic andesite, Steamboat Springs, Nevada (White and others, 1964, 

table 1, analysis 14) 

• Basalt and andesite, Blue Range, Arizona and New Mexico (Ratte and 

others, 1969, table 6) 

o Basaltic andesite, Twin Buttes, Arizona (J. R. Cooper, unpub. data) 

v Basalt, Horse Creek Valley, Nevada (Harold Masursky. unpub. data) 

EO& Olivine basalt and andesite, Funeral Peak, California (Drewes, 1963, 

table 4) 

Basalt, Lassen County, California R. L. Smith, unpub. data) 

Basalt, South Victoria Land, Antarctica (W. B. Hamilton, unpub. data) 

o Olivine basalt and trachybasalt, Hallett volcanic province, Antarctica 

(Hamilton, 1972, tables 2, 3) 

FIGURE 4.-Negative correlation between fluorine and silica contents of basalts and andesites from the Western United States and Antarctica. 

taneously through assimilation of chemically contrasting 

wallrocks. In the granitoid rocks, fluorine varies inversely 

with silica (fig. 5). Lee and Van Loenen (1971, table 9) 

showed that the quartzite wallrocks adjacent to the highsilica granitoid rocks contain an average 200 ppm F 

whereas the shale and limestone wallrocks adjacent to the 

low-silica granitoid rocks contain an average 1,300 and 

600 ppm F respectively. According to Lee and Van Loenen 

( 1970, p. D 199), most of the fluorine in the granitoid rocks 

is in biotite. Biotite content varies from less than 5 weight 

percent in rocks of about 75 percent silica to more than 25 

percent in rocks of about 65 percent silica. Interestingly, 

fluorine content of the biotite is highest (about 10,000 

ppm) in rocks of about 75 percent silica and lowest 

(2,500-5,000 ppm) in rocks of about 65 percent silica. 

These relations suggest that the biotite took up what 

fluorine was available in the magma as it crystallized. 

Moreover, it appears that biotite in the more mafic rocks 

could have taken up more fluorine had it been available. 

Total fluorine content of these rocks thus depended on 

total fluorine available in magma and assimilated wallrock, and amount of biotite formed from the magma. 

Despite the likelihood of some initial fluorine in the 

magma, the data indicate that fluorine distribution in 

comagmatic igneous rocks of different composition need 

not be wholly dependent upon magmatic differentiation. 

Aplites in the southern Snake Range that are younger 

than the granitoid rocks just discussed, and that were 

intruded probably without appreciable assimilation, 

show a different fluorine-silica relation and therefore a 

different origin from that of the granitoid rocks (fig. 5 ). 

Fleischer and Robinson (1963, p. 63) indicated an 

average of 380 ppm F for 69 metamorphic rocks of a variety 

of types. 

Sedimentary rocks, except for shales, oceanic sediments, 

and phosphorites, contain generally lower amounts of 

fluorine than do igneous rocks, as shown in the following 

table based mostly on Fleischer and Robinson (1963, table 

IV). 

Rock type 

Limestone ....................................... . Dolomite ........................................ . 

Sandstone and graywacke .............. . Shale ............................................... . Oceanic sediments .......................... . Volcanic ash and bentonite ........... . Evaporites ....................................... . 

Coal ................................................ . Phosphorite .................................... . 

Fluorine, average in parts per million 

(number of samples in parentheses) 

220 (98) 

260 (14) 

200 (50) 

940 (82) 

730 (79) 

750 (270) 

200 (30) 1

50-190 (10) 

231,000 (60) 

1 Range for coals of Southwestern United States used in 10 powerplants, according to 

Swanson and Vine (1972). 2Average for Phosphoria Formation, Western United States, (Gulbrandsen, 1966, table!). 
GEOCHEMISTRY OF FLUORINE 9 

1-

z 

UJ 

u 

rc 

UJ 

a.. 70 

z 

. 

6' 

u; 

65 

indicate an average content of 291 ppm F (H. T. 

Shacklette, written commun., 1973). These values are substantially below the averages for most crustal rocks. 

On the basis of average fluorine contents of igneous 

rocks, Fleischer and Robinson (1963, p. 67) estimated the 

average content of the continental crust to be 650 ppm. 

The average fluorine content of 533 volcanic rocks (rhyolites, andesites, and basalts) compiled for this report is 660 

ppm, which is perhaps fortuitously close to the crustal 

estimate of Fleischer and Robinson. 

ABUNDANCE OF FLUORINE IN GASSES 

AND WATERS 

Some gases and waters of volcanic origin long have been 

acknowledged as containing large amounts of fluorine 

(Zies, 1929; Fenner, 1933). Zies estimated large tonnages of 

fluorine being exhaled from cooling volcanic tuff in the 

Valley of Ten Thousand Smokes, Alaska, and Fenner, 

quoting Perret (1924) and other early observers, described 

vast volumes of fluorine-bearing gas and extensive 

fluorine-bearing sublimates given off in the eruption of 

Vesuvius and other Italian volcanoes. The hydrothermally altered volcanic rocks of the Valley of Ten 600~·----------~------------~------------~ 500 1 ooo 1500 Thousand Smokes contain fairly abundant fluorine 

FLUORINE, IN PARTS PER MILLION (500-2,100 ppm, Lovering, 1957). 

EXPLANATION 

• Aplite (Oligocene) of Pole Canyon-Can Young Canyon area 

(Lee and Van Loenen, 1971 table 10) 

0 Quartz monzonite (Jurassic) of Pole Canyon- Can Young 

Canyon area, (Lee and Van Loenen, 1971, table 6) 

0 Granodiorite and quartz monzonite (Jurassic) of Snake CreekWilliams Canyon area (Lee and Van Loenen, 1971, table 51 

FIGURE 5.-Correlation between fluorine and silica contents of hybrid 

granitoid rocks of Jurassic age and of aplite of Oligocene age from 

the southern Snake Range, Nevada. 

Carpenter (1969) indicated that the average fluorine 

contents of recent oceanic sediments range between 450 

and 1,100 ppm. Sediments from freshwater lakes have 

similar fluorine contents. Analyses of some mineral components of sediments indicate averages ranging from 50 

ppm F (opal) to 1,560 ppm F (glauconite); carbonate 

minerals ranged from 280 to 1,075 ppm F (Carpenter, 1969, 

table 2). 

According to J. B. Cathcart (oral commun., 1973), the 

high amount of fluorine in phosphorite may be due in 

part to the "stripping" of traces of F-1 from ground water 

by calcium phosphate minerals after sedimentation and 

burial. 

Soils, which average 285 ppm F in 327 samples, are 

richest in fluorine where they are high in clays, phosphate, 

or micas (Fleischer and Robinson, 1963, p. 66). Analyses by 

the U.S. Geological Survey's Washington laboratory of 

959 soil samples collected by H. T. Shacklette in a study of 

the geochemistry of soils throughout the United States 

The hydrofluoric acid content of "active" gases from a 

number of volcanoes, given by White and Waring (1963, 

table 1) are as follows: 

Volcano Rock type 

Hekla, Iceland..................... Basalt 

Kliuchevskii, Kamchatka.... Basalt 

Aso caldera, Kyushu ........... Basaltic andesite 

Vesuvius, Italy ..................... Tephritic leucitite 

Showa-Shinzan, Hokkaido Hypersthene dacite 

Katmai, Alaska .................... Rhyolite 

HF. in weight percent 

(number of samples 

in parentheses) 

trace (2) 

1.6 (7) 

.4 (1) 

.I (I) 

2.5 (II) 

21 (9) 

In a general way these data show an increase in fluorine 

content of gases evolved from volcanoes with successively 

higher silica contents, from basalt through dacite to 

rhyolite. The anomalously low hydrofluoric acid amount 

for the one analysis of gas from leucitite lava is not in 

keeping with the reports of large volumes of fluorine 

emanating from Vesuvius. 

White and Waring (1963, table 2) also presented data 

on the hydrofluoric acid content of fumarole condensates 

from several volcanoes, as summarized here: 

Volcano Rock type 

Hekla, Iceland..................... Basalt 

Santa Maria, Guatemala ..... Andesite 

Sheveluch, Kamchatka ........ Andesite 

White Island, New Zealand Hypersthene andesite 

HF, in milligrams per 

litre of water 

(number of samples 

in parentheses) 

13 (I) 

20.4 (I) 

38 (4) 

69 (7) 
10 GEOLOGY AND RESOURCES OF FLUORINE 

Additional data on fumarole condensates (White and 

Waring, 1963, table 3), expressed in a different way, are: 

Volcano 

Kilauea Iki, Hawaii . . . . . .. Basalt 

Ebeco, Kurile 

Rock type 

Islands......................... Augite andesite 

Showa -Shinzan, 

Hokkaido....... ............... Hypersthene dacite 

Fluorine, in parts 

per million (number of 

samples in parentheses) 

20 (I) 

2.4 (I) 

195 (I) 

Again, fluorine content seems to increase with increasing silica content of the source lava, from basalt 

through andesite to dacite. 

Sublimates of volcanic fumaroles and eruption clouds 

were also reported by White and Waring (1963, table 5): 

Volcano Rock type 

Fluorine, in 

weight percent 

(number of samples 

in parentheses) 

Paricutin, Mexico ................ Basalt-andesite 0.55 (2) 

Bezymyannyi, Kamchatka .... Andesite .0067 (1) 

Valley of Ten Thousand 

Smokes, Alaska................... Rhyolite 14.9 (1) 

The general fluorine-silica correlation is evident here, too. 

Pertinent to the probable occurrence of fluorinebearing condensates associated with volcanic materials 

are the data on fluorine content of tephra erupted from 

the volcano Hekla, Iceland, in 1970. Thorarinsson (1970, 

p. 47) reported as much as 2,000 ppm Fin silicic tephra 

erupted in early phases of the 1970 eruption. This is a 

notably high amount compared to the 180 ppm average 

for Iceland basalts (Barth, 1947). Much of the fluorine in 

the silicic tephra was probably in the form of a readily 

soluble condensate, inasmuch as surface waters have 

rapidly leached fluorine from tephra shortly after Hekla 

eruptions (Stefansson and Sigurjonsson, 1957). 

The fluorine contents of gases extracted from igneous 

rocks, presented by White and Waring (1963, tables 6, 7), 

are summarized below: 

Rock type 

Basalt .............................................. . 

Andesite, dacite .............................. . 

Obsidian ......................................... . 

Granite ........................................... . 

F2, in volume percent 

(number of samples in parentheses) 

6.16 (8) 

2.03 (5) 

3.19 (6) 

2.27 (2) 

Here there appears to be no correlation of fluorine with 

silica, and basalts appear to contain gases carrying rather 

high amounts of fluorine. 

White and Waring (1963, table 4) gave the following 

data on the variation in fluorine content with temperature of fumarolic gases of Showa-Shinzan: 

Temperature, oc Fluorine, in parts per million 

238 

169 

35 

A clear decrease in fluorine content with falling temperature is evident. 

White, Hem, and Waring (1963, tables 1-27) compiled 

data on the fluorine content of subsurface waters. The 

data for ground waters collected in specific rock types, 

or as specific water or environment types are summarized 

in the following list: 

Rock or water type Fluorine, average in parts per million 

(number of samples in parentheses) 

Granite, rhyolite, etc ......................................... . 

Gabbro, basalt, ultramafic. ............................... . 

Andesite, diorite, syenite ................................... . 

Sandstone, arkose, graywacke ........................... . Siltstone, clay, shale .......................................... . 

Limestone .......................................................... . 

Dolomite ........................................................... . 

Other sedimentary rocks ................................... . 

Quartzite, marble .............................................. . 

Other metamorphic rocks ................................. . 

Unconsolidated sand and gravel ...................... . 

Sodium chloride connate waters ...................... . 

Sodium and calcium chloride connate waters .. 

Sulfate-bicarbonate connate waters .................. . 

Spring waters similar to sodium 

chloride connate waters ................................. . 

Spring waters similar to sodium and 

calcium chloride connate waters .................. .. 

Thermal waters, volcano-associated geysers .... .. 

Thermal sodium chloride-bicarbonate volcanoassociated waters (nongeyser) ....................... .. 

Volcano-associated acid sulfatecholoride springs ........................................... . Volcano-associated acid sulfate springs .......... .. 

Sodium bicarbonate-boron spring waters ....... .. 

Thermal waters associated with epithermal 

mineral deposits ............................................ . 

Non-thermal saline acid waters from mines, etc. 

Travertine-depositing spring waters ............... .. 

Thermal waters probably meteoric in origin .. .. 

Saline waters associated with salt 

deposits, etc ................................................... . 

0.9 (14) 

.2 (12) 

.1 (4) 

.4 (16) 

.6 (18) 

.3 (14) 

.6 (5) 

.4 (4) 

.2 (7) 1.3 (13) 2.6 (16) 

3.1 (5) 

2.0 (3) 

4.5 (7) 

2.1 (5) 

1.3 (6) 

S6.1 (12) 

44.1 (6) 

528.4 (3) 

.6 (6) 

.5 (5) 

5.4 (11) 

2.3 (3) 

4.2 (5) 

.3 (3) 

7.7 (8) 

•Excludes one water sample containing 4.0 ppm F collected from hornblende gneiss, 

Transvaal, Republic of South Africa. 2£xcludes one water sample containing 24 ppm F collected from lake beds, Bruneau, 

Idaho. 5Five waters associated with rhyolite, dacite, and other silicic volcanic rocks average 

10.0 ppm F; 7 waters associated with andesite and basalt average 11.4 ppm F. •Four waters associated with rhyolite average 5.8 ppm F; 2 waters associated with 

andesite and basalt average 0.8 ppm F. S£xcludes one strongly acid hot-spring water sample containing 806 ppm F collected 

from White Island (andesitic volcano), New Zealand. 

As seen from the preceding list, the fluorine content of 

waters collected from specific rock types in general reflects 

the relative abundance of fluorine in those types of rocks. 

The average fluorine content of 123 water samples from all 

rock types is 0.4 ppm. Connate waters of all types contain 

much higher amounts of fluorine; 26 samples average 2. 7 

ppm. Still higher are thermal waters associated with volcanoes and epithermal mineral deposits, and related 

waters; 51 samples average 5.4 ppm F. Notably nine 

thermal waters associated with silicic volcanoes average 

8.1 ppm F whereas nine thermal waters associated with 

mafic volcanoes average 2.8 ppm F. 

Fleischer and Robinson (1963, fig. 3) showed the distribution of fluoride content of ground waters, by counties, 

in the United States. A generalization of their map is 

shown as figure 6. Significance of the data in figure 6 is 

discussed in the following section on the geochemical 

cycle of fluorine. 

Livingstone (1963, tables 6, 7, 9-16, 18, 23, 25, 26) 

presented data from which it is computed that river and 
48° ·-- ·-- ·-. ·-- ·-- ··- ··- ··~ ··- ··- ·-- ·-- ·-~ ·-- ·-- -- -- -~ -- -- -- -- -. -- -- . - . - -- 48° 

46° 

44° 

1"' 

24° 0 500 MILES I I I I I I I I I I I 0 500 KILOMETRES 

22° 

FIGURE 6.-Distribution of fluoride content of ground water in the United States, generalized from Fleischer and Robinson (1963, fig. 3). Shaded areas indicate. 1.5 ppm For 

higher in ground water. 

0 

tr1 

0 

@ 

tr1 

..... 

~ 

{J) 

~ ><: 

0 

'TJ 

'TJ 

t'"" 

e 

0 

~ 

~ 

-
12 GEOLOGY AND RESOURCES OF FLUORINE 

lake waters of North America have an average fluorine 

content of 0.25 ppm (101 samples). (Compare Correns' 

( 1956) estimate of 0.26 ppm F as the mean content of river 

waters.) Livingstone (1963, p. G41) also computed from 

the data of Konovalov (1959) that the mean fluorine 

content of rivers in most of the U.S.S.R. is about 0.09 ppm. 

Only the Rio Grande system seems abnormally high in 

fluorine among the systems averaged in the North 

American estimate given in the preceeding paragraph. 

Nine samples average 0.6 ppm F (Livingstone, 1963, table 

16). 

In addition, 7 samples of surface waters from Devils 

Lake basin, North Dakota, have an average fluorine 

content of 1.2 ppm, and 11 samples of surface waters from 

the Basin-Range province (as defined by Gilbert, 1928, p. 

I) and adjacent closed basins have an average fluorine 

content of 5.3 ppm (Livingstone, 1963, tables 20, 19). 

Fleischer and Robinson ( 1963, p. 72) on the basis of 

newer data endorsed the value of 1.2 mg/1 (milligrams per 

litre) (1.2 ppm essentially) for the fluorine content of 

Pacific and Atlantic sea waters given by Thompson and 

Taylor (1933). 

GEOCHEMICAL CYCLE OF FLUORINE 

A review of the foregoing data allows some generalizations on the geochemical cycle of fluorine, but because 

data are incomplete or lacking on many aspects of the 

problem, much uncertainty remains. 

Fluorine contents seem to be lowest in igneous rocks 

that have been irrupted through oceanic crust, such as 

andesites and basalts in the Aleutian and Hawaiian 

Islands and Iceland. The undifferentiated Hawaiian rocks 

clearly are derived from melting of the mantle, and the 

implication is that the fluorine content of the mantle is no 

higher than that of the basalts derived from it. Additional 

detailed chemical data on oceanic basalts other than 

Hawaiian are needed to indicate if mantle elsewhere in the 

world has similar fluorine compositions. 

Some Hawaiian basalts that have migrated to shallow 

chambers have become differentiated before eruption, and 

this differentiation caused not only an increase in silica 

content, but also a substantial increase in fluorine content. 

It is evident that such magmatic differentiation does concentrate fluorine, as many earth scientists long have 

conjectured. 

Basalts irrupted through continental crust tend to 

contain appreciably higher fluorine than do oceanic 

basalts. These continental basalts tend to have alkalic 

affinities; whether their higher fluorine content resulted 

from differentiation toward alkalic composition or from 

contamination by fluorine-enriched continental crust is a 

moot point. More data are needed on the fluorine content 

of alkalic rocks differentiated from mantle-derived basalts 

in the oceanic environment to test if differentiation or contamination might be dominant in the continental 

environment. Silicic rocks that contain high amounts of 

fluorine also tend to be alkalic. Like the mafic rocks, those 

that show strong alkalic affinities tend to occur in 

continental environments. Even though differentiation 

toward silicic and alkalic types clearly does occur in the 

oceanic environment the process may be enhanced where 

it occurs in continental crust. Certainly, rocks-either 

silicic or mafic-that contain unusually high amounts of 

fluorine-5,000 ppm (0.5 percent) and higher-have 

formed in continental crust. 

Although silicic igneous rocks as a whole average 

higher in fluorine than do mafic rocks, many silicic 

igneous rocks have fluorine contents as low as those that 

characterize most mafic rocks (fig. 7). The siliceous 

character of such rocks likely was not acquired through 

magmatic differentiation. 

The data on distribution of fluorine in granitoid rocks 

of the southern Snake Range, Nev., indicate that fluorine 

content of the rocks was dependent on initial availability 

of fluorine and on the abundance of minerals that were 

capable of taking up fluorine. The negative correlation of 

fluorine and silica in numerous suites of igneous rocks 

thus might best be explained if their fluorine content 

represents that of the deep crust in which they were 

generated, and if they were not subject to strong magmatic differentiation after initial melting and before 

extrusion or emplacement in the upper crust. Such rocks 

likely changed composition substantially throughout 

their fluid history, but probably by assimilation of 

(reaction with) wallrocks rather than by fractional 

crystallization. 

The evidence that crustal composition controlled 

fluorine content of some igneous rocks, and the strong 

association of fluorine with alkalic rocks, raise the 

question of the origin of alkalic rocks and the high 

concentrations of fluorine accompanying them. Without 

discounting the possibility of fractionating alkalic rocks 

from the mantle to account for their high alkali and 

fluorine contents, it seems quite possible that some alkalic 

rocks originated because alkalis became segregated and 

concentrated by the fluxing action of fluorine that was 

intrinsically high at a site of magma generation in the 

crust. Phosphatic rocks, for example, if melted, would 

develop a phosphate- and fluorine-enriched magma 

chemically similar to some known alkalic rock types. 

Some alkalic rocks therefore may reflect origin in fluorineenriched segments of the crust, and their fluorine content 

may have been initial rather than a result of magmatic 

differentiation. 

The fluorine content of metamorphic and sedimentary 

rocks is similar to that of most igneous rocks. If some igneous rocks are generated by melting of crustal rocks, 

including metamorphic, sedimentary, and preexisting igneous rocks, it is expectable that they contain generally 

similar amounts of fluorine. Conceivably some igneous 

rocks would contain less fluorine if it were driven off 

during melting that formed the magmas, and conceivably 
GEOCHEMISTRY OF FLUORINE 13 

1-

z 

w 

{.) 

a: 

w 

a.. 

z 

. 

d' 

(i) 

. ': t • ... : . ~ : . . . .. . ' . :- ..... 

.. : :..;:, 

• : I " • I J. • : -: . . . . . : . :. 1 . . . .. . : .. . . . . 

I . . t . ., . 

. . . . . .. .. I • ' 

:" 

:: :. .... . 

• I . "C 

-- . I .. . 

!- • 

. f: ; ~ :1-!t: . . , .. . $ ~i ! 

• • fl • I 

I 

' 

I .: I 

. . ' . 

... :.~til ~~:=r; 

!" 

~ . . : . . . ' 

'· : . I 

. . 

i!) • 

. . 

. . 

. . . . 

35 0~----~~~----~~----~~~----~~----~2~5~00----~~~----~~----~~------~~----~ 

FLUORINE, IN PARTS PER MILLION 

FIGURE 7.-Scatter diagram showing relation of fluorine to silica in 532 volcanic rocks. Data from published sources, and unpublished 

U.S. Geological Survey sources. 

some igneous rocks would contain more fluorine if the 

parent rock contained unusual concentrations of fluorine. 

The common occurrence of a bimodal assemblage of 

young alkali rhyolites and basalts, for example in the 

Western United States, both enriched in fluorine, provides 

insight into the cause of some fluorine enrichment. The 

basalts undoubtedly are mantle-derived; fluorine 

enrichment of a type such as that at Craters of the Moon, 

southern Idaho, could have occurred by differentiation 

following irruption of magma into a high level of the 

crust. A strong negative correlation of fluorine and silica 

in these rocks (fig. 3), however, suggests concentration of 

fluorine by a mechanism other than magmatic differentiation. The related alkali rhyolites in the same region, 

compositionally akin to the young basalts and of similar 

age and geologic setting (erupted through tensional structures), likewise may have been mantle-derived. For such 

rhyolites to have been derived from the mantle, extreme 

fractionation of the more mobile and volatile components of mantle material must have occurred. Such fractionation by partial melting of mantle material could 

account for the unusually high fluorine contents of the 

rhyolites. 

The fact that intrusive rocks tend to contain more 

fluorine than do extrusive rocks indicates that fluorine 

may be lost as a volatile component in a low-pressure 

environment. The data showing abundant fluorine in 

some volcanic exhalations corroborate this conclusion. 
14 GEOLOGY AND RESOURCES OF FLUORINE 

Some intrusive rocks are surrounded by halos of altered 

rocks in which fluorine is substantially enriched, suggesting that even magmas under relatively high pressures lose 

fluorine. 

Analytical data on the fluorine content of volcanic 

gases, fumarole condensates and sublimates, and thermal 

waters associated with volcanoes, indicate a tendency for 

more fluorine to be exhaled by silicic volcanoes than by 

mafic ones. This relation is in keeping with the fact that 

silicic igneous rocks generally contain more fluorine than 

mafic igneous rocks, but more data are needed to correlate 

fluorine contents of exhalations directly with fluorine 

abundance in magmas. Data on the fluorine content of 

alkalic lavas and their exhalations particularly are needed. 

Nevertheless, it seems a fair conclusion that the higher the 

fluorine content of the magma, the more fluorine is given 

off in volatile phases, whether the magma is extruded or 

emplaced below the surface. Further, the temperature data 

from Showa-Shinzan, Hokkaido, suggest that the higher 

the temperature of the magma, the more readily fluorine 

is driven from the magma. 

Whether a magma is intruded and cooled below the 

surface, or extruded, it seems clear that release of volatile 

components-including fluorine-from magma results 

primarily from pressure decrease, due to magma rise or 

rock fracturing. Crystallization of magma by itself would 

not be expected to drive off much fluorine, although the 

fluorine content of the residual magma would increase 

unless the minerals that crystallized included some 

capable of taking up fluorine (micas or amphiboles). 

Noble and others (1967) showed that devitrified silicic 

volcanic rocks have about half of the fluorine content of 

glassy equivalents (0.09 percent F, average of 89 samples, 

compared to 0.21 percentF,averageof72 samples), indicating that appreciable fluorine is lost upon crystallization 

(largely devitrification). This difference may be the result 

of lack of minerals in the crystallized silicic rocks capable 

of taking up fluorine. 

The fact that soils average substantially lower in 

fluorine content than do rocks of the crust shows that 

fluorine tends to move into ground and surface waters 

during weathering. 

Apparently ground waters generally dissolve fluorine 

from the rocks with which they are in contact in proportion to the abundance of fluorine in the rocks. For 

example, ground water in North Carolina and Virginia 

shows high fluorine contents only in areas where granites 

are known to contain fluorite. An arc extending from 

northwestern Ohio westward through Iowa and northwestward through the Dakotas has ground waters with · 

high-fluorine content. The arc is underlain by glacial 

matena1s of the Mankato, Cary, and Tazewell Stades of the 

Wisconsin Glaciation, but not by those of the Iowan, 

Kansan, or Nebraskan Glaciations. Possibly the fluorine 

content of the waters can be related to the composition 

of glacial material, or in a complex way to bedrock geology. In southern Arizona some areas where ground waters 

have high-fluorine values coincide with areas of volcanic 

rocks with high-fluorine contents. 

Undoubtedly meteoric waters transfer some fluorine 

from the atmosphere (derived mostly from the oceans and 

in part from volcanic exhalations and industrial sources) 

to ground water near the Earth's surface, but data are 

needed to quantify the amount, seemingly less than that 

supplied to ground water from rocks. 

Surface waters of the United States, composed of 

meteoric water mixed with a certain amount of fluorinebearing ground waters, appear to stabilize with a fluorine 

content of about 0.25 ppm. These waters flow into ocean 

waters containing 4-5 times as high a concentration of 

fluorine, and thus tend to dilute the ocean waters. 

Barth (1947, p. 422) argued that only a fraction of 1 percent of the fluorine derived from weathered and eroded 

rocks remains in solution after it reaches the sea; the rest is 

precipitated. According to Carpenter ( 1969) calcium 

carbonate precipitation dominates the removal of dissolved fluoride from sea water; precipitation of calcium 

phosphate undoubtedly removes substantial amounts. 

Of course it is apparent that much fluorine is transported by rivers to the sea in suspension, contained in clay 

minerals that formed by weathering and in micas that are 

residual from weathering. Carpenter (1969) concluded 

that most of the fluorine which moves from the land to the 

sea does so in this fashion. 

A comprehensive report on the geochemistry of fluorine 

(Koritnig, 1972) was published after this report was 

written. 

ELEMENT ASSOCIATIONS 

By R. E. VAN ALSTINE and D. R. SHAWE 

Spectrographic analyses (Allen, 1952; Heyl, 1967, p. 

25-26; Hall and Heyl, 1968, p. 658-661; Trace, 1960) reveal 

that minor elements associated with fluorite include 

aluminum, antimony, barium, beryllium, boron, carbon, 

cerium, copper, dysprosium, erbium, europium, gadolinium, iron, lanthanum, lead, lithium, lutetium, magnesium, manganese, neodymium, niobium, potassium, 

praseodymium, samarium, scandium, silicon, sodium, 

strontium, sulfur, terbium, thorium, thulium, tin, 

uranium, ytterbium, yttrium, zinc, and zirconium. In 

addition, galena associated with fluorite commonly 

contains silver and antimony, and the associated 

sphalerite generally contains cadmium, gallium, and 

germanium. The geochemical association of fluorine with 

beryllium in certain silicic volcanic rocks of the Western 

United States has been cited by Staatz and Griffitts (1961), 

Griffitts and Powers (1963), and Shawe and Bernold 

(1966). Coats, Goss, and Rader (1963) showed regional 

variations in the fluorine content of glassy rhyolitic volcanic rocks of the Western United States, and Coats (1956) 
GEOGRAPHIC DISTRIBUTION OF FLUORINE IN IGNEOUS ROCKS 15 

cited the correlation of fluorine and uranium contents in 

these Cenozoic volcanic rocks. Worl (U.S. Geol. Survey, 

1970) found anomalous amounts of molybdenum in Precambrian wallrock next to the fluorspar deposits of the 

Northgate district, Jackson County, Colo. Altered wallrock contains as much as 800 ppm Mo, and the amount 

decreases away from the vein. For fluorite from Illinois, 

Virginia, and various districts of Colorado, New Mexico, 

and Utah, Blanchard (1966) gave the contents of strontium 

and yttrium, the two most abundant and widespread 

minor elements of the fluorite. Fluorite from the Illinois 

district (Ruch, 1968, p. 5) showed, in parts per million: 

< 0.04-0.60 scandium; 0.17-1.5 europium; 0.2-9.4 

dysprosium; 0.2-4.1 samarium; 1-113 copper; 5-188 

sodium; < 0.1-1.2 manganese; <0.2-0.8 cobalt; <1-10 

chromium. Fleischer (1969, p. 36-37; table I) pointed out 

that fluorite from granitic pegmatites contains notable 

concentrations of the heavy lanthanides (dysprosium, 

holmium, erbium, ytterbium, etc.) and fluorite from 

alkalic rocks contains notable concentrations of the light 

lanthanides (lanthanum, cerium, praseodymium, 

neodymium, etc.). 

Perhac and Heinrich (1964, p. 238) listed cerium, 

lanthanum, praseodymium, neodymium, and samarium 

as the major rare-earth constituents of fluorite-bastnaesite 

ore in the Gallinas Mountains, N. Mex. 

No clearcut preferred associations of fluorine with 

specific elements are evident from the foregoing data. 

Nevertheless, considerable data, both published and in the 

files of the U.S. Geological Survey, show that fluorine has 

a common association with a geochemically coherent 

group of elements including beryllium, lithium, manganese, niobium, tin, tungsten, uranium, yttrium, lead, 

and zinc. The data cited in the previous paragraphs are 

a catalog of a variety of types of associations: minorelement contents of fluorine minerals; minor-element 

compositions of rocks containing abnormal fluorine; and 

anomalous minor-element contents of rocks associated 

with fluorine mineral concentrations or ore bodies. This 

variety perhaps explains the lack of consistency in the data 

cited of association of fluorine with a specific suite of 

elements. On the other hand, geochemical data reveal a 

common association of fluorine with most or all of the elements of the assemblage beryllium-lithium-manganeseniobium-tin-tungsten-uranium-yttrium-lead-zinc in certain rock types, particularly alkali rhyolites (Shaw, 1966, 

p. C2ll) and granites (Hawley and others, 1966, p. Cl44, 

Cl45), and several fluorine-bearing ore types, including 

greisens (Hawley, 1969, p. A25, A31, A33, A36, A38; Sainsbury, 1964a), pegmatites (Norton and others, 1962, p. 

111-118; Norton, 1970, table 2; Sheridan and others, 1957, 

p. 7, 16, 18), contact metamorphic aureoles (Sainsbury, 

1964a; Warner and others, 1959, p. 114-116, 118, 122-125), 

certain veins (Sainsbury, 1964a, l964b; Sainsbury, 1969, 

p. 68; Hewett, 1964, p. 1456), low-temperature stratiform 

deposits in sedimentary rocks (Shawe, 1968, p. 1155), hotsprings deposits (Warner and others, 1959, p. 39; Hewett 

and Fleischer, 1960, p. 43; Hewett and others, 1963, p. 24, 

26, 29-30), and saline lake brines. 

GEOGRAPHIC DISTRIBUTION OF 

FLUORINE IN IGNEOUS ROCKS 

By D. R. SHAWE 

Igneous rocks with high fluorine contents occur in two 

major geographically restricted areas in the United States, 

and are of two markedly contrasting ages. One area is a 

broad belt of dominantly Paleozoic rocks that extends 

from southern Maine southwestward into Alabama, and 

the other of dominantly Tertiary rocks that forms a Ushaped area extending from southwestern Montana 

southward through southern Idaho, eastern Nevada, and 

western Utah, into southern California, eastward through 

southern Arizona to southwestern New Mexico, and 

thence northward through western Colorado (fig. 8). 

Small patches of fluorine-rich igneous rocks occur elsewhere, notably in southern Illinois-southeastern Missouri 

and in central Arkansas. 

The areas shown in figure 8 are somewhat generalized 

and are based on the known distribution of chemically 

analyzed igneous rocks containing 0.1 percent or more 

fluorine or microscopically recognizable fluorite or topaz. 

The rocks include alkali basalts and rhyolites (topazbearing rhyolites in part), alkali gabbros and granites, 

several other varieties of alkalic rocks, kimberlites, pegmatites, and greisenized granites. Many of these igneous 

rocks contain either fluorite or topaz as accessory minerals. 

Notably, in these fluorine-rich provinces mafic rocks as 

well as silicic rocks contain high amounts of fluorine. 

Figure 8 also distinguishes zones, generally within the 

broad fluorine-rich igneous provinces, where fluorinerich igneous rocks are especially abundant, or where some 

igneous rocks contain 0.2 percent or more fluorine or 

abundant fluorite or topaz. 

Locations of topaz-bearing rhyolites are shown in 

figure 10. 

Because of lack of data in places outside the areas of 

fluorine-rich igneous rocks shown on figure 8 some other 

fluorine-rich areas may exist but cannot be large. 

In the Western United States a distinction can be made 

between fluorine-rich trachytes, trachybasalts, and phonolites of early to middle Tertiary age in central Montana, in 

parts of Wyoming, Colorado, and New Mexico, and in 

western Texas, and alkali rhyolites of middle Tertiary and 

younger age elsewhere throughout the Western United 

States fluorine-rich igneous rock province (Lipman and 

others, 1972, p. 222-226). In some parts of the Western 

United States fluorine-rich igneous rocks of Tertiary age 

are closely associated with older fluorine-rich igneous 

rocks. For example, phonolites of Tertiary age in the 

vicinity of Cripple Creek, Colo., are intruded into the 
"0 ~ ,,. 64 " 48 " ~ 128° V ~-- -. ~Lo<. o<.V V ~.lV .l .l.. .l1L • •v L VO J. VU .V.. .lVL .lVV :::70 ='V ::;> .. JL :JV 0 0 OU o-. 04 O V '0 IV f"'T <C.. fV VU 

46" 

4 4" 

38" 

36' 

24' 

22" 

--,--,-____ _ I I --------- f\ 

I I ---l----------,--. I 

"'~ s ,

1 

-~·cr 0 1 I 1 , 1 r -~-,""-'~ 1 

·~-----~-- I Nl -f I I., M 0 N 'f A ,, A I

I N 0 H T H D A K 0 T A\MI I N~ OT A 

O R eGoN 

------r---

I 

I 

I 

) I \ 

; rl ----------.) / ________ _, '-, 

'I ; S O U TH DAKOTA ! "-..._ 

I I J 

I i \------- , ' W Y 0 M I N G 1..--------, \.._ --- 1 ...... -.._( o:::---

1 " ' 

I I \ I 0 w A _) I \ l_ I I\ E u H A s K A ... )I I -7-nt\--J.___ 1 s\ 

I A ' ~------~\l \. 1~0 1 ~DI'NA \ T I IJ L _________ ~) \ ( "''-~ A f/ 1 <, ' 1 r) 1 

, 15 I ' I 1

1 M 1 S S 0 U R I t ) J"'-J 

I 

---c-: 

'"-, 

-,, 

K A NS A S · ...._ ll""-.1". 1

. U C 'K I 1 0 \ _. - K EN 

I I . - -

---- L ___________ ~ -------, < _ __,-- ~~:: E J:----- t" '< T ENN· 

I I I ) ___ ,.- • J 0 KLA JI 0 :\1 A I SAS I---~ ' I I I A R K :Y:'j ,r I j ~ I 0 r : \ 

_,'-v'"--... -~,.,..--,__L ,' I ~ 1 M 1 S S I S- I A L A B 

~--- ~ S I PPI i I / 

\ ' 

\ L-~- L ouJ:srANA 1'\~~ 

TEXAS 

0 

' ' ,~- ""'-'" "'-.... ' \ I 

' \ 

I 

' \._ 0 500 MI LES 

0 500 KI LO METRES 

86* 84° 

FIGURE B.-Distribution of fluorine-rich igneous rocks in the United States. 

4 6 ' 

4 4 " 

42" 

40" 

EXPLANATION J 

Area of occurrence of 

igneous rocks that 30" 

contain 0.1 percent 

or more fluorine or 

recognizable fluorite 28" 

or topaz 

Area where fluorinerich igneous rocks j 26' 

are especially a bundant, or contain 0.2 

percent or more .....1 24 " 

fluorine or abundant 

fluorite or topaz I 

22' 

...... 

0"> 

0 

t"'1 

0 

r 

0 

0 

>-<: 

;;.. 

z 

tl 

::e 

t"'1 

(J) 

0 

c 

::e 

n 

t"'1 

(J) 

0 

'Tj 

'Tj 

r 

c 

0 

::e 

z 

t"'1 
GEOLOGIC ENVIRONMENTS AND DISTRIBUTION OF FLUORINE 17 

Pikes Peak Granite of Precambrian age, suggesting the 

possibility that the high fluorine content of the Pikes Peak 

resulted in fluorine enrichment in the phonolites. Despite 

the presence of older fluorine-rich igneous rocks, the distribution of those of Tertiary age alone defines the extent 

of the fluorine-rich igneous province in the Western 

United States. 

GEOLOGIC ENVIRONMENTS AND 

DISTRIBUTION OF FLUORINE 

By D. R. SHAWE and R. E. VAN ALSTINE 

Fluorine concentrations occur in a wide variety of geologic environments and in a multitude of forms. The deposits can be classified in a number of ways; we present 

the following classification (with some examples given) 

mainly to show the great range and complexity of deposit 

types; the classification will facilitate our descriptions of 

individual deposits and evaluations of deposit types in 

later parts of this report. 

A. Volcanic rock associations 

1. Veins (Wagon Wheel Gap, Colo.) 

2. Mantas (Sierra Cuchillo, N. Mex.) 

3. Pipes (Thomas Range, Utah) 

4. Disseminated deposits (Thomas Range, Utah) 

5. Tuffaceous lake beds (Rome, Oreg.) 

6. Volcanic necks and diatremes (Hicks Dome, Ill.) 

B. Intrusive rock associations 

1. Breccia stockworks (Jamestown, Colo.) 

2. Pipes (southeast Alaska) 

3. Veins (York Mountains, Alaska) 

4. Contact zones, including tactites (Iron Mountain, N. Mex.) 

5. Disseminated deposits (topaz and fluorite at 

Climax, Colo.) 

6. Pegmatites (Petaca district, New Mexico; Darby, 

Mont.) 

7. Fluorine-rich syenites and granites (Pikes Peak 

Granite, Colorado) 

8. Greisens (Lake George, Colo.) 

C. Metamorphic rock associations 

1. Layered gneisses (topaz at Evergreen, Colo.) 

2. Fluorine-bearing marbles (McAfee, N.J.) 

3. Contact metamorphic deposits with magnetitefranklinite-fluorite-apatite (northern New 

York and northwestern New Jersey) 

4. Contact metamorphic deposits with humite 

(Brewster, N.Y.) 

D. Sedimentary rock associations 

1. Phosphate rock (Phosphoria Formation, Western United States) 

2. Veins, breccia pipes, or mantas in carbonate 

rock, shale, or sandstone (Illinois-Kentucky 

district) 

D. Sedimentary rock associations-Continued 

3. Disseminations and vug fillings in carbonate 

rock (Permian of north-central Wyoming; 

Lockport, N. Y.) 

4. Disseminated deposits in volcaniclastic rock 

(Thomas Range, Utah) 

5. Tuffaceous lake beds (Rome, Oreg.) 

6. Saline beds and basin brines (Searles Lake, 

Calif.) 

E. Miscellaneous 

1. Major fault zones with fluorite (Illinois-Kentucky district) 

2. Cryptovolcanic structures (Hicks Dome, Ill.) 

Some inevitable overlaps occur in this, or any other, 

classification. Therefore, we discuss the occurrence and 

distribution of deposits according to their primary mineral character (fluorite, topaz, or phosphate) and we discuss the geology of deposits and districts geographically, 

State by State. 

FLUORINE IN FLUORITE DEPOSITS 

AND OCCURRENCES 

Fluorspar is a mineral aggregate or mass containing 

enough fluorite (CaF2) to be of commercial interest; pure 

fluorite is 51.1 percent calcium and 48.9 percent fluorine. 

Fluorite is harder than calcite (CaC03) and softer than 

quartz (Si02), two common mineral associates with which 

it may be confused, and is appreciably heavier than either 

one; it is not as heavy as barite, another common associate. 

Fluorite has a vitreous luster and a wide variety of colors, 

commonly shades of purple or green, but also white to 

yellow, green, blue, rose, purple, red, brown and purplish 

black. Fluorite generally crystallizes as cubes or 

octahedrons but may occur in massive form, crusts, 

globular aggregates showing radial fibrous textures, and 

earthy and banded cryptocrystalline forms resembling 

chalcedony. It has perfect octahedral cleavage, which with 

its characteristic crystal forms, color, heaviness, and 

hardness generally is sufficient to differentiate it from 

other minerals. Minerals other than calcite and quartz 

commonly found in fluorspar deposits are barite (BaS04), 

galena (PbS), sphalerite (ZnS), pyrite (FeS2 ), chalcopyrite 

(CuFeS2), hematite (Fep3), limonite (hydrous ferric 

oxide), manganese oxides, clay, and various oxidation 

products from breakdown of the sulfide minerals. In a few 

deposits the fluorite is accompanied by uranium, rareearth, or beryllium minerals, where they locally might be 

coproducts; major fluorspar districts with associated 

uranium minerals include Jamestown, Colo., Thomas 

Range, Utah, and Bare Mountain, Nev. (Wilmarth and 

others, 1952). 

Fluorine is widely distributed throughout the United 

States in fluorite deposits (fig. 9). The patterned areas of 

figure 9 include reported occurrences of fluorite as well as 

productive fluorspar deposits. Generally speaking, most 
12a· 126· 124 • 122· 120· 11s· 116· 114• 112• 110· 10s· 106 · 10 4 · 102· 10o· ga · 95~ 94" 92 • 90" as~ 86 " s4• 82 " so· 78" 76" 74 " n· 1o· 68 " 66" 64 " 48 " 48" 

46" 

44" 

28" 

26 " 

24 " 

118" 

~Obo., 

--- -~ <---;.:-"? ;-----.,. ______ ---T--------:- -~---;-;-~ IV ~ s "'·"' '•• ! I' ) ' . 

..

. •. ,.,.-~ p-· , I ' 'N 0 R T H D A K 0 T A

'

I 

: ., .... , j' l

'~-----~--.J •·· ... · :c:: • ., ·.. . . ' ' I -------, ' IW IS C 0 U '" 

, ' . L, . r--- " ' , I ···!h. ·" · r---g _____ _J I ' " 

o .. { .. ~·• '..-r Q)'sour u D AKOTA, _J If. E: G 0 N I ' - ' ' ----- ' 

' '"._ ' ' ,- o-..------- 1 L ----, _,)' I?'".," ' ---- - ' '"'" I 

, \ ,- , I 

I ' "'" """" ' (_ ______ 1" ) • "" ,, I'""" "" ' 

A1t' I ).!. __ 

'~- .. L..-.J 

-•-.c __ ~ ' \ ( 

L ------------~) \ ' I 

I I M I I ~· ~ SSOU R I KANSAS I 

I i\; I 

no 

I ... _j L___________ 1----

---f----- I I --,-

1 K LA II 0 M A I R K ANSA s,r-- 1 0 l A c::J ( 

I t ! ,' . I I 

I 

I 

-'..._,, ·~..-·-'-.!., 1 M!SSI S- I A L 

~"'< I ---i_ S I PPI r- . 

'~,~ •. -- \ . ~-, 

..... ""-... ' ,,. \ 

T EX AS 

CJ 

',\ 

' ' \...._ 

I / \ . \ L ~ ' L O U I S I ANA __ f,~ 

' 

0 500 MI LES 

0 500 KILOMETRES 

116" 

FIGURE 9.-Distribution of fluorite deposits in the United States, based on Worl, Van Alstine, and Hey! (1974). 

46" 

44" 

4 2" 

40" 

38" 

36" 

34" 

28" 

22" 

78" 76"· 74" 

00 

-

C"l 

t-1 

0 

t"" 

0 

C"l 

><: 

;> 

z 

t; 

:;.:l 

t-1 

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e 

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t-1 

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0 

'T1 

~ e 

0 

:;.:l 

z 

'T1 
GEOLOGIC ENVIRONMENTS AND DISTRIBUTION OF FLUORINE 19 

of the fluorspar deposits and fluorite occurrences are 

found in the mountainous regions of the Western United 

States excluding the Colorado Plateau, and in the 

Appalachian Mountains in the Eastern United States. The 

principal producing area of the United States-the 

Illinois-Kentucky district-is outside of mountainous 

regions. 

FLUORINE IN TOPAZ DEPOSITS 

AND OCCURRENCES 

Topaz (Al 2 [Si04] (OH, F)2) generally has not been 

produced as a commercial source of fluorine although the 

fluorine content of topaz is high enough to suggest a 

potential source. Topaz ideally contains 32.6 percent 

silica, 55.4 percent alumina, and 20.7 percent fluorine 

(total I 08.7 percent, less 8. 7 percent 0 for F). Topaz is hard 

(harder than quartz and softer than corundum) and heavy 

(density 3.49-3.57). Color is variable, commonly colorless 

to yellow, pink, light blue, and light green. Its hardness 

and vitreous luster have made colored topaz a valuable 

gem mineral. Topaz usually forms orthorhombic prisms 

with perfect basal cleavage. Common mineral associates 

are quartz, fluorite, tourmaline, beryl, cassiterite, wolframite, rutile, and muscovite. 

Topaz is found chiefly in silicic igneous rocks such as 

granites, granite pegmatites, and rhyolites and in veins, 

disseminated deposits, and greisens associated with these. 

It is also associated with other heavy minerals in placers 

near certain silicic intrusive rocks. 

Topaz deposits are widely distributed throughout the 

United States, as shown in figure 10. 

FLUORINE IN PHOSPHATE AND 

FLUORAPATITE DEPOSITS 

Fluorine-bearing phosphate deposits occur in rocks of 

all geologic eras from Precambrian to Cenozoic as igneous · 

apatite, sedimentary phosphorite, and guano deposits, 

and as secondary accumulations formed by weathering, 

diagenesis, and reworking of any of the primary materials. 

Fluorine is present in economically interesting amounts 

in phosphate deposits in many parts of the United States, 

and in particularly large amounts in sedimentary phosphorite deposits. The phosphate mineral of the sedimentary phosphorite deposits is carbonate 

fluorapatite-CaiO(P04,C03)6F2_ 3• The ratio ofF to P20 5 

in this mineral is about I to 10; P20 5 content in minable 

deposits ranges from 28 to 38 percent, and F content of 

mined phosphate of the Phosphoria Formation in the 

Western United States is about 3.1 percent, that of Eastern 

phosphates is 3.6-3.8 percent. Presently commercial phosphate deposits in which fluorine occurs as a potential byproduct are confined to marine sedimentary phosphorites 

of Ordovician age in Tennessee, of Permian age in the 

Western United States (southwestern Montana, southeastern Idaho, western Wyoming, and northern Utah), of 

Miocene age in North Carolina, Georgia, and South Carolina, and of Miocene and Pliocene ages in Florida, and to 

residual deposits derived from some of them. Locations 

of phosphate deposits in the United States are shown in 

figure 11. 

The phosphate deposits of the Atlantic Coastal Plain 

(Florida, Georgia, South Carolina, and North Carolina) 

are in unconsolidated rocks of Tertiary age. The deposits 

consist of quartz sand, clay, and irregularly rounded, 

highly polished, generally dark colored phosphate grains. 

The phosphate grains range in size from about 0.1 mm to 

several centimetres in diameter, but most are sand sized. 

The phosphate deposits of Tennessee are derived from 

calcareous rocks of Ordovician age. The deposits are 

residual and consist of rounded grains of sand- to silt-sized 

brown phosphate, quartz, and minor clay. Irregular 

masses of quartz and phosphate sand cemented by phosphate are common. 

The phosphate deposits of the Western United States 

(Idaho, Montana, Wyoming, and Utah) are in rocks of the 

Phosphoria Formation of Permian age. The deposits consist of consolidated beds of carbonaceous, pelletal, sandy 

phosphorite associated with black shale, chert, and limestone. 

Nonsedimentary fluorapatite deposits of a variety of 

types may have potential for byproduct fluorine production (fig. 11 ). Fluorapatite occurs with magnetite at 

Ausable, Mineville, and Trembley Mountain, N.Y., Canfield mine, Dover, N.J., and Iron Mountain, Mo.; with 

rare-earth fluocarbonates and magnetite at Scrub Oaks 

mine, Dover, N.J.; in skarn in Hurdtown, N.J.; and in 

dikes with ilmenite near Roseland and Piney River, Va. 

Fluorapatite is found in magnetite-rich contact metamorphic deposits at Iron Springs, Utah, and at the Barth 

mine, the Modarelli mine, the McCoy district, the Black 

Joe prospect, the Emery-Fisk prospect, and in the Buena 

Vista Hills, Nev. 

FLUORINE IN OTHER DEPOSITS 

Fluorite, topaz, and fluorapatite occur also in types of 

deposits other than those just described. In addition, some 

other fluorine-bearing minerals of possible economic 

significance are the fluorides, cryolite, Na3A1F6, sellaite, 

MgF2, and villiaumite, NaF; the humite group of fluorine 

hydroxysilicates; and bastnaesite, (Ce,La) (C03)F, whereas 

other still less common fluorine-bearing minerals will 

probably be of little economic significance in the future. 

Fluorine is also present in many other minerals including 

silicates like tourmaline and the micas (phlogopite, 

zinnwaldite, lepidolite, muscovite, and biotite), and 

phosphates (monazite, xenotime, and amblygonite). 

Some types of deposits are not known domestically. 

A cryolite deposit at lvigtut, Greenland, is virtually a 

monomineralic pegmatite although it contains also some 

complex fluorides, fluorite, topaz, microcline, columbite, 
48 , ·~~ ·~~ ·~~ •~~ •~~ ••v ••v ••~ ••~ ••v •v~ •vv •v~ •v~ •vv "u "v -~ "' "v uu uv u~ u' uv 'u 'V •~ '~ 'v vu vv v~ 

46' 

40' 

30' 

28' 

"' -~ --~ ---,--,---~-- ' rc--, ' : 'L 

I : ' ---------- " ' ,_ 1\ --l----------T--·1_"""'-/-... ) ~>.\1'"' ' ' ~--~ -<' • ' -

0 

'-~~---------J N I \ ~ : \ '0" --i-'.' • M 0 NT AN A IN 0 R T H D A K 0 T A\ MIN N E /--\~~1-\y •· 

' ' X ' ' I ' ' 1 t I \ j ' 1

Jilf·"' r~ I 

VI 1 1 ' \•''> ORF:GoN / , r----------; ~ ' ~~- I ( l._ , __ ,, r----------~ \. ' IW IS C 0 N SIN "" R R '"'"'• riiu,S5~~5 ei D I I I ........ "'~-- IP .[> l"-'--"]'<ll 

1

1 

A H o 1 / s u u T H D A K o T A '- _ 1\-n•''' • ~'"ou10 " )( I I ' -~ __ -----r---~~-- I I ' ___ J --- glol\11 X: w y 0. 'No L________ ~---- l - -1 bUll. Of ~~~"i t --~-----! : ',~~ ~-- --T- ''V~> ''' c > 

' 

I I )( 

X • I / ,__ 

I 

1----xo-<--, I I 

N E BRAs K A 

\ 

.., \ 

I u w A )I j 

-\ 

I I 

1\ u H l 0 '•-->,, 

~ /\ ~~K-<'h,. R'l'--"1'\~"'<-----"\~" J" -J • \ 

~ u£ 

'--""'"~'"' I • I ' '1;--------.) L LIN 0 I;; lANAI .r/ :;'r ' • (, N E \ A D A /

1 

xX< C/rmax mine X~ Urad-Henderson mine ' 1

\ 1 r NO I ,1 ~~-' \-"} ~ _ \d roine 

' 

\ uTAH I _\ E f-----------"":> I .f''- ' ~v r ' "~ ~e11e 1 

1 >0 vergreen ' ' ' r ..,.-...J "' 1 • 0 n ' '• • I ' 1 , \ ,'"~'f.' 1 

> _-::\ _ 

', • •'\ I* I '·~,'I" o I ''"'A' i w I" o" "( !,__,.,•f -'' >~-:,. o '_':---roo !Jiouotaln ·,..."' o , 

'\ 1 L --------+---- t' x ll 1 Silver Mines, ~adrson , _ Co. '--" \ '"1-J _, _______ 

.,_"' 11< /-. j___ ,-'~ ----.o d, So'" 1 "~\ 100

rN A ~ 1'1 ' f-' I ------, ------------' -- ,!--"' - /no"" "-c rtl tt 

~, ' I ','\ 1------ "----- <'-! n"' "'"' _, ---'•, -, 7° ;oe \

1 

I •• Questa m;ne 1 1 ; __ L-r ~ Br•"""' rn 

\. 1

1 

)( 

1 

~~ARizoNA I OKLAHOMA I _ 'AS~---~---1", • -~ SOl\rNA I I IARKAN>i ,r I ' ""-!2ARO 

/ : ' ' w M ' ' I c 0 : l_, I I ' I ,, 

', I I '-v-..._,""-~",.,......~~-J_ '\ I \ GEORGIA __ 

--< '-.. ' X I 1 _J "'""-'"""'~"'' 1 

.;: 1 r---- < SIPPI I ~ ""-. ',, I _ o_o,~~ d;st'fct • , , , , , , / ~ R~ck 1 ford \ 

'- ..1. --1.; - • \ • I --~ ----~ -- -I '" Streeter placer, Llano uplift \ L---; \ 11 c;:;,~ ~ '-\ 6 ( LOUISIAN~\~ l 

', ,---, ~ ..... ,.. '\ 

\ 

\ 

' 

EXPLANATION 

0 Major topaz deposit 

Topaz occurrence 

X Topaz-bearing rhyolite 

24' F--------' \. .. _ .... 0 500 MILES 

0 500 KILOMETRES 

22' 

FIGURE 10.-Locations of major topaz deposits, topaz occurrences, and topaz-bearing rhyolites in the United States. 

32' 

30' 

28' 

26' 

24' 

22' 

1'\:) 

0 

0 

t"ri 

0 

t'"" 

c 

0 

....::: 

> z 

t::l 

~ 

t"ri 

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0 

e 

~ 

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t"ri 

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0 

'"rj 

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t'"" 

e 

0 

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t"ri 
28° 

.. ----- rv·\ ----,-- I I 

I ~------ I I 

I I -------- II I L 

" 'o / \, ___ l ___ -------1--, L~-·~--~ jl.usabl•~ J ~ )\ \ 1< £> ,_ 

~ ---~-----_] N I I I I T A ·ne"i\\e --< I '; \ M o N ' ' " A I" o "' " o ' '" "\ • ' NN " o 11/h Mtn~"15~y \ 

I ) I ~ 'I I I \rel1'b\eV 1\ f I \ (., I - ... ( I I 

1 

I~;:W .~ I I l - ... , r----------j '- ~~~;~~\·, ORJi:GoN 

II ~ '- \ 'v;----- \. "lw IS C 0 N SIN • R \ -~k. I D J,y. -----1 l '- V.J 'I OR ~.tt~!\~v" 8 ~--~ov "" d' . I : A "0 ,,.,. "' \'' ,, Phosphoria I """ H 0 ' "'" I ' -, ' -H N rdt,Q."")!·, ' C.·ilf''; h·"" • "'" • t "'''" . 

0 "•na V; --,l!!r!ct , '' ~ . Forma,;0 . '--------J, --~. "''"0...'>-_ ' \<S "''" 

€ Sta,'Hi!Js T----- \ I •I' "'>o M >N " t-"---In~·~·· ~aquqketa Shale area.;.,_ -- _, apatl 'N! 0 scrub oa f'rlerv-F;~ -y-----J!J11 1 8 ..... .,..,__~ ~- _ - n1s'~l-~rn'n~ Nr:w 

Prospe sk I ,~ I ' I o w A )' , - I ~~ E\d apatlt l Jr:w-""" 

Pros~eJoe,'• lac cr > " ' 1 ' an •• "' -'' : 8arth1rnine .J~ _ I NEBRAsKA ~ ),- \ '\ 

0 

a 1 ~ ct Mod •- ____ ,___ ' oC ',___, ~ ~A~~~,-"" F'-..~. Jel,\ 

l~ "" , ~<w~<R~' (, NE~·-4 ar,eltirn;n~ f Ll \.-------yiLLINoisi\INlliANAI ~Es'f",r/ 7_ • ... D .4 I ' l ... ~ 'IN tP>y \ U T .4 li I ----------..., \ 1-v- lVI Rl• • r 

"7 \ I I I ( ' " ( SitS j '-....-.J',/ I 

.c,. ,¢, 

0 

'[; 

·t 

' I I I Kentucky "brown rock d'po ~ \ I l \ I .fro S . I co L oR A D o I K A N s A s I M I s s o IT R I (. I -r-;·•J /___,...r:; I. R l t N I ~- ' I 0 Prmgs I I I • ' u.r EN T 1.1 c K 'I ~ ·~ R_~C-- \\ /L _______ J r l<qn Mounta>n • ~-·· s' 'Roseland_'ll'd PJ-; - " 

-+-------- l -l Nelsonlte..J____ ,- cAROL t \ f-/ I --~ ------------I---------;-, ,d-ositst, SEE ,,..f'NoR'fH 

\' / ;----~ Tenness••\"brown rock ~ep ., " '' J--(·--·,--, 

\. t' I' 1 oKLAHoMA 1 • • f ___ ~- _.,.\- -, , so1.1 TH A ) I' ARizoN I IARKANSA~,- I '-....cAROLlN 

.4 ' N E w . 1 

1 I r~ 1 1 k'" q_rea I M E X I C 0 1 '._, f I "land rOC \ -- I, / I "'-v'l....."-l.~--...-~~-J. ' C~arleston \ G EUR(; I A -. 

T, ' I ' _J M I:,; s I s-1 ALABAMA' 

-., t' I r---- < SIPPI I ~~- a distriCt , / I •. . IS th Carq •n '-......._, __ 1 ~--1..------~ ',Norther(\ ~eorsg'a\h~~n Geor~a Field"' . - --J ' N thern Fronda- ou ---- ~---er\,; 

,. 

7 

QIJ '\ TExAs or 1 L--~ 1 "c::. '-\ 11 LOIIISIANA_ ,~ ' Brooks Range, Alaska ox 

', , .... -, -..__,. ', 

\ 

\ Florida land-pebble district 

l 

' \.. ___ 0 500 MILES 

.... ~ .. ,~~· 0 400M 

f-----1--J 0 500 KILOMETRES 

0 400 K 

FIGURE I I.-Locations of phosphate rock and other fluorapatite deposits in the United States. 

EXPLANATION 

Phosphate deposits 

Active mining areas 

Other occurrences 

Fluorapatite deposits 

46° 

44° 

42° 

40° 

36° 

34° 

32° 

30° 

28° 

26° 

24° 

22° 

0 

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..., 

s 

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...... 
22 GEOLOGY AND RESOURCES OF FLUORINE 

siderite, pyrite, sphalerite, galena, and chalcopyrite. The 

pegmatite lies within porphyritic granite intrusive into 

gneiss. The deposit, mined out in 1963 after about 100 

years of production, yielded about 17,000 metric tons of 

cryolite annually prior to 1930 (Lindgren, 1933a, p. 765 ), 

averaged almost 30,000 metric tons annually during 

1935...:38 and more than 50,000 metric tons annually during 

1940-44 (Mudd, 1949, p. 401). It produced about 50,000 

metric tons between 1949 and 1956 (Grogan, 1960, p. 381). 

Some lacustrine brines and evaporites contain concentrations of fluorine; the best examples are the brines and 

recent evaporites of lakes in the rift valleys of Africa where 

lake waters contain as much as I ,625 ppm F. The evaporite 

sequence of Lake Magadi, Kenya, composed largely of 

trona, locally contains as much as 22 percent villiaumite, 

and fluorite is common throughout much of the sequence 

(Sheppard and Gude, 1969, p. D73). 

Fluorite is common in the belt of Lower Carboniferous 

limestones and dolomites at the southwest margin of the 

Donets basin, U.S.S.R., occurring generally as fracture 

fillings in siliceous limestones (Panov, 1962). The fluorite 

is thought to be diagenetic and associated in origin with 

some of the carbonates. The fluorite occurs as cubes 

associated with quartz and pyrite crystals. It is mostly dark 

purple or pinkish, and some is pale violet, green, colorless, 

or black. Also, Abramovich and Nechayev (1960) noted 

possible economic concentrations of fluorine in Permian 

marine carbonates and evaporites west of the Urals in the 

U.S.S.R. Fluorite occurs as a fine dissemination and as 

crystalline aggregates in vugs in dolomitized limestone. 

The CaF2 content of some zones exceeds 30 percent. 

Kazakov and Sokol ova ( 1950) noted that fluorite in marine 

carbonates of the U.S.S.R. is related to the saline facies of 

relict basins, mainly to dolomite, dolomitized limestones, 

phosphate, gypsum, redrocks, anhydrite, potassium and 

magnesium salts, and celestite. 

A minor occMrrence in Permian dolomitic limestones of 

Wyoming contains 12--'15 percent CaF2• 

Carbonatite complexes are notably enriched in fluorine 

mostly dispersed through the rock in silicates, apatite, and 

bastnaesite. Deposits at Okorusu, South-West Africa, and 

at Amba Dongar, India, are economic fluorine deposits 

consisting of fluorite-bearing contact zones and late-stage 

hydrothermal veins (Deans and others, 1972). Apatitebearing carbonatite-the principal source of phosphate in 

southern and eastern Africa-contains 1 ...:3 percent 

fluorine, and considerable reserves are known (Deans, 

1966, p. 393). Apatite-bearing carbonatite rock near 

Jacupiranga, Sao Paulo, Brazil, being mined for 

phosphate, contains 4-5 percent fluorine (Abreu, 1960, p. 

123 ), and apatite-bearing carbonatite rocks in the U.S.S.R. 

are a present source of fluorine, recovered as a byproduct of 

fertilizer production. Carbonatite at Mountain Pass, 

Calif., contains at least 1 percent fluorine, mostly in 

bastnaesite (Olson and others, 1954); about 1,000,000 tons 

of fluorine exists as a potential byproduct of rare-earth 

extraction at Mountain Pass. 

Fluorspar deposits in unconsolidated tuffs near Rome, 

Italy, are lenses composed of finely crystalline fluorite, 

barite, calcite, dolomite, apatite, opal, and chalcedonic 

quartz with minor amounts of detrital minerals and 

volcanic glass. Fluorite content of some zones averages 55 

percent. These lenses are thought to be chemical sedimentary deposits formed in lake basins by hydrothermal 

fluids rich in fluorine, calcium, barium, strontium, 

silicon, sulfur, and phosphorus (Spada, 1969). 

TECTONIC SETTING OF FLUORINE 

DEPOSITS 

By D. R. SHAWE 

Distribution of fluorine mineral deposits in the United 

States has been strongly controlled by tectonic environment. Regions containing fluorine mineral deposits are 

geologic provinces generally characterized by many faults 

and intrusive igneous rocks. This generalization applies 

to virtually all types of fluorine occurrences, with the 

notable exception of those deposits formed during sedimentation, particularly the sedimentary phosphate 

deposits. Some geophysical parameters broadly reflect the 

tectonic composition of the United States and thus outline 

regions of known or expected fluorine deposits. 

RELATION OF FLUORINE DEPOSITS TO FAULTS 

Areas of fluorine mineral deposits are near major faults 

in the United States (fig. 12). Faults in figure 12 are somewhat generalized and some of them represent major zones 

of faults. 

Practically all fluorspar deposits-the dominant type 

of epigenetic fluorine mineral deposits-are closely 

associated with faults, especially in areas of tension along 

the margins of uplifts or structural basins (Van Alstine, 

1954). Many deposits occur as veins along faults or as . 

replacement deposits in fractured rocks close to faults. The 

dominant orientations of regional faults that have 

controlled fluorspar deposits are northwesterly, northeasterly, and easterly. 

Fluorspar deposits are associated with both strike-slip 

faults and tensional, normal faults such as the northtrending faults in the Basin-Range province of the 

Western United States. Indeed, the distribution of fluorine 

mineral deposits in the Western United States closely 

follows that of Basin-Range structure (fig. 13). For 

example, the Rio Grande trough in New Mexico and its 

projection northward through Colorado has localized 

fluorspar deposits. Also, in southwestern New Mexico, 

fluorspar deposits in places occur in Basin-Range faults 

(Elston, 1970, p. 147, 150). On the other hand, fluorspar 

deposits in the Eastern United States are related generally 

to zones of strike-slip, not tensional, faults. 
48 • '"o ' "v lL'+ 122· 120· 118 · 116• 114• 112 • 110· toa· 105• 104• 102· too• ga· gs• 94• 92• go• sa · 86. s4• 82 . so" 78" 76. 74 • 72• 7o• bH. bb. b4. 48 • 

46° 

44. 

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42. 

38. 

36• 

34° 

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;N 0 R T H 

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' \ l 

' '--- 0 500 MILES 

0 500 KI LOMETRES 

46' 

44 ' 

42 ' 

40 ' 

38' 

36' 

34 ' 

28' 

.•• :IP-"·· 

FIGURE 12.-Major faults (heavy lines) and distribution of fluorine minerals (shaded) in the United States: fluorite. topaz, and fluorapatite (excluding sedimentary phosphorite). 

Thin lines are alinements of major elongate clusters (belts) of fluorite deposits. 

...., 

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L O U I S I ANA 1 

' 

\" \ 

' '--- 0 500 MILES 

0 500 KILOMETR ES 

.•• ;IP-~·· 

' 

78 ' 76' 74' 

FIGURE 13.-Normal faults (heavy lines; after Gilluly, 1963, and other sources), and distribution (shaded) of fluorine mineral deposits in the Western United States. 

4 6' 

4 4 ' 

42' 

40' 

34' 

32' 

28' 

26 ' 

24 ' 

22 ' 

)'.:) 

..,. 

0 

t'<j 

0 

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TECTONIC SETTING OF FLUORINE DEPOSITS 25 

Figure 12 shows that a number of major faults have no 

known fluorine mineral deposits associated with them, for 

example the San Andreas strike-slip fault zone along the 

Pacific Coast of California. 

Fluorspar deposits tend to occur in elongate clusters 

that form alined zones or belts (fig. 12; Worl, Van Alstine, 

and Heyl, 1974). Northwesterly and northeasterly alinements dominate. Some northerly alinements are evident in 

Nevada and Colorado and some easterly alinements show 

up in southern Arizona, in the Missouri-Illinois-Kentucky 

area, and in the northeastern United States. In places the 

alinements of fluorspar deposits nearly coincide with 

major faults even though individual deposits may not 

actually occur in the major faults themselves. 

In the Eastern United States dominant northeasterly 

alinements of fluorspar belts reflect the dominant northeasterly structural grain of the region. 

In the Western United States in the Basin-Range 

province, however, fluorspar belts aline northwesterly and 

northeasterly but structural grain alines northerly. Some 

pre-Basin-Range faults are oriented northwesterly and 

northeasterly, have been deformed by strike-slip movement (for example, Shawe, 1965, p. 1372-1375), and are 

reflected by alinement of the fluorspar belts. 

RELATION OF FLUORINE DEPOSITS TO 

INTRUSIVE IGNEOUS ROCKS 

The general coincidence of epigenetic fluorine mineral 

deposits and intrusive rocks in the United States is shown 

in figure 14. In some large areas in which fluorine deposits occur no intrusive rocks are shown in the figure; 

numerous intrusives are known in these areas but are too 

small to be shown at the scale of the map. For example, 

many small mafic intrusives rocks are present in the 

Illinois-Kentucky district; intrusives are present at Magnet 

Cove, central Arkansas; and Precambrian intrusives (not 

depicted in fig. 14) have numerous associated fluorine 

mineral occurrences in central Texas and in central 

Colorado. 

On the basis of rather incomplete data the ages of the 

fluorine mineral deposits correlate with the ages of the 

intrusive rocks with which they are associated. Fluoriteand topaz-bearing greisens and pegmatites were formed 

during the igneous cycle of the Pikes Peak Granite of 

central Colorado and of the granite in the Llano uplift of 

central Texas, both of Precambrian Y age (800-1,600 

m.y.-million years). The ages of fluorine-bearing 

greisens and pegmatites agree with those of their 

associated Paleozoic granitic rocks in the Eastern United 

States (fig. 14). Skarn or contact metamorphic deposits 

contammg fluorine-bearing minerals are clearly 

associated with specific plutons of Paleozoic age in the 

Eastern United States and of Mesozoic and Cenozoic age in 

the Western United States. These deposits were formed 

either at the time of emplacement of the plutons or shortly 

thereafter as a late stage phenomenon of the igneous 

episode, and hence are certainly of nearly the same age as 

the intrusive rocks. Many fluorine mineral deposits in the 

Western United States in Tertiary volcanic rocks or near 

Tertiary intrusive rocks can be dated by geologic relations 

as Tertiary in age (R. G. Worl, written commun., 1972). 

The dated deposits are all younger than 32 m.y. and none 

of these are demonstrably younger than 6 m.y., with the 

exception of a few hot-springs apron deposits such as that 

at Ojo Caliente, N. Mex., that currently are being 

deposited. 

The age distribution of these 6-32 m.y. (Tertiary) 

deposits does not coincide, however, with the age distribution of the times of transition from andesitic to fundamentally basaltic volcanism in the Western United States 

shown by Christiansen and Lipman (1972, fig. 5). Their 

data suggest successively younger ages from western Texas 

northward and westward, but Worl (written commun., 

1973) shows fluorspar deposits of widely differing ages 

randomly distributed in the Western United States. The 

deposits thus clearly are not related to the beginning of the 

episode of basaltic-rhyolitic (bimodal) volcanism, but may 

have formed locally any time thereafter. In fact, some 

fluorspar deposits are related to alkalic rocks formed 

during earlier predominantly andesitic volcanism. 

Strong evidence suggests that Tertiary deposits are 

related genetically in some places to inferred intrusive 

rocks even though the deposits are associated spatially 

with extrusive rocks. At Spor Mountain, Utah, for 

example, Staatz and Osterwald (1959, p. 59-61) demonstrated the likelihood of fluorine-rich intrusives at depth, 

similar in composition to the widespread topaz-bearing 

rhyolites at the surface near Spor Mountain, and showed 

that such intrusives were the likely sources of the fluorine 

in the fluorspar deposits. 

At Climax, Colo., fluorite and topaz were deposited 

with molybdenite in several successive episodes each 

related to intrusion of an alkalic-silicic porphyry stock of 

middle Tertiary age (Wallace and others, 1968). 

Fluorine-rich igneous rocks form two well-defined 

provinces-one in the Eastern United States and one in the 

Western United States (fig. 8)-that roughly accord with 

areas of intrusive rocks outlined on figure 14, but there are 

important variations in the distributions. For example, 

Tertiary intrusive rocks are distributed in a broad belt 

through the Western United States, but they are enriched 

in fluorine only in parts of the broad belt, and these parts 

generally coincide with areas of fluorine mineral deposits. 

The absence of fluorine-rich rocks in north-central 

Washington State shown in figure 8, despite the presence 

of fluorine mineral deposits (fig. 14), is thought to reflect 

lack of data rather than a rea.! absence of such rocks in the 

area. The striking coincidence overall of the areas of 

fluorine-rich igneous rocks with areas of epigenetic 

fluorine mineral deposits (compare fig. 8 with fig. 14) 
48 c-~,2~a~--~r2 --~'r4~--~'r2~2· __ ~'+~o_~'+'~a· __ ~,+'~G· __ ~,+'4~--~''r2~·--~''ro~· __ ,,o~a ~~o~6 ~'ro4 --~'or2~·--',oo~·-- --~ --~4' ___ --~•To --~ra_· __ ~ar6' __ ~s;4~--~a~2 --~aTo --~7 · __ ' __ ~7~4· __ ' __ · __ ~o~--~u~~~;"~ 

46 ' 

44 ' 

3"40 

32' 

30' 

114 . 

t')' oM l Nc 

I 

,_ -~---

/ 

I 

I 

X I C O 

... ,: .. J>. i '-~-..1..--J ~· .. •/ ·---~\[:--~ 

'\ · .. l . --, '-, ' 

DAKOTA I 

I 

1 0KLAH0~1A 

I 

~-' 

TEXAS 

Q 

'""-....••:- ' - \ 

\,., 

' ' "--, 0 500 MILES 

0 500 KILOMETRES 

EXPLANATION 

I• \ ·.j Granitic and other intrusive rocks of Tertiary age 

B 

... Granitic rocks of 

Mesozoic age 

~ Granitic rocks of 

Paleozoic age 

c:::J Area of fluorine mineral 

deposits 

FIGURE 14.-Major Phanerozoic intrusive bodies (£rom King, 1967) and distribution of epigenetic fluorine minerals in the United States. 

74' 

44' 

42' 

40' 

34' 

28' 

1-.:l 

0'> 

0 

M 

0 

t"" 

0 

0 

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> z 

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c::: 

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CJ 

M 

CJl 

0 

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'Tj 

t"" 

c::: 

0 

:;tl 

z 

M 
TECTONIC SETTING OF FLUORINE DEPOSITS 27 

indicates a likely genetic relation between such igneous 

rocks and mineral deposits. In a number of places 

fluorine-rich igneous rocks are related genetically to the 

associated fluorine mineral deposits. This is true of the 

Pikes Peak Granite, Colorado, and associated topaz and 

greisen fluorspar deposits; the granite of the Llano uplift, 

Texas, and associated fluorine mineral deposits; a number 

of plutons in the Eastern United States and their associated 

greisen and pegmatite deposits; tin granites and associated 

fluorspar deposits at Lost River, Alaska; and the Climax, 

Colo., stocks and associated topaz- and fluorite-bearing 

molybdenite deposits. In other places well-based inference 

suggests a genetic relation, as in the Illinois-Kentucky 

district where fluorspar is spatially associated with 

fluorine-rich mafic alkalic rocks, at Magnet Cove, Ark., 

where fluorspar is spatially associated with fluorine-rich 

alkalic rocks, and at Spor Mountain, Utah, and the 

southern Wah Wah Mountains, Utah, where fluorspar 

deposits are spatially associated with topaz-bearing 

rhyolites and their inferred intrusive equivalents. 

The tendency for intrusive rocks of special chemical 

composition to correlate with fluorine mineral deposits is 

illustrated in another way. The quartz diorite line of 

Moore (1959), which marks the western margin of 

potassium-enriched intrusive rocks in the Western United 

States (fig. 14), forms an approximate western boundary of 

the areas of fluorine mineral deposits. Perhaps the higher 

potassium content of intrusive rocks east of the quartz 

diorite line correlates partly with a higher fluorine content 

of the rocks in this region. 

RELATION OF FLUORINE DEPOSITS TO 

GEOPHYSICAL PROPERTIES 

Figure 15 shows Bouguer gravity data for the United 

States in relation to the distribution of fluorine mineral 

deposits. Low-gravity regions, highlighted on the map, in 

a general way represent zones in the lithosphere-in the 

crust and possibly also in the upper mantle-where rocks 

are more silicic and hence lighter than in surrounding 

areas. These regions broadly represent crustal zones 

intruded by significant volumes of silicic igneous rocks. 

The low-gravity contours also roughly outline topographically high regions-the mountainous parts of the 

country-that have risen isostatically in response to their 

low density. These low-gravity regions roughly correlate 

with areas of fluorine mineral deposits, but the correlation 

is imperfect or lacking in wide areas. Most significant is 

the absence of a low-gravity zone in the vicinity of the 

important Illinois-Kentucky fluorspar district. On the 

other hand, an area of fluorine deposits in north-central 

Washington State nearly coincides with a low-gravity 

zone; west- and east-trending lobes of fluorine mineral 

occurrences in western and central Montana coincide with 

similarly trending low-gravity lobes; the important zone 

of fluorine mineral deposits extending northward 

through central Colorado nearly coincides with a major 

gravity low; a string of fluorine mineral occurrences 

extending from eastern Kansas northeastward through 

Wisconsin lies along a northeasterly oriented gravity low; 

and fluorine mineral occurrences in northwestern Ohio 

are clustered on a gravity low. 

Moore (1962) suggested a correlation between high 

potassium content of Cenozoic igneous rocks and low 

Bouguer gravity values in the Western United States. 

Heat-flow values in the Western United States reported 

by Blackwell ( 1971, fig. 2) are relatively high and generally 

exceed 2 x 10-6 cal/cm2/sec in broad regions that coincide 

remarkably with the distribution of fluorite deposits in 

this part of the country (fig. 16). Comparison of figure 16 

with figure 8 also shows a striking coincidence in the 

distribution of high heat-flow values and the distribution 

of fluorine-rich igneous rocks in the Western United 

States. (Again, if fluorine-rich rocks are present in 

northern Washington, a condition unknown for lack of 

data, the correlation would be improved.) On the other 

hand, comparison of the heat-flow data with the distribution of Tertiary intrusive rocks in the Western United 

States (fig. 14) shows a generally poor correlation; 

numerous Tertiary intrusives occur in western Oregon 

and Washington, in central Montana, in western 

Wyoming, and in southeastern Utah where heat-flow 

values appear to be low and no fluorine mineral deposits 

are known. 

Present heat flow (fig. 16) may be different from that in 

the middle to late Tertiary when fluorine mineral deposits 

and fluorine-rich igneous rocks were forming. However, 

some of the fluorine-rich volcanic rocks are as young as 3 

m.y. (Armstrong, 1970, table 3, p. 210-211), and the 

occurrence of fluorite in modem hot-springs aprons at 

Ojo Caliente, N. Mex., and elsewhere, indicates that the 

episode of fluorine mobility likely extends from the 

Tertiary into the Holocene. Probably the episode of 

fluorine-rich magmatism and fluorine mineral deposition 

that commenced about 30 m.y. ago (middle Tertiary) in 

the Western United States is still manifested by high heat 

flow throughout the region of that magmatism and 

mineralization. 

Where regional aeromagnetic data are available, some 

correlations between magnetic anomalies and the 

distribution of fluorite deposits are apparent. For 

example, in Colorado the positions of elongate zones 

(alinements) of numerous sharp positive aeromagnetic 

anomalies (Zietz and Kirby, 1972) nearly coincide with the 

positions of fluorite mineral belts (fig. 16) and are inferred 

to represent in part zones of buried intrusive rocks. 

On a global scale, residual magnetic contours based on 

data taken by U.S.S.R. satellite Cosmos 49 at altitudes of 

155-310 miles (250-500 km) (Zietz and others, 1970, fig. 3) 

show pronounced northeasterly and northwesterly 

orientations across much of the United States, reflecting 
48 • 12a · 125• 124 • 122 ° 120° 11a · 116 · 114 • 112 ° 110· 10s· to6 " 104 • 102 · wo· gg • gs· 94 ° 92 ° go · as· a6o 94 • 82 ° so · 78 ° 75• 74 • 12 • 70° 68 " 66. 54 • 48

• 

46" 

44 " 

42" 

32 ' 

30 ' 

EXPLANATION 

D Gravity <-50 milligals 

t\: .. J Gravity < -150milligals 

[·\·;:\( ~·.j Gravity <-250 milligals 

[:;SS3 Area of fluorine mineral 

deposits 

114° 

' \ 

' \ 

' ' \., __ 

I 

r----

ll 0 M A \ / < 

l]:AI 'AKSAS 1 ENN'N':~~ :.-<\ ,.----,-- ~~ ~-~ ~ { I 

"-l, ,' : r-------1 

I ~ S 1

SSIS- 1' PI :A ~ L" 

, / I 

\ : 

LOU iS'lA-N;.( A.~ 

0 500 MILES 

0 500 KILOM ETRES ... ;;~'-" 

so· 

FIGURE 15.-Bouguer gravity (after Woollard and Joesting, 1964) and distribution of fluorine mineral deposits in the United States. 

46 ' 

44 ' 

28' 

22' 

78" 76' 74 " 

1':) 

00 

0 

M 

0 

['"' 

0 

0 

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z 

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(') 

t'l'1 

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c:: 

0 

::0 

z 

t'l'1 
40' 

28' 

No data ORE:r;ON 

I"\ -----1----------~--: '-____,..-.. ""~''-- , I 

I \ ESOTA N 0 R T H D A K 0 T A\ M I N N ' • I I 

I \ ;------------t I 

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r"-'-.... , 

\ 

TEXAS 

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\ 

' ' '---.... 0 500 MILES 

0 500 Kl LOM ETRES 

74' 72' 700 6SO 66' 64' 

44' 

40' 

38' 

34' 

32' 

30' 

28' 

26' 

24' 

22' 

FIGURE 16.-Fluorite mineral belts (heavy lines) and regions (stippled) in the Western United States with heat-flow values generally greater than 2.0XI0-6 cal/cm2/sec (based on 

Blackwell, 1971, fig. 2). Thin lines in Colorado show alinements of numerous sharp positive aeromagnetic anomalies (based on Zietz and Kirby, 1972) that in part may represent zones of buried intrusive rocks. 

..., 

t"r1 

q 

0 

z 

n 

1JJ 

t"r1 

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..., 

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30 GEOLOGY AND RESOURCES OF FLUORINE 

the dominance of. these directions in gross crustal 

structure. 

Earthquake epicenters in the United States reported 

through 1964 and shown by Woollard (1969, fig. 1) are 

characteristically disposed in elongate clusters that trend 

dominantly northeasterly and northwesterly. The earthquakes undoubtedly are related to zones of active faulting 

which reflect a fundamental structural framework of the 

continent. Some of the northeasterly and northwesterly 

zones of seismic activity coincide with fluorite mineral 

belts, substantiating the conclusion that the mineral belts 

are in part related to major fault zones. The fault zones no 

doubt are of considerable age and some must reflect part of 

the Precambrian as well as Phanerozoic structural grain. 

Crustal thickness and mean crustal seismic velocity 

show little relation to the distribution of fluorine mineral 

deposits (fig. 17). For example, crustal thickness varies 

from more than 30 miles (50 km) to less than 20 miles 

(30 km) in less than 60 miles (100 km) horizontally within 

the fluorine province in eastern California and western 

Nevada, and crustal thickness ranges from slightly more 

than 30 miles (50 km) to less than 20 miles (30 km) from 

Colorado through New Mexico and into southern Arizona without commensurate change in the general 

character of fluorine mineral deposits in these regions. 

Mean crustal seismic velocity, which reflects primarily 

crustal composition and to a lesser degree structural 

complexity, also shows no correlation with the distribution of fluorine mineral deposits. Apparently the formation of fluorine deposits is not closely related to any crustal 

properties that influence crustal thickness and seismic 

velocity. 

A broad region of low(<8 km/sec) upper-mantle seismic 

velocity is present in the Western United States and this 

region quite closely encompasses the region of middle to 

late Tertiary volcanism and fluorine mineralization (fig. 

17). The region of low velocity in the upper mantle likely 

is characterized by above-normal temperatures, and this 

condition generally accords with the high heat flow of the 

overlying crust(fig. 15). Woollard (1968) proposed that the 

region of low seismic velocity in the upper mantle may 

reflect a phase transition from normal mantle material of 

dunite composition, high seismic velocity, and density 

=3.35, into mantle material of eclogite composition, lower 

seismic velocity, and higher density. The compositional 

change resulting from the phase transition suggested by 

Woollard may have involved fractionation of materials 

from the upper mantle into the overlying crust, and this 

event may have taken place in the recent geologic past, 

from middle Tertiary time onward. Possibly these 

materials included high-fluorine basaltic and rhyolitic 

magmas and fluorine-rich fluids that penetrated upward 

toward the surface of the crust, to account for the fluorinerich igneous rocks and fluorine mineral deposits of middle 

Tertiary and younger age in the province. On the other 

hand, the magmatism and fluorine mineralization may 

have been phenomena originating within the crust, but in 

response to high heat flow from the mantle and to related 

processes. In any case, the spatial coincidence of the region 

of low upper-mantle velocity with a region of high heat 

flow, middle to late Tertiary fluorine-rich magmatism, 

and middle to late Tertiary fluorine mineralization indicates a strong mantle control on the magmatism and 

fluorine mineralization. 

DESCRIPTIONS OF MAJOR FLUORINE 

DEPOSITS AND DISTRICTS AND 

IMPORTANT TYPES OF FLUORINE 

OCCURRENCES 

Fluorine deposits are discussed in following pages in 

geographic groups characterized to some degree by 

common form, association, mineralogy, and geologic 

environment. Some deposits do not fit naturally into a 

classification based on geographic distribution but nevertheless are included in the geographic groups for 

convenience of discussion. The geographic divisions used 

are as follows: Alaska; Washington-Idaho-MontanaWyoming-South Dakota; Nevada-Utah-southeastern 

California-western Arizona; Colorado-New Mexicowestern Texas-southeastern Arizona; and Eastern and 

Central United States (including the Illinois-Kentucky 

district). Of course not all types of fluorine deposits are 

present in each geographic group. Within the geographic 

groups, deposits are described State by State where 

appropriate. Fluorine-bearing phosphate deposits of the 

conterminous United States are discussed as an additional 

group because of their unique character. 

ALASKA 

By C. L. SAINSBURY 

Fluorine has not been produced commercially in 

Alaska, although fluorite is reported at many localities 

(Cobb, 1964; Worl, Van Alstine and Heyl, 1974). Topaz 

and fluorine-bearing phosphate rock are also known at 

several localities. The largest known deposits of 

fluorite-at Lost River, Seward Peninsula-were drilled 

extensively in 1972, and large reserves of fluorite (several 

million tons of contained CaF 2-) associated with minerals 

of tin, tungsten, beryllium and base metals had already 

been announced (Northern Miner, Toronto, Oct. 1, 1970). 

These deposits are described in detail in this report; other 

deposits of smaller proved economic potential are 

described only briefly. 

DESCRIPTIONS OF INDIVIDUAL DISTRICTS AND DEPOSITS 

LOST RIVER 

Fluorspar deposits at Lost River on the Seward 

Peninsula constitute the largest known fluorine potential 

in Alaska; the main deposits are located at lat 65°28' N.; 
48 c- 2~a~--~'r26~·--~'r24~·--~'r2~2· __ ~,T2~o '~a· __ ~'T'6~--~'T'4 --~'r' --~'o~·--~'ora~· o~6 ~'To~4-~'or2~·--~~oo · __ ,9a~· ___ --~gr4_· __ ,9r2· ___ 9,o~--~ --~ar6 · __ ,a4r· ___ a,2~·-- a,o --~-7Ta~·--~7T6~·--~ · __ · __ · __ ~~,~~--~~~r---~~~~A 

46 

44 

42" 

> 6.5 km/sec } 

6.2-6.5 km/sec Mean crustal seismic 

< 6.2 km/sec 

Contour of crustal thickness- Interval 10 km 

Contour of upper-mantle 

seismic velocity -

Hachures toward velocity < 8 km/sec 

velocity 

[: ::·:·: ·:-j Area of fluorine mineral 

deposits 

I \ 

-I ~lr''l::l.l;_:>A"i?:P'"W""~T"">o · ~, "[kt 

} ~· .. i~ 

0 500 MILES 

0 500 KilOMETRES 

46" 

44 " 

42" 

40" 

38" 

36" 

34" 

32" 

26" 

24" 

22" 

FIGURE 17.--Crustal thickness and mean crustal seismic velocity (from Pakiser and Zietz, 1965, fig: 2), upper-mantle seismic velocity (from Herrin and Taggart, 1962), and distribution of fluorine mineral deposits in the United States. 

> t"' 

> [J) 

~ 

(.X) 
32 GEOLOGY AND RESOURCES OF FLUORINE 

long 167°10' W. Although the main proved reserves are in 

and near the Lost River tin mine, other deposits of 

unassessed potential crop out discontinuously along the 

Rapid River thrust fault for a distance of several miles 

westward from the mine area. 

Although the Lost River tin deposits were found in 

1903, the beryllium-bearing fluorite lodes were found 

much later, in 1961-64, during a detailed geologic 

mapping program by the U.S. Geological Survey (Sainsbury, 1969). 

No fluorite was produced during the mining of tin ores 

(1913-14 and 1949-55) from the Lost River mine, although 

much fluorite passed through the mill. Lost River has the 

potential of supplying a significant fraction of total 

United States fluorite production. 

The main fluorite-bearing deposits in the Lost River 

area are almost entirely replacement bodies in limestone 

and argillaceous limestone of Early to Middle Ordovician 

age, which aggregate at least 8,000 feet (2,400 m), and 

possibly 12,000 feet (3, 700 m) in thickness. The Lower 

Ordovician limestones are divided into two units, a lower 

shallow-water facies of thin-bedded argillaceous limestone with minor interbeds of thick-bedded limestone, 

possibly 4,500 feet (1,400 m) thick, and an upper quietwater facies of medium- to thick-bedded limestone with 

interbeds of thin-bedded argillaceous limestone, about 

6,500 feet (2,000m) thick. Most of the known fluorite 

deposits are in rocks of these units although one deposit is 

within dolomitized limestone, below a thin black shale 

about 50 feet ( 15 m) thick, which is of early Middle Ordovician age. All these rocks are thrust-faulted in a major 

thrust province, and most ore bodies are localized in 

shattered dolomitized limestone and limestone beneath 

thrust faults, or in limestones near or above granite 

plutons. 

Two main types of large deposits are known within the 

district, tin-poor stockworks and tin-rich stockworks. The 

larger (tin-poor) of these consists of replacement veins, 

veinlets, small pipes, and tabular replacement bodies in 

limestone and along the walls of lamprophyre dikes, all of 

which are localized near or within shattered rocks beneath 

thrust faults (for more detailed information on the several 

known deposits of this type see Sainsbury, 1969, p. 64-84). 

The principal tin-poor deposit (Camp Creek) adjoins the 

tin deposits at Lost River mine, and was explored by 

diamond-drill holes in 1964 by the U.S. Bureau of Mines 

(J. J. Mulligan, unpub. data, 1964 ; Mulligan 

presented some diamond-drill sampling data on the 

fluorite-beryllium deposits in the Lost River valley; Sainsbury, 1965), and by P.C.E. Explorations, Ltd., who proved 

an extension of the deposit by diamond drilling in 

1970-72. This deposit extends for almost 4,000 feet (1,200 

m) along the shattered zone beneath the Rapid River and 

Camp Creek thrust faults and raggedly downdip beneath 

the thrusts for several hundred feet. The deposit is best 

classed as a stockwork which must be mined on a large 

scale with assay boundaries-ore reserves appear sufficient 

to satisfy a large-tonnage operation for several years 

(Northern Miner, Toronto, Oct. 1, 1970). 

Beryllium is the most important associate of fluorite in 

the Camp Creek and similar deposits along the Rapid 

River fault, and tin is almost lacking. Four other areas, 

each several thousand feet long, contain stockworks of 

fluorite-beryllium veinlets and occur along the west 

extension of the Rapid River fault. The westernmost area, 

some 7 miles (11 km) west of Lost River mine, was drilled 

in 1962 by N ewmont Mining Co.; this drilling showed that 

the mineralized zone dipped shallowly south beneath a 

small thrust which underlies the Rapid River fault. The 

mineralogy of the ores is similar to that of Camp Creek, 

described in the next paragraph, and tin-bearing sulfide 

ores were intersected in the deeper drill holes (Peter 0. 

Sandvik, oral commun., 1963). 

In the Camp Creek deposit, fluorite occurs as finegrained intergrowths and interlayers with diaspore, tourmaline, white mica, and small amounts of the beryllium 

minerals chrysoberyl and euclase. The general mineralogy of the veins and veinlets in this type of deposit is as 

follows, in volume percent: fluorite, 45-65; diaspore, 5-15; 

tourmaline, 0-10; chrysoberyl, 3-10; white mica, 0-5; and 

small to variable amounts of todorokite1, hematite and 

euclase, as well a~ trace amounts of phenakite, bertrandite, 

bityite and cassiterite. These ores typically are layered 

rhythmically on a scale of a millimetre or two, with finer 

layers of fluorite interlayered with fluorite that is accompanied by the minerals named above. The layering is 

parallel to the veinlets, and both veinlets and layers may 

cut obliquely across thin-bedded limestones without offsetting the bedding. Hence, the layers are interpreted as 

replacement "fronts." 

Studies of rocks and ores, as well as of individual 

minerals in the ores, reveal a common suite of trace 

elements such as tin, beryllium, silver, arsenic, lead, zinc, 

boron, lithium, and niobium, and show that the fluoriteberryllium deposits are distributed zonally above and 

around the tin deposits. 

The second main type of deposit (tin-rich) is 

exemplified by the Lost River tin mine, which contains 

fluorite and topaz in close association with the tin ores, as 

well as in a large body of mineralized rock above a buried 

granite in the Cupola area (Sainsbury, 1964b). Fluoriterich selvages along the tin ore shoot, which lies along an 

altered dike that dips steeply into the granite cupola, are as 

much as several feet thick, and contain both tin and 

beryllium minerals in addition to the fluorite. The Cupola 

area is a crudely conical mass of marmorized limestone cut 

both by garnet-bearing skarn bodies, and by an intricate 

I Work by Fred Hildebrand (written commun., 1970) showed that in addition to todorokite, 

pyrolusite and psi lome lane occur in the ores, and that cryptomelane, chalcophanite, and birnes· 

site may occur. 
ALASKA 33 

network of veins and veinlets containing fluorite, 

chrysoberyl, cassiterite, wolframite, topaz, quartz and 

numerous other minerals. Mining of this deposit, which 

contains several millions tons of material, would produce 

fluorite and several valuable byproducts. Ore reserves in 

the Cupola area (number 1 deposit of P.C.E. Explorations, Ltd.) amount to at least 5,974,000 tons of ore grading 

30.80 percent CaF2, 0.30 percent tin, 0.18 percent BeO, and 

recoverable amounts of tungsten and base-metal sulfide 

(Northern Miner, Toronto Oct. 1, 1970). 

Deposits which are transitional between tin lodes and 

bery Ilium lodes occur in Paleozoic limestone around the 

south side of the granite of Tin Creek, about I mile southeasterly from the Camp Creek beryllium lodes. These 

transitional deposits contain fluorite, chrysoberyl, 

cassiterite, manganese oxides, and sulfide minerals. 

Locally, high gold values have been reported in some of 

the oxidized sulfide veins (John Conrow, oral commun., 

1963), a relation which was found to exist at the Rapid 

River beryllium-fluorite deposits (based on samples taken 

in 1970 by the Geological Survey). The ore minerals occur 

in numerous veinlets from a fraction of an inch to a few 

feet thick over an area of about one-half mile square; however, the area has not been drilled and the depth to granite 

is unknown. Hence, although the potential may be large, 

it is unassessed. 

The distinguishing characteristics of the large fluorite 

deposits of the Lost River area are: (I) their association 

with tin deposits that are genetically related to biotite 

granites, (2) their complex mineralogy, which offers valuable byproducts as well as giving difficulty in beneficiation, and (3) their irregular form, which requires assays to 

determine their boundaries. 

The structural location of ore bodies near or above biotite granite stocks, and the alinement of deposits along the 

Rapid River thrust fault, are notable. The great extent of 

mineralized rock along the Rapid River fault also is 

exceptional. 

Studies of trace elements and fluid inclusions, and geologic mapping, show conclusively that the deposits are of 

hydrothermal origin, the fluorine, beryllium, boron, and 

other metallic elements being derived from deeper 

portions of the exposed granites in and around which the 

tin deposits are localized. 

OTHER DEPOSITS 

In addition to its occurrence in the main lodes near Lost 

River, fluorine occurs in fluorite, topaz or other fluorinebearing minerals (idocrase, fluorine-micas) near other tin 

deposits on the Seward Peninsula, in breccia pipes 

cemented by fluorite in the Kigluaik Mountains, in 

scattered deposits of poorly assessed potential where 

alkalic rocks of Cretaceous age intrude carbonate rocks in 

the Darby Mountains, eastern Seward Peninsula, and in 

complex replacement bodies in interstratified marble and 

chloritic schist of Precambrian age north of Nome (Eakin, 

1915; Brobst and others, 1971). Together, the deposits may 

delineate a fluorine-rich province genetically associated 

with silicic igneous intrusives of Cretaceous to Tertiary(?) 

age. Workers in this general area should at least be aware 

of the possibility of undiscovered commercial deposits of 

fluorspar. 

Fluorite occurs in tin deposits near granite stocks at 

Cape Mountain, Brooks Mountain, Black Mountain, and 

Ear Mountain. None of these deposits is large enough to be 

of commercial significance. At Black Mountain, topaz is 

abundant in a small part of the granite that was 

greisenized. Similar greisenized granite at Lost River, 

which contains up to 28 percent topaz, contains almost 8 

percent fluorine, equivalent to about 16 percent CaF2• 

In the Kigluaik Mountains, about 40 miles (65 km) 

north of Nome, fluorite cements breccia in two pipes 

along a tributary of the Tisuk River. The pipes consist of 

angular jasperoid fragments cemented by fluorite. The 

largest measures at least 80 feet (25m) long and 20 feet (6 

m) wide. Tourmalinized granite crops out nearby and elsewhere in the vicinity, suggesting that other pipes may 

exist. 

Fluorite has long been known at scattered localities in a 

limestone area about 20 miles (32 km) north of Nome 

(Eakin, 1915; Herreid, 1966). Trenching has disclosed that 

fluorite accompanies barite in a brecciated and dolomitized marble intercalated in chloritic schist of the Precambrian N orne Group. Anomalous amounts of lead, 

zinc, silver, and gold accompany the fluorite and barite. 

Because other marble beds probably occur beneath the one 

exposed by trenching, fluorite may be found at greater 

depths and may be of economic value (Brobst and others, 

1971 ). Moreover, fluorite may be found beneath some of 

the many gossans known elsewhere in this general region 

(Eakin, 1915 ). 

In the eastern part of the Seward Peninsula, an extensive belt of granitic rocks is accompanied by a varied suite 

of alkalic rocks (Miller, 1971). Fluorite has been noted at 

many localities in this general region (Vivian Velette, oral 

commun., 1968), for instance, in a fine-grained intrusive at 

the southeast end of the Bendeleben Mountains. 

According to Thomas P. Miller (oral commun., 1970), 

fluorite in small amounts is widespread where alkalic 

rocks intrude limestones. According to A. A. Beus (oral 

commun., 1967), large fluorite deposits associated with 

alkalic rocks are known in nearby Siberia. Hence, the geologically similar east part of the Seward Peninsula is 

shown as a possible fluorine-rich province which may 

contain undiscovered fluorite deposits. 

Fluorite in minor amounts is known at many places in 

Alaska outside the Seward Peninsula. The most significant are shown on the map by Worl, Van Alstine, and Heyl 

(1974); in 1973 none were economically important. 

At Bokan Mountain, southeastern Alaska, a peralkalic 

granite and the adjoining rocks contain small amounts of 
34 GEOLOGY AND RESOURCES OF FLUORINE 

fluorite associated with uranium ores, but the individual 

deposits and the total amount of fluorite are small (E. M. 

MacKevett, Jr., oral commun., 1971). 

In Glacier and Groundhog Basins, southeastern Alaska, 

where substantial deposits of lead and zinc are known, 

sulfide-bearing veins have a gangue of quartz and fluorite, 

and a large breccia vein as much as 40 feet ( 12 m) thick contains notable fluorite, as do other quartz veins nearby 

(Gault and others, 1953, p. 23). Large breccia pipes as 

much as 400 feet (120m) in diameter are known in the area. 

They contain some fluorite and topaz, but have not been 

evaluated for fluorite at depth. 

Fluorite in float or bedrock occurs sporadically across 

central and eastern Alaska from the Eagle area to westcentral Alaska, along a belt which contains placer tin 

associated with granitic rocks of Late Cretaceous to 

Tertiary age. No deposits of economic promise are known. 

If lode tin deposits are found fluorite and (or) topaz in 

larger amounts are likely to be associated. 

In the eastern Brooks Range, near Mount Michelson in 

northern Alaska, fluorite occurs near and in a granitic 

batholith. Veins and veinlets are associated with altered 

rocks containing greisen or tourmaline. 

On Zaremba Island in southeastern Alaska, volcanic 

rocks of Tertiary age contain narrow veins and breccia 

zones which have chalcedony covered by fluorite. One 

breccia zone ranges from a few inches to several feet in 

thickness, with breccia fragments coated with chalcedony 

on which fluorite was deposited as incrustations 

(Buddington, 1923). This is the only fluorite lode inTertiary volcanics reported in Alaska. 

Fluorine resources in Alaska in minerals other than 

fluorite consist principally of fluorine in topaz greisen, 

and in phosphate rock. The known deposits of size are at 

Lost River, on the Seward Peninsula, where topaz greisen 

forms a mass in the buried granite that measures several 

hundred feet across and extends vertically several hundred 

feet deep. However, much of this greisen was argillized, 

and argillization destroyed the topaz without fixing all the 

fluorine in late-stage fluorite; the general fluorine content 

probably averages not more than 3-4 percent. 

The granite at Tin Creek, about 2 miles southeast of the 

Lost River mine, also is greinsenized over an area of several 

thousand square feet on the northeast end; the topaz content is unknown, though considerable. 

The phosphatic limestones of northern Alaska were discussed by Patton and Matzko (1959), who concluded that 

high-grade phosphate rock (35.8 percent P20 5) occurs in 

the Shublik Formation of Triassic age, and lower grade 

phosphate rock is present in the Lisburne Group of late 

Paleozoic age. Fluorine is present in the phosphate rock in 

carbonate fluorapatite and also in fluorite. As both these 

units crop out for a hundred miles along the Arctic foothills of the Brooks Range, they unquestionably contain 

large resources of fluorine as well as of phosphate. 

WASHINGTON-IDAHO-MONTANA-WYOMINGSOUTH DAKOTA 

By R. L. PARKER 

Fluorite is widely distributed in the Washington, Idaho, 

Montana, Wyoming, and South Dakota region; only a few 

deposits, however, are known to be of sufficient size and 

grade to be of commercial interest, and known resources 

are not large. The only deposits in the region with significant recorded production are the Challis and Meyers Cove 

deposits, Idaho, and the Snowbird, and Crystal Mountain 

deposits, Montana. Of these deposits only the Crystal 

Mountain has been a consistent producer. 

Fluorite deposits in the region can be grouped into 

several types. The most important deposits are associated 

either with volcanic rocks or with intrusive rocks of the 

Colville, Idaho, and Boulder batholiths and alkalic 

intrusive bodies. In addition to different volcanic and 

intrusive associations, the fluorite deposits in the region 

have different structural characteristics. Fillings of fissures 

and breccias byfluoriteandchalcedonywith vuggy, drusy, 

and layered features common to epithermal deposits are 

characteristic of fluorite deposits related to large volcanic 

piles in Washington and Idaho. One of the most prevalent types of occurrence is related to the contact between 

intrusive and sedimentary rocks, especially between 

granitic and alkalic intrusive rocks and limestone or other 

calcareous rocks. Fluorite at such deposits is concentrated 

in veins or breccia zones in both intrusive and country 

rocks, is disseminated in the intrusive rocks, or is disseminated or concentrated in sedimentary rocks along the contact. Some deposits are actually in the contact metamorphic aureole of the intrusives and are associated with 

tactite or skarn. Other deposits are in pegmatites that are 

in genetically related intrusive rocks or in country rocks. 

Certain occurrences of fluorite are obscure in their origin, 

and although they are found as gangue in vein deposits of 

metallic minerals, they may be unrelated except for the site 

of localization. Miscellaneous occurrences include fluorite 

as gangue in uranium deposits, and at least one fluorite 

deposit that is considered to be of evaporite origin. 

Deposits and occurrences of fluorite are described 

according to State in the order: Washington, Idaho, Montana, Wyoming, and South Dakota. 

DESCRIPTIONS OF INDIVIDUAL DISTRICTS AND DEPOSITS. 

WASHINGTON 

Fluorite occurs in a gold-silver-selenium deposit in the 

Republic district, Ferry County. The fluorite is locally 

present in chalcedony-calcite veins that are contained in 

Tertiary volcanics (Bancroft, 1914; Van Alstine, 1966). 

Fluorite is contained in quartz-calcite-chalcopyrite 

veins in the Zalla M, American Flag, and Silver Bell 

deposits in the Sheridan area, Ferry County. Some zones 

contain as much as 30 percent fluorite, but their extent is 

not known. The deposits are in Tertiary volcanics (Valentine, 1949; Van Alstine, 1966). 
WASHINGTON-IDAHO-MONTANA-WYOMING-SOUTH DAKOTA 35 

Fluorite is reported at one place in the upper part of the 

Ethel vein, in Snohomish County. The fluorite occurs 

with quartz, calcite, and bornite in granodiorite (Weaver, 

1912; Van Alstine, 1966). 

Fluorite is contained in veins 2-12 inches (5-30 em) 

thick in the Three Pinnacles-Lost River deposits, in 

Okanogon County. The fluorite is associated with 

chalcedony in the veins which cut granite (Valentine, 

1949; Van Alstine, 1966). 

Seven parallel veins of fluorite and chalcedony occur at 

the Slide deposit, in Chelan County. The veins range in 

thickness from less than 1 to 6 inches (2.5-15 em) and are 

traceable for only a few feet in a zone 300 feet (90 m) across 

in granite (Valentine, 1949; Van Alstine, 1966). 

Fluorite is a gangue mineral in a silver ore vein that cuts 

granite of the Colville batholith at the Apache claim, in 

Okanogan County. The vein is a quartz vein irregularly 

banded with pyrite, fluorite, and an unidentified black 

sulfide mineral (Valentine, 1949; Pardee, 1918; Van 

Alstine, 1966). 

Fluorite is found in veins and shear zones in Ramore, 

Gladora, and Wasco lead-silver-zinc-copper deposits in 

the Park City district, in Okanogan County. The fluorite, 

in minor amounts, is associated with quartz, metallic sulfide minerals, calcite, and sericite in deposits in quartz 

monzonite of the Colville batholith (Pardee, 1918; Van 

Alstine, 1966). 

The Mitchem fluorspar deposit is in Ferry County. It is 

the only productive deposit in Washington, having 

produced a small tonnage of acid grade and metallurgical 

fluorspar as follows: 60 tons in 1918, 152 tons in 1940-42, 

and 170 tons in 1945-46. The fluorspar is contained in a 

16-inch (40-cm) steeply dipping northwest-trending vein 

in granitic rock of the Colville batholith. The vein contains green, purple, and colorless fluorite, calcite, 

chalcedony, and some pyrite. Across mining widths, the 

material averages about 50 percent CaF2• The deposit is 

considered to be small (Van Alstine, 1966) and not to constitute a large reserve on the basis of available data. 

Thin veinlets of fluorite occur in limy argillite at the 

Montgomery deposits, in Okanogan County (Valentine, 

1949). 

Fluorite is a minor gangue mineral associated with 

quartz, ferberite, scheelite, pyrite, molybdenite, and 

chlorite in tungsten veins at the Germania mine, in 

Stevens County. The veins are mostly less than 3 feet(l m) 

thick and are contained in Cretaceous quartz monzonite 

(Becraft and Weis, 1963; Van Alstine, 1966). 

Fluorite occurs as a gangue mineral with wollastonite, 

tremolite, and quartz in the magnetite ore body at the Read 

iron deposit, in Stevens County. Mineralized rock is localized along a granite-limestone contact and fluorite is in a 

contact-metamorphic zone. Associated ore minerals are 

scheelite, chalcopyrite, and magnetite (Valentine, 1949; V:::~n A h:tinP 1 Ohh\ 

Fluorite occurs in molybdenite-bearing quartz veins 

and as an accessory mineral in adjacent granite expecially 

near schist and quartzite contacts at the Phalen Lake 

molybdenum deposit, in Stevens County (Valentine, 1949; 

Van Alstine, 1966). 

Fluorite is a minor constituent in the quartz veins of the 

Northport district, Stevens County. The quartz veins bear 

sulfide minerals and are contained in argillite and limestone cut by granite and in black slate of Paleozoic age 

(Van Alstine, 1966). 

Fluorite is reported in small lenses in gneiss and schist 

about 5 miles (8 km) east of Riverside, in Okanogan 

County (Valentine, 1949; Van Alstine, 1966). 

Fluorite at the Electric City deposit occurs in pegmatite 

lenses in granite of the Colville batholith, in Douglas 

County. Associated minerals are quartz, molybdenite, and 

pyrite (Van Alstine, 1966). 

Fluorite is contained in pegmatite in granite of the Colville batholith at the Sanpoil uranium deposit, in Okanogan County. The fluorite is violet, radioactive, and 

associated with samarskite (Van Alstine, 1966). 

Fluorite occurs as traces in gray massive quartz segregations in muscovite-rich pegmatites that cut fine-grained 

monzonite of the Loon Lake Granite at the Spokane 

molybdenum deposit, in Lincoln County (Becraft and 

Weis, 1963). 

IDAHO 

MEYERS COVE 

The Meyers Cove fluorspar district, Idaho (Anderson, 

1954a; Cox, 1954), is about 38 miles (61 km) (66 miles by 

road) southwest of Salmon, and 26 miles (42 km) northwest of Challis, Lemhi County, on Camas Creek, a tributary of the Middle Fork of the Salmon River. The deposits 

produced about 37,432 tons of fluorspar during 1951-53, 

principally from the Big Lead deposit. Other deposits in 

the district are North Pit, Anderson, Bear Trap, M and M, 

and Chamac. 

The fluorspar deposits are fissure fillings along 

northeast-trending zones which Anderson (1954a) 

attributed to a deep-seated shear in basement rocks. The 

deposits are located in Challis Volcanics (Tertiary) and 

Miocene porphyries, but these host rocks apparently had 

little effect on localization of the deposits. The deposits are 

exposed over a vertical range of more than 2,000 feet (610 

m). 

The ore bodies vary widely in size, ranging from a few 

inches in width and a few tens of feet in length to more 

than a dozen feet in width and several hundreds of feet in 

length. They average 4-5 feet ( 1.2-1.5 m) in thickness with 

thicker local bulges and are 100-300 feet (30-90 m) long. 

Big Lead has a maximum stope width of 16 feet (5 m) and 

stope length of 300 feet (90 m). Ore bodies tend to swell 

where the orientation of fissures chan~?es from northP~40:t tn 
36 GEOLOGY AND RESOURCES OF FLUORINE 

The mineral assemblage of the deposits is simple, consisting chiefly of chalcedony, fluorite, and some barite. 

The ore is layered (commonly called "banded"), and 

chalcedony and cryptocrystalline fluorite form concentric 

shells on breccia fragments and form crystalline druses. 

The wallrocks along fluorite-bearing zones are 

commonly bleached and (or) stained with iron oxides. The 

bleaching resulted from argillic alteration, with limited 

sericitic alteration close to fluorite bodies. Some of the iron 

staining is attributed to the oxidation and decomposition 

of pyrite. In places, silicified rocks are closely associated 

with the fluorite bodies. 

The Meyers Cove deposits are probably epithermal as 

indicated by the low-temperature layered chalcedony and 

the open-brecciated, vuggy and drusy nature of the ore 

which suggests near-surface deposition. The fluorite 

bodies were deposited in fissures along northeast-trending 

zones probably from hydrothermal solutions. 

These deposits have high potential as a future resource 

of fluorspar. 

BAYHORSE 

The Challis fluorspar deposits (Bayhorse district), 

Custer County (Anderson, 1954b), are located in the 

northern part of the district about 4 miles (6.5 km) southwest of Challis at the south end of the Salmon River 

Mountains. 

Fluorite was not recognized as a gangue mineral in the 

silver base-metal lodes of the Bayhorse district until the 

early 1940's. Actual location of claims for fluorspar dates 

from 1947, and exploration, development, and small production was not untill952-53 in the Keystone MountainDaugherty Gulch area. Production from the Chalspar No. 

1 deposit amounted to 475 tons of metallurgical-grade 

fluorspar and 245 tons of lower grade material. 

The Challis fluorspar deposits are fissure fillings and 

breccia impregnations in which abundant open spaces 

and fluorite-lined druses are characteristic. All deposits 

reported are in the Bayhorse Dolomite of Ordovician(?) 

age, which forms a favorable host because it is more 

brecciated than adjacent formations (Anderson, 1954b, p. 

7). The major structural feature of the area is the Bay horse 

anticline that exposes lower Paleozoic rocks comprising 

several formations: Garden Creek Phyllite, Bayhorse 

Dolomite, Ramshom Slate, and Kinnikinic Quartzite. 

Fissure veins and breccia lodes are localized along faults 

and relatively minor fault zones wholly within the Bayhorse Dolomite. Most veins have northerly trends and 

steep westerly dips. Fluorspar bodies reach widths of 

several tens of feet and lengths of several hundred feet. The 

Passed Up vein, for example, is 3-7 feet (1-2m) thick and is 

exposed for more than 200 feet (60 m) along strike. The 

vein on Chalspar No.2 claim is 12-18 feet (3.7-5.5 m) thick 

and is exposed for 900 feet (275m). Some breccia deposits 

range in diameter from a few feet to 30 feet (9 m) and can be 

traced for a hundred feet or more at the surface. · 

The deposits consist chiefly of fluorite with minor 

amounts of quartz and calcite. In some veins local masses 

of sulfides are relict from earlier mineralization. Some 

breccias have boxwork structure in which quartz forms 

thin partitions between cells and is coated with fluorite. 

Layering ("banding") is not conspicuous, but poorly 

defined concentric layers of fluorite enclose breccia 

fragments. 

The grade of the fluorspar is variable and most deposits 

require milling to upgrade the material sufficiently for 

commercial use. Samples across the Passed Up vein 

averaged 67.1 percent and 57.1 percent CaF 2 over widths of 

13 and 14 feet (4 and 4.3 m), respectively. At the Chalspar 

No. 5 the vein ran 40 percent CaF 2 over a width of 17 feet 

(5.2m). The boxwork breccias at Keystone Mountain 

assayed 30-60 percent CaF2 across 18-30 feet (5.5-9 m). 

The age of fluorspar mineralization is considered to be 

Oligocene or younger, because probable Oligocene volcanic rocks form the hanging wall of the Passed Up vein. 

The district has large potential as a future source of 

fluorspar. Surface exposures and limited exploration 

indicate fluorspar bodies sufficiently large for mining. 

Although the grade is lower than some currently mined 

deposits, future prices may be sufficiently high to allow 

beneficiation and shipment to centers of consumption. 

STANLEY AREA 

Fluorite has been discovered in the Stanley area, Custer 

County (Choate, 1962), in the following localities: (1) in 

epithermal gold-silver veins in quartz monzonitegranodiorite near the mouths of Big and Little Casino 

Creeks about 3.5 miles (5.5 km) east of lower Stanley; (2) in 

fluorite veins in the Challis Volcanics at the Lamb prospect in the northern part of the Yankee Fork district 1 mile 

(1.6 km) west of Jordan Creek-Mayfield Creek divide; and 

( 3) in a gold-silver vein in Challis Volcanics on Hindman 

Peak Ridge 1.25 miles (2 km) south of Red Mountain 

about 13 miles (20 km) north of lower Stanley (no description is available). The known deposits containing 

fluorite are the Bright Star, the Giant Spar, the Homestake, and the Gold Chance properties, and the Hide Out 

and the Lamb prospects. The only production of fluorspar 

recorded from any of these deposits was from the Giant 

Spar which reportedly yielded a few truckloads of fluorite 

during World War II. 

The Giant Spar is the largest known fluorite deposit in 

the Stanley area. It occurs as epithermal, open-space 

filling in faults and breccia zones in quartz monzonitegranodiorite. Other fluorite-quartz veins of the district 

have been explored for gold and silver, but these metals are 

not present in the fluorite of the Giant Spar. Diamond 

drilling has indicated a composite vein system that trends 

northeast and has a maximum thickness of about 15 feet 

(4.5 m). The fluorite vein is cut by a younger fault. A chip 

sample across a 10.6-foot (3.2-m) width of the vein contained 71.5 percent CaF2• Rhyolite and basalt dikes cut the 
WASHINGTON-IDAHO-MONTANA-WYOMING-SOUTH DAKOTA 37 

quartz monzonite in the vicinity of the deposit, but the 

relation of the fluorite to the dikes was not stated by 

Choate (1962). Presumably the fluorite mineralization was 

related to Challis volcanism. 

The fluorite is pale lavender, colorless, and pale green, 

and forms "banded" veins. Vugs are common and some 

are lined with euhedral fluorite crystals. 

The Bright Star deposit contains a composite fluorite 

vein zone 3 feet (1m) thickcomposedofindividual veins of 

fluorite up to 6 inches ( 15 em) thick and stringers of quartz. 

The vein zone contains 60-80 percent fluorite. The extent 

of the deposits is unknown because of the caved condition 

of the workings. 

The Homestake, Gold Chance, and Hide Out claims 

contain minor fluorite in gold-pyrite-quartz-fluorite 

veins. The Hide Out workings are anomalously 

radioactive. 

The Lamb prospect in the northern part of the Yankee 

Fork district contains fluorite in a series of veins, stringers, 

and breccia fillings along a northeast-trending zone that is 

at least a mile ( 1.6 km) long and several hundred yards 

wide. The zone cuts the Challis Volcanics. The largest vein 

in the zone is traceable for 600 feet (180m) and ranges in 

thickness from a few inches to 4 feet ( 1.2 m). A sample 

across a 4-foot ( 1.2-m) vein width contained 39.4 percent 

CaF 2 and showed fluorite, calcite, chalcedony, quartz, and 

breccia; no metallic minerals were detected. 

Too little information exists on the Stanley fluorite 

deposits to assess their potential. Some veins are high 

enough in grade and are wide enough to merit investigation of their vertical and longitudinal extent in order to 

determine the presence or absence of minable ore bodies. 

BIG SQUAW CREEK 

The Big Squaw Creek fluorspar deposit, previously 

known as the Smothers property or the Noussan mine, is 

located on the Salmon River between Big Squaw Creek 

and Smith Gulch in the Salmon River Breaks Primitive 

Area. It is 18 miles (29 km) downriver from the end of the 

road at Corn Creek. The description of the deposit 

presented here is based on Weis and others (1972). 

The deposit was prospected for gold as early as 1860, but 

was not claimed until 1937. Properties have passed 

through considerable reassignment and relocation to the 

present time. Exploration under a contract with Defense 

Minerals Exploration Administration was conducted in 

1957-58 including geologic mapping, trenching, and 

diamond drilling as well as additional work by the owners. 

No production has been recorded from the claims 

although inferred reserves are considered to be about 

100,000 tons of fluorspar containing 70 percent CaF2• 

The fluorspar deposit consists of three ore shoots on the 

hanging wall (or east side) of a persistent quartz vein that 

strikes N. 10° W. and dips 60° E. The vein is contained in 

biotite gneiss that is intruded by quartz monzonite about a 

mile (1.6 km) to the west. The vein is one of many quartz 

veins that occur in a zone trending N. 10°-15° W., and so 

far as known, contains the largest bodies of fluorite. 

The fluorite is present as small stringers and as crystals 

lining vugs in the quartz vein, and as ore shoots along the 

hanging wall of the vein. It is both massive and coarsely 

granular and ranges from transparent through green to 

purple. 

Three ore shoots have lengths of 600, 260, and 220 feet 

(180, 80, and 67 m) and average widths of 7.2, 7.9, and 7.1 

feet (2.2, 2.4, and 2.2 m), respectively. Average grades of the 

shoots as determined from surface samples are 67 .50, 73.93, 

and 70.50 percent CaF2 respectively. Diamond drilling on 

the 600-foot-long shoot mentioned above indicates that it 

extends to a depth of at least 300 feet (90 m) but may 

decrease in grade in depth. 

The deposit is apparently related to the Idaho batholith 

because of its proximity thereto, and has certain features in 

common with the Crystal Mountain, Spar, and Snowbird 

deposits of Montana. Although 100,000 tons of ore with a 

grade of 70 percent CaF2 is inferred for the deposit, it 

remains submarginal because of its remoteness. 

OTHER DEPOSITS 

A narrow vein of high-grade fluorite is reported to occur 

in the Pungo Creek area, Valley County (Anderson and 

Van Alstine, 1964). The vein is in porphyritic diorite cut 

by mafic dikes. 

Fluorite occurs in a northeast-trending vein at the Simer 

prospect, 6 miles (9. 7 km) north-northwest of Salmon. The 

vein is composed mostly of radioactive jasperlike rock as 

much as 2-3 feet (l m) thick. It cuts quartz monzonite and 

contains monazite, variable amounts of barite, and purple 

and colorless fluorite (Anderson, 1959, p. 89). 

Fluorite occurs in a number of gold lodes in the 

Edwardsburg district, Valley County, but is most 

abundant in upper Smith Creek at the Independence 

mine. The fluorite is disseminated in coarse grains in 

irregular quartz veins 3 feet (l.m) or more in width which 

occur at intervals in a silicified zone that is several 

thousand feet long and 200 feet ( 60 m) wide (Clyde P. Ross, 

in Burchard, 1933, p. 14). The deposit is in the Precambrian Y Yellowjacket Formation that in the vicinity of 

the mine consists mainly of schistose argillites and quartzites and a layer of crystalline limestone at least a hundred 

feet (30m) thick. The silicified rock contains scattered sulfides: pyrite, sphalerite, tetrahedrite, and galena (Shenon 

and Ross, 1936, p. 28). 

Fluorite is a gangue mineral in tungsten-bearingquartz 

veins in quartzite in the Blue Wing district, Lemhi 

County. According to Callaghan and Lemmon (1941) it is 

prominent only in a zone extending 600 feet (180m) from 

the granite contact on the intermediate level of the Ima 

mine where it bears a definite zonal relation to the granite. 

Associated minerals in the veins are orthoclase, 

rhodochrosite, huebnerite, pyrite, tetrahedrite, chalcopyrite, bornite, galena, sphalerite, molybdenite, and 

scheelite. Some fluorite is also disseminated in the granite. 
38 GEOLOGY AND RESOURCES OF FLUORINE 

Fluorite occurs as a minor accessory mineral associated 

with aquamarine disseminated in albitized quartz monzonite in certain parts of the Sawtooth batholith in central 

Idaho (Reid, 1963). 

MONTANA 

CRYSTAL MOUNTAIN 

The Crystal Mountain fluorspar deposit is located on 

the Rye Creek-Sleeping Child Creek divide, in the southwestern part of Ravalli County. It is 26 miles (42 km) by 

road east of Darby and lies at an elevation of about 6,800 

feet (2,100 m). 

The deposit consists of two separate groups of 

outcrops about 3,000 feet (900 m) apart. An eastern group, 

called the Retirement claims, consists of two small elliptical outcrops of fluorspar 60 feet (18m) wide and 150 feet 

(45 m) long. The fluorspar bodies are more resistant to 

erosion than the enclosing rocks and hence form the crests 

of knolls (Taber, 1953). Sahinen (1962) suggested that the 

bodies are erosion remnants of a flat-lying vein and 

described the enclosing rock as granite and fine-grained 

gray gneiss with an overlying mass of white quartz in the 

hanging wall and vein lets of glassy quartz in the footwall. 

A larger western group, called the Lumberjack claims, is 

the site of an open pit mine. This group consists of three 

main bodies of fluorspar 100-200 feet (3Q-60 m) wide and 

200-400 feet (6Q-120 m) long which are tabular and dip 

easterly 10°-35°. These bodies, according to Weis and 

others (1958), are underlain by coarse-grained biotite 

granite that contains inclusions of hornblendeplagioclase gneiss, biotite-quartz-plagioclase gneiss and 

pegmatitic granite. Foliation in the inclusions strikes 

about north and dips 20°-30° E. nearly parallel to the 

fluorspar bodies. Small dikes of granite cut both gneiss 

and fluorspar. 

The fluorspar at the Crystal Mountain deposit is exceptionally high grade and remarkably uniform in quality. 

The average grade (Sahinen, 1962) is more than 96percent 

CaF 2• Weighted averages of nine samples taken by the U.S. 

Bureau of Mines (Taber, 1952) contained 97.2 percent 

CaF2, 1.44 percent Si02, and 0.13 percent Fe. The ore consists of massive crystalline fluorite and local minor 

amounts of biotite, quartz, feldspar, sphene, rare-earthbearing apatite, amphibole, fergusonite, thorianite(?), and 

thortveitite (Parker and Havens, 1963 ). The fluorite ranges 

in crystal size from 0.1 inch to at least 1 inch (2.5 mm-2.5 

em) across and ranges in color from white through pale 

green to deep purple. The minor minerals are concentrated in deep-purple fluorite aggregates that are radioactive and which occur mostly at the margins of the 

fluorspar bodies. Spectrographic analysis of run-of-themine fluorite shows the presence of minor aluminum, 

magnesium, barium, nickel, titanium, and niobium; 

analysis of the dark-purple fluorite indicates amounts of 

iron, potassium, aluminum, silicon, uranium, thorium, 

niobium, rare earths, yttrium, phosphorus, and scandium 

higher than the average mined fluorite. 

The Crystal Mountain deposit is distinguished by 

several characteristic features. The ore bodies are nearly 

pure fluorite and are sharply delineated from the 

enclosing host granite that is considered to be part of the 

Idaho batholith. Younger granite(?) dikes cut both fluorite 

and enclosing host granite. The host granite also contains 

ordinary quartz-feldspar pegmatites. Radioactive fluorite 

which contains an anomalous content of rare-earth 

elements, niobium, thorium, and scandium forms zones 

roughly bordering the fluorite bodies. Some minerals 

enclosed in radioactive fluorite are found commonly in 

pegmatites. Indeed, thortveitite has been found only in 

pegmatites. 

The origin of the Crystal Mountain deposit is not clear. 

The characteristics mentioned above point to a plutonic 

origin related to pegmatites. The deposits of fluorite 

might be considered to be monomineralic pegmatites. 

SNOWBIRD 

The Snowbird deposit, also known as the F and S 

fluorspar mine, is located on the Montana-Idaho 

Boundary at the head of Cedar Log Creek, just below the 

crestline of the Bitterroot Range in southwest Mineral 

County. The deposit, which is covered by 19 unpatented 

claims, was mined for fluorspar in 1956-57 by the F and S 

Mining Co., producing approximately 6,500 short tons of 

metallurgical-grade fluorspar. The ore reportedly has 

been exhausted (Sahinen, 1962). 

The Snowbird has certain features that suggest genetic 

similarities with the Crystal Mountain and Spar deposits. 

The deposit is a zoned quartz-calcite-fluorite body that 

Clabaugh and Sewell (1964) described as a carbonatite 

"pegmatite." It is discordantly intruded into the Precambrian Wallace Formation of the Belt Supergroup which at 

this locality consists of argillite, argillaceous limestone, 

slate, and limy quartzite. These rocks are intruded by rocks 

of the Idaho batholith south .of the deposit, and in the 

vicinity of the deposit they have been sufficiently 

thermally metamorphosed to produce metacrysts of scapolite in the argillaceous beds (Sahinen, 1962). 

The fluorspar deposit lies in a pegmatite pod that is at 

least 600 feet ( 180 m) long and 100 feet (30m) wide and has 

an east-west long axis. The major part of the pod is 

massive white quartz that forms the hanging wall of the 

main fluorspar body. The quartz mass contains no 

inclusions, but euhedral crystals of quartz can be 

recognized protruding from the mass and some crystals are 

as much as 20 feet (6 m) long (Clabaugh and Sewell, 1964). 

The quartz forms an incomplete envelope around the calcite body, and fluorite is located in pockets in the calcite at 

the calcite-quartz contact. Two main bodies of fluorite 

were 120 feet (37m) and 40 feet (12m) long. The fluorspar 

assayed 96.2-96.5 percent CaF2 (Sahinen, 1962). 

The deposit contains-in addition to quartz, calcite, 

and fluorite-gersdorffite (NiAsS) and panstte 

[Ca(Ce,La,Y)/C03) 3F2]. These rare minerals have not 
WASHINGTON-IDAHO-MONTANA-WYOMING-SOUTH DAKOTA 39 

been noted in other fluorspar deposits in the region, but 

rare-earth elements, especially yttrium, are associated with 

fluorite at the Crystal Mountain deposit near Darby. The 

Snowbird deposit is of pegmatitic origin and is probably 

related to the Idaho batholith. 

SPAR 

The Spar mine is located on the ridge between Dry Creek 

and Bear Creek, in central Mineral County about 12 miles 

(19 km) west of Superior (Ross, 1950; Sahinen, 1962). 

The Spar claim was originally located in 1943 by Mr. 

Joseph Brooks and was developed in 1944, during which 

time an unknown amount of ore was mined. Additional 

fluorspar deposits were discovered nearby in 1948 in the 

Wilson Creek drainage south of Dry Creek and in 1949 in 

nearby Lime Gulch. The Spar and Wilson Creek properties, under control of various subsequent operators, together produced 318 tons of fluorspar in 1948, 422 tons in 

1949, and 41 tons in 1950 (last reported production). 

Individ~al property production is not known. 

The Spar deposit is localized in the Wallace Formation 

of the Precambrian Belt Supergroup which in the area 

consists of quartzite, argillite, calcareous quartzite, dolomite, and ferruginous limestone; most of the rocks strike 

northwest. The rocks in the vicinity of the deposit have 

undergone moderately intense and somewhat irregular 

folding, and locally contain steep, sheeted zones and zones 

of intense brecciation. Conspicuous lenticular milkywhite quartz bodies cut the Wallace Formation, and at 

least one of them contains fluorite (Spar mine). In the 

general area of Ann Arbor and Bear Creeks quartz lenses 

exceed 100 feet ( 30 m) in length, and some crop out along a 

nearly straight line. The lenses are discordant and show no 

parallelism or obvious relation to the trends of the beds of 

the Wallace Formation that they cut. The larger lenses of 

quartz trend N. 70° E. to S. 70° E. and have northwesttrending joints. 

Igneous rocks are not exposed in the area. The Idaho 

batholith which lies about 35 miles (55 km) to the south 

and a diabase sill about 10 miles (16km) to the west are the 

closest known occurrences of igneous rocks. 

The fluorspar at the Spar mine occurs in irregular pods 

and lenses ranging in diameter from several inches to 

several feet. A sample cut by Clyde P. Ross (1950, p. 208) 

across a 45-inch (1.5-m) face in the main pit at the Spar 

property assayed 98.57 percent CaF.2

, 1.18 percent Si02, 

and 0.14 percent carbonate. 

The fluorite at the Spar property occurs with calcite and 

ankerite and minor galena, tetrahedrite, and pyrite. A 

large body of milky-white quartz 30 feet (9 m) wide and 150 

feet (45 m) long forms the hanging wall. Some large crystals of quartz a foot or more across are exposed in the Spar 

prospect. 

The Spar fluorspar deposit resembles the Snowbird 

deposit in some respects. Both deposits lie in the calcareous Wallace Formation of the Belt Supergroup and 

both are associated with calcite and minor sulfides and 

with massive milky-white quartz bodies containing large 

quartz crystals suggestive of pegmatitic orgin. Neither 

deposit can be related directly to visible igneous rocks 

although the Snowbird deposit is close to exposed rocks 

reported as part of the Idaho batholith. 

OTHER DEPOSITS 

The Jetty mine, also known as the Balkan lode, is on the 

north slope of Garrity Hill, 6 miles (10 km) west of Anaconda, Deer Lodge County. Fluorite occurs as. a gangue 

mineral in a metalliferous vein at an intermediate level in 

the mine. The vein is composed of quartz, fluorite, barite, 

and the metallic sulfides-boulangerite, pyrite, sphalerite, 

tetrahedrite, and stibnite. Host rock of the deposit is 

Madison Limestone (Mississippian) and Quadrant 

Quartzite (Pennsylvanian). Intrusive rocks of Boulder 

batholith age occur in the region. The extent of fluorite in 

the mine is not known but the mineral might be recovered 

as a byproduct in the milling of the sulfide ore (Sahinen, 

1962). 

The Weathervane Hill prospect lies south of the Smelter 

stack at Anaconda, in Deer Lodge County. Fluorite occurs 

in a fault zone between upper Paleozoic limestone and 

upper Mesozoic strata. The fluorite is distributed irregularly in pockets a few inches to a few feet in maximum 

dimension. The potential for commercial fluorspar is low 

for anything but very small-scale mining (Sahinen, 1962). 

The Silver Bow deposits are 6 miles ( 10 km) west of Butte 

along Silver Bow Creek, in Silver Bow County. Interstate 

Highway 90 (U.S. Highway 10) and four railroads cross 

the property. The Bull Moose, Merrimac, and Wrong Font 

are claims in this group of deposits. Fluorite occurs in 

shoots within a gold-silver(?)-bearing fracture zone along 

a fault(?) contact between andesite and quartz monzonite 

and aplite. The mineralized zone extends more than 2,000 

feet (600 m) in a northwest direction and in places is more 

than 100 feet (30m) wide. The rocks in the zone are silicified and stained with iron oxides. The principal bodies of 

fluorspar are on the east end of the Bull Moose claim where 

layers of fluorite range from an inch (2.5 em) to 3.5 feet (I 

m) in width and are tens of feet in length. An average of six 

samples gave 83.84 percent CaF2, 13.02 percent Si02, 2.02 

percent R20s, and 1.40 percent CaCOs (Sahinen, 1962; 

Ross, 1950). Exploration has been insufficient to define 

the extent of fluorspar at the deposits; the grade and size of 

bodies reported, however, would indicate potential for 

small-scale mining. Actual operations might be hampered 

by the highway right-of-way ·that runs through the 

properties. 

The Bald Butte mine lies within the Marysville mining 

district, 17 miles (22 km) northeast of Helena, Lewis and 

Clark County, and 3.5 miles (5.5 km) southwest of the old 

mining camp of Marysville. Fluorite occurs with quartz as 

the gangue of metallic ore that was originally developed 

and mined by underground workings that are no longer 
40 GEOLOGY AND RESOURCES OF FLUORINE 

accessible. The deposit is in limestone of the Helena 

Formation of the Precambrian Belt Supergroup which has 

been intruded and homfelsed by dikes and sheets of microdiorite and later cut by diorite porphyry dikes of Belmont 

Porphyry. All these rocks are shattered, and infiltrated 

with quartz and fluorite. The deposit may be related to a 

porphyry of middle Tertiary age. Sahinen (1962) concluded from the examination of dump specimens and 

Barrell's (1907) description of the deposit that no fluorite 

ore could be marketed from the deposit without extensive 

beneficiation. 

The Boeing prospect is located about 3.5 miles (5.5 km) 

west of Austin in the Austin mining district, Lewis and 

Clark County. Fluorspar is contained in small irregular 

pods in the Madison Limestone adjacent to an altered and 

mineralized biotite rhyolite dike. The limestone is 

intruded by quartz monzonite a short distance south of the 

deposit. The principal fluoritebody was 3-6 feet (1-2m) 

wide and exposed over a height of 7 feet (2.1 m). A sample 

taken near the surface across a 41-inch (1.1-m) width 

yielded 81.76 percent CaF 2, 10.09 percent Si02 and 2.52 

percent carbonates (Ross, 1950). The extent of the 

fluorspar has not been determined, but reports indicate 

that fluorite bodies are small and irregularly distributed. 

In the Sweetgrass Hills in northwestern Liberty County, 

just south of the Canada-United States boundary the 

principal fluorspar bodies are in Tootsie Creek (Ross, 

1950; Sahinen, 1962); they consist of veins, replacement 

seams, and minor disseminations in or adjacent to marbleized Madison Limestone near contacts with porphyritic 

syenite of the laccoliths and stocks of the Sweetgrass Hills. 

Most of the fluorspar masses closely follow bedding or 

sheeting in the limestone. Some masses are irregular, some 

nearly flat, and others roughly spherical. Some mineralized zones attain widths of 10 feet (3m) and some can be 

followed continuously along strike for as much as 50 feet 

(15m). Most individual bodies are much smaller and are 

scattered in the Tootsie Creek area through a zone in limestone that is well over 2,000 feet (600 m) long and at most is 

several hundred feet wide. The fluorite is intimately intergrown with other minerals; a 200-mesh grind is required 

to release the fluorite and obtain a 95-percent CaF2 concentrate. The CaF 2 content of the mineralized material 

ranges from 3.06 to 87.01 percent averaging somewhat less 

than 40 percent in bodies of minable size. The silica 

content ranges from 1.68 to 43.83 percent. The area has 

potential for minable fluorspar bodies, but exploration 

has been insufficient to define the extent of fluorite mineralization. 

Minor fluorite is reported in the South Moccasin 

Mountains, a satellite uplift of the Judith Mountains 

intrusive center (Miller, 1959; Sahinen, 1962). The fluorite 

occurs as a gangue mineral in a gold-silver vein, in a 

dickite clay body, and in an area of breccia and altered rock 

adjacent to a large fault. All the deposits are related to 

alkalic rocks-porphyritic syenite and leucorhyolite-which intrude the Madison Limestone. Fluorite is 

also reported in at least one zone within the intrusive rock. 

At the American Flag prospect near the summit of 

Judith Peak, Fergus County, fluorite and quartz form a 10-

foot (3-m) vein that cuts an altered zone in a syenite 

intrusive in the Judith Mountains alkalic intrusive center 

(Sahinen, 1962). The vein also contains lead, silver, and 

gold. Another nearby occurrence of fluorite is in fine 

seams and disseminated grains in a 5-foot (1.5-m) 

tinguaite dike. The fluorite-quartz vein contains 22.8-34.0 

percent CaF2, 52.8-66.9 percent Si02, 2-4 percent lead, 

0.1-0.5 ounce silver per ton, and a trace of gold. Other, perhaps major, fluorspar deposits are veins and replacement 

seams in Madison Limestone in and near the mine. The 

property was being developed in 1971 (R. G. Worl, oral 

commun., 1971). 

Fluorite at Antone Peak in the Little Rocky Mountains, 

in Phillips County (Sahinen, 1962), is sparsely 

disseminated in porphyritic syenite that intrudes sedimentary rocks of varied lithology ranging in age from 

Middle Cambrian to Late Cretaceous. 

An occurrence of fluorite is reported in the Pryor 

Mountains at the Old Glory mine, 12 miles (19 km) east 

of Warren, Carbon County (Sahinen, 1962). Fluorite is 

associated with uranium minerals in the Madison Limestone. The fluorite occurs as ovules and spheroids that 

have concentric structure and are considered to be replacements of oolitic structures in the limestone. 

WYOMING 

Several deposits of fluorite in the Bear Lodge Mountains 

about 10 miles (16 km) north of Sundance occur in a 

north-trending zone about 0.5 mile (0.8 km) wide and 

about 3 miles (5 km) long. Production of fluorspar from 

the district has been less than a ton. Fluorite is localized in 

limestone and sandstone that are intruded by Tertiary 

hypabyssal alkalic rocks (phonolites and trachyte porphyries). Bodies of fluorite for the most part are only a few 

feet long and are in the form of lenses parallel to bedding 

planes. Some fluorite is disseminated in the Minnelusa 

Sandstone and some is found in veins in a breccia zone in 

the intrusive rocks. The fluorite is associated with calcite, 

quartz, siderite, and orthoclase. CaF 2 content of the 

fluorite lenses ranges from 5 to 90 percent (Osterwald and 

others, 1959, p. 69). The deposits are similar in some 

respects to the central Montana occurrences in which 

alkalic and carbonate rocks are the hosts of the deposits. 

Fluorite is reported in a pegmatite in granite at the Bear 

deposit, in Laramie County. Twenty tons of fluorite was 

stockpiled in 1944 as a byproduct of feldspar mining 

( Osterwald and others, 1959). 

In the northern part of the Bighorn Basin a carbonate 

rock sequence of Permian age is reported by De Koster 

(1960, p. 53-55) to contain 12-15 percent fluorite. This 

fluorite is considered to be of primary sedimentary origin 
NEVADA-UTAH-OREGON-CALIFORNIA-ARIZONA 41 

as a precipitate from saline waters at a stage in evaporation shortly preceding that at which gypsum is formed 

(Gulbrandsen and Reeser, 1969). The extent of the Bighorn Basin fluorite occurrence is not known, but the large 

size of many marine evaporite deposits would suggest the 

possibility of large low-grade new-type fluorite deposits. 

SOUTH DAKOTA 

Fluorite in minor amounts has been found in drill core 

from the Minnelusa Formation in the Pass Creek area, in 

Custer County. The mineral has also been identified in 

minor quantities in the Minnekahta Limestone about 25 

miles (40 km) southwest of Custer (Roberts and Rapp, 

1965 ). 

Fluorite is reported as a gangue mineral in several gold 

mines of the northern Black Hills: Ross Hannibal, Ulster, 

Hardscrabble, Pennsylvania, Cutting, Boscobel, Double 

Standard, Hidden Treasure, and Homestake mines, 

Lawrence County. It occurs with autunite and limonite at 

the Davier mine (Roberts and Rapp, 1965 ). Some of the 

fluorite may be of Tertiary age and related to volcanism, as 

it impregnates rhyolite at the Hardscrabble mine. 

NEVADA-WESTERN UTAH-SOUTHEASTERN 

OREGON-SOUTHEASTERN 

CALIFORNIA-WESTERN ARIZONA 

By R. G. WoRL and W. R. GRIFFITTS 

The region made up of Nevada, western Utah, southeastern Oregon, southeastern California, and western 

Arizona contains numerous fluorspar deposits and 

fluorite occurrences. Most of the deposits are small, 

undeveloped, and poorly described, as compared to the 

numerous well-documented fluorspar deposits, many 

with substantial production, in Colorado, New Mexico, 

and trans-Pecos Texas. Nevertheless, this region contains 

three major fluorspar districts: Spor Mountain, Utah; 

Fluorine, Nev.; and Broken Hills, Nev., and one of intermediate size: Indian Peak Range (Cougar Spar and other 

mines), Utah (localities shown by Worl and others, 

197 4 ). Most fluorspar deposits in this region have been discovered and developed since 1935. Burchard in 1933 (p. 24) 

listed only four important fluorspar deposits in this 

region: the Castle Dome district, Arizona, the Fluorine district, Nevada, the Afton Canyon deposits, California, and 

the Silver Queen mine, Utah. Lindgren (1933b, p. 164) 

listed several fluorite gangue occurrences in this region, 

but very few of the now-known fluorspar deposits. In contrast, most of the known fluorspar districts in Colorado 

and New Mexico were listed by Lindgren ( 1933b, p. 165) or 

Burchard (1933, p. 24), suggesting that Colorado and New 

Mexico were more intensely prospected for fluorspar in 

the early days than were the States in this region. 

Fluorspar in this region occurs in veins, mantas, and 

pipelike bodies in and associated with volcanic rocks, in 

contact zones and stockworks of hypabyssal and plutonic 

intrusive rocks, in veins and mantas of indefinite association, in volcaniclastic sediments, and in pegmatites. Other 

potential fluorine resources are topaz-bearing volcanic 

rocks, and fluorapatite in replacement iron ore bodies. 

Most fluorspar deposits in western Arizona and southeastern California are layered ("banded") and crustiform 

veins composed of fluorite, barite, black calcite, calcite, 

manganese oxides, and in places argentiferous galena, 

pyrite, and gold-bearing quartz. Fluorite is uncommonly 

the rna jor mineral present. Most of these deposits are welldefined veins in nearly vertical fracture systems, although 

in the Bouse district, in the Trigo Mountains, and in the 

Harquahala Mountains, Ariz., fluorite, barite, calcite, and 

black calcite occur as breccia cement and space filling in 

small concordant tabular bodies in volcanic agglomerates 

and flows (Van Alstine and Moore, 1969). Most of the 

fluorspar veins are in rhyolitic to andesitic volcanic rocks, 

pelitic metamorphic rocks, and granitic plutonic rocks. 

Several have had small fluorspar production, less than 

10,000 tons, whereas many have had considerable lead, 

silver, gold, and manganese-oxide production. Examples 

of deposits with appreciable metal and manganese oxide 

production are those in the Vulture Mountains, 

Harquahala Mountains (Snowball, etc. deposits), Trigo 

Mountains, and Castle Dome district, Arizona, and the 

Orocopia, Afton Canyon, Red Bluff, and Warm Springs 

deposits, California. The Castle Dome district, Yuma 

County, Ariz., is described in more detail in later pages. 

In Nevada, Utah, and the Clark and Ivanpah 

Mountains, Calif., fluorspar veins and manto deposits are 

composed of fluorite, calcite, barite, quartz, and 

chalcedony and in a few places base- and precious-metal 

minerals. Layering and crustification are common and 

fluorite is generally the major mineral present. Most of 

these deposits are in volcanic rocks, rhyolite to andesite in 

composition, and in carbonate sedimentary rocks. Some 

are in granitic plutonic rocks. 

Many of the deposits are believed related genetically to 

Tertiary volcanism although not all are layered-vein types 

occurring in volcanic rocks such as at the Baxter (Kaiser) 

mine in the Broken Hills district, Nevada, to be described 

in later pages. Other examples of volcanic-related 

deposits, lying in Horton's (1961, p. 8) "western epithermal fluorspar belt" in Nevada, occur in Pershing, 

Churchill, Mineral, and Nye Counties. Similar deposits 

elsewhere in the region are in the Indian Peak Range 

(Cougar Spar and other mines), Utah, and Wah Wah 

Mountains, Utah. Some deposits are similar to volcanicrelated types but lack evidence of volcanic connections; 

these occur in eastern Nevada and in the Clark and 

Ivanpah Mountains, Calif. 

Several major structural zones appear to have localized 

fluorspar deposits in the region. The "western epithermal 
42 GEOLOGY AND RESOURCES OF FLUORINE 

fluorspar belt" of Horton (1961) is a vaguely defined 

structural zone. Its northerly trend, about 50 miles (80 km) 

wide and 200 miles (320 km) long, through western 

Nevada is defined partly by the dominant northerly orientation of ranges in this part of the Basin-Range province. 

Other significant structures appear to have been more 

important in localizing districts, however, and these 

extend out of the western belt and have controlled localization of other districts in central and southeastern 

Nevada. For example, the Boulder Hill mine and Mount 

Montgomery Pass district in western Nevada and the 

Fluorine district and Nipton deposit in southern Nevada 

lie within the prominent northwesterly oriented Walker 

Lane structural zone. Similarly, farther north, the Broken 

Hills district, Union district, Quinn Canyon Range 

district, Lincoln mine, and Wells Cargo deposit lie along a 

northwesterly structural zone at the northeast edge of the 

Walker Lane. Deposits in eastern Nevada and western 

Utah are largely within two prominent northeasttrending structural belts, one extending from White Pine 

County, Nev., to the vicinity of Park City, Utah, and the 

other from Lincoln County, Nev., to the vicinity of Marysvale, Utah. 

In western Arizona and southeastern California, fluorite 

deposits are largely restricted to a northwesterly structural 

zone that terminates near Phoenix. This area is 

conspicuous on the tectonic map of the United States 

because of the shortness and orientation of its northeasttrending mountain ranges, which contrast with the longer 

ranges having rather consistent northerly or north· 

westerly trends. Part of this aberrant structural grain 

probably resulted from the abundant, very young, northeasterly faults with right-lateral movement, of which the 

Garlock fault of California is an example, that may postdate the fluorspar mineralization. Part of the structure 

certainly is older than these faults and is part of the set of 

northwest-trending lineaments that are found through 

much of the Western Cordillera. This northwest-trending 

set of structures is perhaps related to the Texas lineament 

that is parallel to it and about 100 miles (160 km) north of 

it; the Texas lineament weakens northwestward as the 

southwestern Arizona lineament strengthens. The southwestern Arizona lineament may curve southward as it 

weakens, merging into north-trending structures that prevail near the Arizona-New Mexico State line. 

Fluorspar occurs in carbonate rocks throughout the 

"western epithermal fluorspar belt" of Nevada (Horton, 

1961, p. 6), in the Union district, Nevada, at several 

localities in White Pine County, Nev., at the Wells Cargo 

mine, Lincoln County, Nev., in the Clark Mountains, 

Calif., in the Star district, Utah, and in minor amounts in 

carbonate rocks at numerous other localities in these 

States. At most of these localities only veins have been 

recognized; replacement bodies as mantos along poorly 

defined fluorspar veins in carbonate sedimentary rocks 

have been noted at the Wells Cargo mine, in the Clark 

Mountains (Crosby and Hoffman, 1951, p. 630), and in the 

Quinn Canyon Range, Nev. Fault-controlled replacement bodies in limestone are present in the Daisy mine, 

Fluorine district, Nevada (Cornwall and Kleinhampl, 

1961, p. J20). The fluorspar deposits in the Quinn Canyon district, described below, are spatially related to intrusive rocks. Areas underlain by carbonate rocks containing 

either fluorspar veins or intrusives with high fluorine content should be excellent prospecting targets for large replacement bodies. Fluorspar replacement bodies may not 

be readily noticeable to the naked eye. For example, finegrained fluorspar in replacement bodies at the Wells 

Cargo mine is similar in texture and color to unaltered 

limestone, and at some locations in the Clark Mountains, 

Calif., abundant sericite tends to mask the fluorite. 

Fluorspar veins and mantas in this region are 

commonly in, or related to, Basin-Range bounding faults 

of Tertiary age and occur scattered along some fault 

systems, commonly as isolated pods. 

Many of the deposits in the Nevada-western Utahsoutheastern Oregon -southeastern California -western 

Arizona region have had minor production, less than 

50,000 tons; the Indian Peak Range and nearby districts 

(Cougar Spar, Staats, and other mines), Utah, have produced more than 50,000 tons; the Spor Mountain district, 

Utah, has produced more than 100,000 tons; and the 

Fluorine district (which contains other deposits besides 

veins and mantas) and the Broken Hills district (Baxter 

mine), Nevada, have each produced more than 150,000 

tons. 

Pipelike fluorspar bodies are present at Spor Mountain, 

Utah (Staatzand Osterwald, 1959), and in the Fluorine district, Nevada (Cornwall and Kleinhampl, 1961). In both 

areas the bodies occur in fractured dolomite and are fault 

controlled. At Spor Mountain, described in more detail 

below, most of the fluorspar occurs in the pipes, veins 

being of minor importance. The pipes in the Fluorine district are part of a complex of fluorspar fissure veins, 

breccia zones, mantas, tabular replacement bodies, and 

pipelike bodies in dolomite which has been intruded by 

hypabyssal bodies of rhyolite. Fluorspar production and 

estimated reserves at Spor Mountain, all from the pipes, 

exceed 350,000 tons (Thurston and others, 1954, p. 48). 

Three occurrences of fluorite in volcaniclastic sediments have been recorded: Spor Mountain, Utah (Staatz 

and Griffitts, 1961; Staatz, 1963), Honey Comb Hills, Utah 

(McAnulty and Levinson, 1964), and Rome, Oreg. 

(Sheppard and Gude, 1969). At Spor Mountain fluorite 

occurs in a water-laid tuff on the flats just west of the area 

of the fluorspar pipes described above. Microscopic 

fluorite occurs dispersed through altered tuff and in a finegrained intergrowth with opal and chalcedony in nodules 

up to 12 inches in diameter. These nodules, probably 

replaced limestone pebbles and cobbles, are dispersed 
NEVADA-UTAH-OREGON-CALIFORNIA-ARIZONA 43 

through the altered tuff and make up several percent of 

large bodies of mineralized rock. X-ray analyses of 16 

samples of altered tuff containing no large fluorspar 

nodules. indicate an average of about 3 percent fluorite 

with a range from less than 1 percent to 8 percent fluorite 

(D. A. Lindsey, oral commun., 1971). The Honey Comb 

Hills deposits are similar to those at Spor Mountain but 

· smaller in scale. Fluorite content of near-surface samples 

from the Honey Comb Hills averages 6.3 percent and is as 

much as 10 percent (McAnulty and Levinson, 1964, p. 

773). Both the Honey Comb Hills and Spor Mountain deposits are thought to have formed from laterally spreading 

hydrothermal solutions (McAnulty and Levinson, 1964, p. 

773; Staatz and Griffitts, 1961, p. 948-949). Both deposits 

contain anomalous amounts of beryllium. The Spor 

Mountain deposits, which constitute the World's largest 

known resource of beryllium, have been mined since 1969 

for their beryllium content; fluorine is not being recovered 

at present (1973). 

Near Rome, Oreg., fluorite occurs as submicroscopic, 

nearly spherical grains in tuff, tuffaceous mudstone, and 

mudstone of a lacustrine deposit of Tertiary age. Fluorite 

content is generally less than 5 percent, but is as much as 16 

percent in some zones (Sheppard and Gude, 1969, p. D69). 

According to Sheppard and Gude (1969, p. D69) the 

"fluorite probably formed during diagenesis in sediments 

that had been deposited in an alkaline, saline lake." 

No fluorspar has been produced from any of the deposits 

in volcaniclastic sediments. 

Several tactite bodies in the Nevada-western Utahsoutheastern Oregon -southeastern California -western 

Arizona region, many mined for their tungsten content, 

contain appreciable fluorite. Examples are deposits in the 

Tushar and Mineral Ranges and Star district, Utah, the 

Tern Piute mine, Nevada, and the White Mountains, 

·calif. Fluorite was obtained as a byproduct of tungsten 

mining at the Tern Piute mine by treating tailings from 

the milling operations (Horton, 1961, p. 13). 

Replacement iron ore deposits in the Iron Springs 

district, Iron County, Utah, contain fluorapatite. 

Although the fluorine content is less than 1 percent, 

fluorine was extracted in 1957 during the processing of 

this ore for its iron content. Similar deposits of magnetite 

containing fluorapatite occur in Nevada but tonnages are 

not large and fluorapatite contents are not high (Reeves 

and Kral, 1955; Shawe and others, 1962); fluorine was not 

recovered from these deposits. 

Fluorine content of Tertiary igneous rocks, although 

too low to be considered as a potential resource, may 

indicate fluorine-rich zones worthy of exploration. Shawe 

(1966, p. C210, table 2) listed several areas in this region 

where Tertiary volcanics contain unusual amounts of 

fluorine. The rocks are porphyritic rhyolite and topazbearing rhyolite from hypabyssal bodies, rhyolite and 

topaz-bearing rhyolite flow rocks, and rhyolitic tuffs. The 

fluorine content of these rocks ranges from 1,200 to 17,500 

ppm (0.12 to 1.75 percent). Coats, Goss, and Radar (1963, 

p. 942, fig. 1) outlined several areas in this region where 

Cenozoic silicic volcanic rocks contain fluorine in the 

range of 1,000-5,000 ppm. 

DESCRIPTIONS OF INDIVIDUAL DISTRICTS AND DEPOSITS 

NEVADA 

BROKEN HILLS 

The Broken Hills fluorspar district is in the wedgeshaped northeastern part of Mineral County and is 70 

miles ( 110 km) southeast of Fallon, the nearest railroad 

point. 

All rocks exposed in the Broken Hills district are Tertiary volcanics, mainly rhyodacite to andesite flows, tuffs, 

and breccias and rhyolite and quartz latite welded tuffs 

(Ross, 1961). Limestone beds that constitute a possible 

host for fluorspar deposits are present in the dominantly 

volcanic Excelsior Formation of Triassic(?) age just west 

of the district. The district is cut by a series of northeast- to 

north-trending faults, most of which have accompanying 

zones of hydrothermal alteration. Few, however, have been 

mineralized with fluorite, and only one fault zone is significantly mineralized. 

For more detailed descriptions of the district see Thurston (1946), Matson and Trengove (1957), Ross (1961), and 

Archbold (1966). 

One mine, the Baxter or Kaiser, has yielded significant 

fluorspar, and the following discussion mainly concerns 

this mine. The Baxter mine was in almost continuous 

operation between 1928 and the time of its exhaustion in 

1957, producing more than 200,000 tons of acid- and 

metallurgical-grade fluorspar (Archbold, 1966, p. 10). The 

mine is closed and is considered to be mined out (Horton, 

1961, p. 14). 

The volcanic rocks in the vicinity of the Baxter mine are 

strongly faulted, brecciated, silicified, and hydrothermally altered. Much of the wallrock is altered beyond 

recognition of its original composition. According to 

Archbold (1966, p. 12), "All the fluorite veins are in 

Tertiary rhyolite that unconformably overlies weakly 

metamorphosed sedimentary and volcanic rocks 

presumed to be of Mesozoic age. The rhyolite is overlain by 

Tertiary volcanic rocks of intermediate composition." 

Small amounts of unaltered porphyry (quartz monzonite?) can be found on some dumps of the Baxter mine. 

This porphyry may be from narrow dikes that Thurston 

(1946, p. 2) reported to be common in the area. Thurston 

(1946, p. 2) also reported that there is no apparent relation 

between these dikes and the fluorspar mineralization. 

The fault zone that has been significantly mineralized is 

called the main vein; it strikes N. 40° E., dips an average of 

50° northwesterly, and has numerous bifurcations which 

trend north to northeast. The fault zone bearing the main 

vein is undulating and pinches and swells within short 
44 GEOLOGY AND RESOURCES OF FLUORINE 

distances, varying in width from 2 feet (0.6 m) at places on 

the 400-level to 18 feet (5.5 m) at the surface. 

The main vein is an aggregate of independent seams and 

masses of fluorspar 3 inches (7 .5 em) to 1 foot (30 em) wide. 

From published descriptions the main vein apparently is 

made up of a series of connected lenticular pipelike bodies 

in the plane of the fault (fig. 18). Fluorspar did not extend 

far below the 700-level of the Baxter mine, and along much 

of the vein it did not extend below the 400-level. Ore mined 

near the surface averaged 5 feet ( 1.5 m) in width and was as 

much as 9 feet (2. 7 m) in width. On the 300-level ore mined 

averaged 1.5 feet (0.5 m) in width and was as much as 5 feet 

(1.5 m) (Thurston, 1946, p. 3). Early mining was for ore 

containing more than 85 percent CaF2, and Thurston 

(1946) considered only material of this grade as ore. Kaiser 

Corporation's portion of the total production, on the 

other hand, averaged 46 percent CaF2• 

Fluorspar occurs as lenses, veinlets, and breccia cement 

within the fault zone. Layering and crustification with 

botryoidal and mammillary structures are normal. Judged 

from material left on the dumps, the fluorite was either a 

clear, pale-green or light-violet fibrous and columnar 

variety or a gray fine-grained variety intimately intergrown with chalcedony. Brecciated fluorite cemented by 

later fluorite or chalcedony is common, and slickensides 

along fluorspar seams are widespread. Intercalated with 

the fluorite are layers of chalcedony and minor layers of 

manganese oxide and "mountain leather," a fibrous 

mineral reported by Thurston (1946, p. 3) to be a member 

of the palygorskite group. 

Laser probe analyses of pure fluorite from the Baxter 

mine show only trace amounts of barium, manganese, and 

strontium common to almost all fluorite. Veinlets of 

brown chalcedony in silicified and altered country rock 

and minor gray breccias in the fluorspar contain trace 

amounts of zinc, arsenic, antimony, lead (up to 1,500 

NE 

Surfa 

_____ _.. 

0 500 FEET 

0 100 METRES 

ppm), and silver (up to 30 ppm). Manganese oxides present in the fluorspar also contain trace amounts of lead 

and silver. 

The Broken Hills mine, in the eastern part of the Broken 

Hills district, in addition to production of fluorspar, has 

had minor production of silver and lead that came from 

quartz-filled fissure veins and stockwork lenses in volcanic rocks (Ross, 1961, p. 81). 

QUINN CANYON RANGE 

Fluorite occurs at several locations in the Quinn Canyon Range, Lincoln and Nye Counties (fig. 19). Past production of fluorspar has been small, 200 tons from the 

Rainbow prospect in 1945-46 and about 14 tons that 

contained 50 percent CaF 2 from the Nyco mine by Wah 

Chang Corp. prior to closure of the Tern Piute mill 

(Horton, 1961, p. 18). Two areas are currently ( 1972) being 

mined-the Steel property by Lee Fennison, Panaca, Nev., 

and the Mammoth property by the Adaven Mining 

Company. Both operators are trucking their ore to the mill 

at Caliente, Nev., 100 miles (160 km) to the east. For more 

detailed descriptions of the geology and mineral deposits 

of the Quinn Canyon Range see Sainsbury and Kleinhampl (1969). 

In the Quinn Canyon Range fluorspar occurs in limestone and volcanic rocks in the vicinity of intrusive rocks. 

The deposits in the volcanic rocks are similar to the 

deposits in the Broken Hills district, Nevada, described 

above. The fluorspar deposits in limestone are diverse 

types of replacement bodies, fracture fillings, and veins 

characterized by presence of chalcedony and by layering. 

Sedimentary rocks of early to middle Paleozoic age and 

tuffaceous sedimentary and volcanic rocks of Tertiary age 

make up the country rock of the Quinn Canyon Range 

(fig. 19). These rocks are intruded by a small hypabyssal 

quartz latite porphyry pluton in the south-central part of 

the area, by a medium- to coarse-grained granitic stock in 

--- ____ ........ 

/ / 

/ 

sw 

/_.:.__Outline of ore body L 

FIGURE lB.-Longitudinal projection along "main vein" of the Baxter (Kaiser) fluorspar mine, Broken Hills district, Nevada (from Matson 

and Trengove, 1957, fig. 4). Black indicates mined-out areas. Horizontal lines show mine levels. 
38.15' 

I 

( 

! 

I 

\ 

\ 

Ely 

0 

NEVADA-UTAH-OREGON-CALIFORNIA-ARIZONA 

\ 

EXPLANATION 

D Quateroary alluvium 

~ Tertiary dike 

- Tertiary intrusive rocks 

D Tertiary volcanic and 

0 

tuffaceous sedimentary 

rocks 

Paleozoic sedimentary rocks 

!: >>>l Silicified rocks 

• Fluorspar deposit 

--- Fault - Dashed where concealed 

5MILES 

0 5 KILOMETRES 

T 

3 

N 

T 

2 

N 

FIGURE 19.-Map of the Quinn Canyon Range, Nevada, showing locations of fluorspar deposits (from Sainsbury and Kleinhampl, 1969, 

Pl. 1). 

45 
46 GEOLOGY AND RESOURCES OF FLUORINE 

Veins along fractures, in which fluorite and quartz 

form relatively coarse-grained intergrowths. 

Irregular, relatively high-grade replacement deposits 

in limestone in which fluorite is intergrown with 

silica, both irregularly and rhythmically, to form 

layered ores ("coontail" or "banded" ores), as at the 

HiGrade and Mammoth deposits. Locally these replacement bodies are separated from or extend well 

out from dikes and are thus distinguishable from 

the other class of high-grade replacement deposits 

described under 1, above. 

the north-central part of the area, and by numerous dikes 3. 

and sills of fine- to medium-grained dacitic to rhyolitic 

porphyry and andesite (fig. 19) (Sainsbury and Klein- 4. 

hampl, 1969, p. C3). The Paleozoic formations, composed 

mainly of limestone and dolomite, generally correlate 

with those assigned to the miogeosynclinal carbonate 

assemblage of the eastern Great Basin (Sainsbury and 

Kleinhampl, 1969, p. C3). The oldest Tertiary unit, of 

local extent only, consists of conglomerate and minor 

interbedded freshwater limestone. Volcanic rocks of 

Oligocene and Miocene age cover an extensive area of the 

Quinn Canyon Range (fig. 19). These rocks are rhyolite, 

rhyolitic to quartz latitic welded tuffs, and minor andesitic flows and breccias intercalated with some tuffaceous 

and sedimentary strata. 

The deposits in volcanic rocks are less diverse, and only 

two main types are recognized: {1) well-defined fissure 

veins filled with nearly pure coarsely crystalline fluorite. 

These veins are bordered by argillized wallrocks containing noticeable to abundant disseminated pyrite (Nyco 

mine); (2) large tabular fluorite deposits. Fluorite occurs 

irregularly as discrete but discontinuous veins and veinlets, commonly intergrown with jasperoid, throughout 

large tabular strongly silicified zones and fractured zones 

in volcanic rocks. The rocks in the outer portions of the 

altered zones contain disseminated pyrite. 

"Many of the mineral deposits are localized along the 

contacts of light-colored rhyolitic to dacitic porphyry 

dikes" (Sainsbury and Kleinhampl, 1969, p . C4). Wallrock alteration consisted of silicification of the carbonate 

sedimentary rocks and silicification and pyritization of 

volcanic rocks. Several large altered zones are shown in 

figure 19. Not all these silicified zones contain fluorspar. 

The Quinn Canyon Range is made up of several 

structural blocks bounded in part by Basin-Range faults. 

The structural blocks in which Paleozoic sedimentary 

rocks are exposed consist of gently folded or homoclinal 

sedimentary sequences cut by high-angle faults and, in 

some areas, thrust faults. The volcanic rocks are not as 

complex structurally but nevertheless probably overlie 

and conceal major structural units in the older rocks 

(Sainsbury and Kleinhampl, 1969, p. C4). The major dikes 

of the area trend east to northeast and cut across the strike 

of Paleozoic and Tertiary units and across the trend of 

thrust faults and folds. Discrete mineralized alteration 

zones in parts of the Quinn Canyon Range also trend east 

to northeast. The disparate trend and also the relatively 

late development of alteration, mineralization, and dike 

formation suggested to Sainsbury and Kleinhampl (1969, 

p. C6) that the fluorite deposits may be related to a late 

structural and igneous event, not yet clearly identifiable. 

Fluorspar in the Quinn Canyon Range occurs in a 

variety of deposits. The following classification of fluorspar deposits in the Quinn Canyon Range is taken from 

Sainsbury and Kleinhampl ( 1969, p. C7). (Individual 

deposits mentioned are shown on fig. 19). 

l. Relatively small but high-grade replacement deposits 

in limestone along dike walls (Spar claims). 

2. Mixed fine-grained silica (jasperoid) and fluorite that 

have replaced shattered limestone and dolomite, 

commonly forming tabular, flat-lying deposits in 

which the bulk of the fluorite cements breccia frag· 

ments or coats vugs (Valley View and Bonanza 

claims, Crystal group). Some deposits are localized 

in shattered jasperoid zones along thrust faults 

(Jumbo and Horseshoe claims, Spar group). 

Fluorspar grade is related to type of deposit and type of 

fluorspar. A small breccia pipe, less than 50 feet (15m) in 

diameter, on the Valley View claim of the Crystal group 

contains about 35 percent CaF2, all fluorspar occurring as 

breccia cement (Sainsbury and Kleinhampl, 1969, p. Cll ). 

At the Mammoth property, a large silicified zone in 

limestone-fine-grained siliceous "jasperoid" -contains 

16-22 percent CaF2 and 70-74 percent Si02 whereas 

layered "coontail" ore contains 22-35 percent CaF2 and 

50-65 percent Si02 (Sainsbury and Kleinhampl, 1969, p. 

Cl3). Small fluorspar replacement bodies at the Spar 

group contain more than 90 percent CaF2 (Sainsbury and 

Kleinhampl, 1969, p. CIS). An area comprising about 

28,000 ft2 {2,600 m2) on the HiGrade group contains 

approximately 65 percent fluorite, the richest zones containing about 75 percent. Another area, about 6,000 ft2 (560 

m2) on the same group, contains by assay 72 percent CaF2 

(Sainsbury and Kleinhampl, 1969, p. Cl7). The HiGrade 

group consists of silicic replacement deposits in limestone and at least one shoot of layered "coontail" ore. 

Mineralogy of the fluorspar deposits is simple: fluorite, 

quartz, jasperoid, and pyrite, and, in limestone replacement bodies, abundant calcite. Color and form of fluorite 

differ among different types of fluorite deposits. Fluorite 

in replacement bodies in limestone is either coarsely 

crystalline, nodular, and grayish white, or fine grained, 

compact, and light purple. The fluorite in large pure veins 

in volcanic rocks is mostly light green to colorless; the 

fluorite in the "coontail" ore and that cementing 

brecciated jasperoid is colorless or white, and the fluorite 

that forms small cubes is very faintly green (Sainsbury and 

Kleinhampl, 1969, p. ClO). 
NEVADA-UTAH-OREGON-CALIFORNIA-ARIZONA 47 

UTAH 

SPOR MOUNTAIN 

The Spor Mountain fluorspar district, described in 

detail by Staatz and Osterwald (1959), is in the southwest 

part of the Thomas Range in central Juab County about 

100 miles (160 km) southwest of Salt Lake City, Utah. 

Initial fluorspar production was in 1943, but large production did not occur until the late 1940's. More than 

100,000 short tons of fluorspar was produced in the period 

1943-56, (Staatz and Carr, 1964, p. 143). Following 

inactivity, the district recently (1971) has been revived as a 

result of the increased fluorspar market. 

Exposed rocks range in age from Early Ordovician to 

Pleistocene. Most of the district is underlain by a thick 

sequence of apparently conformable rocks, chiefly carbonates, of Paleozoic age. Silurian and Ordovician dolomites are the chief fluorspar-bearing units. Tertiary volcanic rocks that locally overlie the Paleozoic rocks are 

latite, dacitic tuff, quartz latite, volcanic breccia, lapilli 

tuff, quartz latite tuff, rhyolitic water-laid tuff, and topazbearing rhyolite. Dikes and plugs of breccia, rhyolite, and 

quartz latite intrude the Paleozoic rocks, commonly along 

faults. Gravels and marls of the Lake Bonneville Group 

were deposited during Pleistocene time in the region surrounding the Thomas Range. 

The Spor Mountain fluorspar deposits, though 

occurring dominantly in Paleozoic sedimentary rocks, are 

arbitrarily classified as associated with Tertiary volcanic 

rocks because of evidence of genetic relation to the topazbearing rhyolite. Near the fluorspar deposits, very large 

beryllium-bearing deposits in Tertiary volcaniclastic 

rocks contain about 5 percent fluorite (Staatz, 1963; Shawe, 

1968). 

The Paleozoic sedimentary rocks and the volcanic rocks 

have been tilted and now strike northeast and dip northwest. These consistently dipping rocks are cut by hundreds 

of faults belonging to at least five sets: (1) northeasttrending thrusts; (2) northeast-trending normal and highangle reverse faults; (3) northwest-trending faults; (4)easttrending faults; and (5) north-trending faults. 

According to Staatz and Osterwald ( 1959, p. 1-2), 

"Fluorspar deposits are of three types: oval to irregular 

pipes, veins, and disseminated deposits. The pipes, which 

show considerable range in shape and size with depth, 

have produced more than 99 percent of the ore• • •. [They] 

show evidence of two chief types of structural control: 

faults and intrusive breccia bodies." Ore pipes formed 

mainly by replacement along shattered zones in dolomite 

or volcanic rocks. 

The ore consists of 65-95 percent of fluorite with montmorillonite, 

dolomite, quartz, chert, calcite, and opal as impurities. The fluorspar 

closely resembles a brown, white, or purple clay and forms either pulverulent masses or boxworks. With depth the grade of the ore commonly 

decreases, and masses of montmorillonite, chert, or quartz and dolomite 

have been found in increasing abundance in some deposits. 

The fluorspar ore contained 0.003-0.33 percent U, 

according to analyses of numerous samples, and uranium 

grade varied considerably from place to place. 

Staatz and Osterwald (1959, p. 2) concluded that the 

fluorspar ore 

formed from fluorine-rich fluids, containing minor amounts of 

uranium, which were derived from the magma that formed the topaz-rich 

rhyolites of the Thomas Range during the last stages of volcanism. These 

fluids rose along faults and replaced shattered zones in the dolomite. 

Introduced elements other than fluorine and uranium were probably 

obtained from rocks underlying the deposits. 

ARIZONA 

CASTLE DOME 

The Castle Dome district lies along the southwestern 

edge of the Castle Dome Mountains, Yuma County, in 

the southwest comer of the Kofa Game Range, and is 

bounded on the west and south by the Yuma Proving 

Grounds. From the time of its organization in 1863 until 

1949 the district produced 17,726,93 7 pounds of lead and 

459,321 ounces of silver, mostly during the early part of 

the period. According to Wilson (1933, p. 87): 

The first important mining of fluorspar, which is a plentiful gangue 

mineral at Castle Dome, began in 1902. During 1902, 1903, 1904, 1908, 

1909, and 1913 carefully hand-sorted crystals and pure screening from 

the De Luce claims were shipped to the Riverside Portland Cement 

Company's plant at Riverside, California, to be used as a flux in producing cement clinker. 

The area was also active during World War I; fluorspar 

production from the district in 1902-17 exceeded 1,000 

tons (Wilson, 1950). Since then production has been small 

and intermittent. For detailed descriptions of the district 

see Wilson (1933; 1951). 

Country rocks in the Castle Dome district are wellbedded, weakly metamorphosed shale of probable 

Cretaceous age and diorite porphyry of Cretaceous(?) age 

(Wilson, 1951, p. 99). The shale rests unconformably upon 

granite and is faulted against schist, both of probable 

Precambrian age (Wilson, 1951, p. 99). These lithologies 

make up only a small part of the Castle Dome Mountains, 

the major part being volcanic rocks of probable Tertiary 

age (Wilson, 1933, p. 81). This volcanic pile includes 

about 2,000 feet (600 m) of rhyolites, andesites, tuffs, and 

obsidians and in places is overlain by several hundred feet 

of Quaternary(?) basalt. Locally, hypabyssal bodies of 

rhyolite porphyry have intruded the extrusive rocks; the 

fluorspar deposits appear to be related to these. The 

Cretaceous sedimentary rocks, host for argentiferous 

galena-fluorite veins, are dominantly greenish-gray shales 

and impure cherty limestones. Wilson (1933, p. 80) also 

reported locally abundant maroon shales, fairly pure limestones, brown arkosic sandstones, quartzites and 

conglomerates. Crosscutting the Cretaceous sedimentary 

. rocks is a remarkable and pervasive swarm of dikes of 

diorite and rhyolite composition. Wilson (1933, p. 82) 

indicated that the diorite dikes are older than the lavas and 

; the rhyolite dikes are younger. Alteration consisted of the 
48 GEOLOGY AND RESOURCES OF FLUORINE 

development of sericite and pyrite metacrysts throughout 

the rhyolite porphyry and in the Cretaceous sedimentary 

rocks, and in diorite in contact with the rhyolite porphyry 

dikes. 

Almost all structural elements in the Castle Dome district strike north to northwest. These include range-front 

faults and other faults, mineralized veins, the diorite and 

rhyolite dikes, and the folded Cretaceous sedimentary 

rocks. In the vicinity of the Castle Dome district the volcanics form a broad anticline plunging east. 

Fluorspar in the Castle Dome district occurs in argentiferous galena-fluorite veins. Gold-quartz veins and silverbearing manganese oxide veins are common in surrounding parts of the Castle Dome Mountains. The 

argentiferous galena-fluorite veins occupy north- to 

northwest-trending steeply dipping fault zones that cut 

the Cretaceous sedimentary rocks and the diorite and 

rhyolite porphyry dikes. Most mineralization occurred in 

altered zones around the rhyolite porphyry, and the veins 

are best developed where diorite porphyry makes up one or 

both of the vein walls. Although most are less than 5 feet 

(1.5 m) in width, veins as much as 12 feet (3.7 m) in width 

have been reported (Wilson, 1933, p. 83), and most veins 

are continuous for great lengths, some as much as 5,000 

feet (1,500 m). 

The argentiferous galena-fluorite veins are largely 

fissure fillings and cemented breccias in which layering 

and crustification of the gangue minerals are common. 

Gangue consists mainly of layers of coarsely crystalline 

varicolored fluorite, coarsely crystalline calcite, and black 

calcite that are cut by veins and veinlets of bladed to 

massive barite and chalcedony. Several veins in the district 

are composed entirely of the gangue minerals occurring as 

described above. Where present, galena forms sheetlike 

masses or irregular veinlike bodies in the fluorite or 

calcite. In places, veins consist of nearly solid masses of 

galena up to 8 feet (2.5 m) thick (Wilson, 1933, p. 83). 

Other vein minerals are hydrozincite, smithsonite, 

wulfenite, vanadinite, mimetite, aragonite, gypsum, 

anglesite, cerussite, and other lead oxides. Galena is the 

only sulfide mineral that has been noted. No silver 

minerals have been recognized even though the galena 

contains as much as 30 ounces silver per ton. 

Fluorspar deposits like those at Castle Dome are characterized by coarsely crystalline fluorite of high purity. 

Silica contamination does not affect the quality of the 

mined product, although lead contamination might. Most 

of these deposits may be related to Tertiary volcanism and 

many appear to be physically restricted to the volcanic pile 

with which they are associated. However, in districts like 

Castle Dome the source of the mineralizing solutions 

evidently was much deeper than the surface volcanics, and 

ascent of these solutions was controlled by major regional 

structures. Although fluorite is considered to be a gangue 

mineral at Castle Dome, as it is in most deposits of this 

type, it is plentiful enough to be considered as a source of 

fluorspar, either as the major product or as a coproduct. 

OTHER DEPOSITS 

Several fluorite, barite, and manganese oxide deposits 

occur in an east-northeast-trending zone along the 

southern end of the Harquahala Mountains, the northern 

end of the Big Horn Mountains, and through the Vulture 

Mountains. Production of fluorspar has been minor and 

mainly from the Snowball deposit in the Harquahala 

Mountains and from deposits in the eastern part of the 

Vulture Mountains (Van Alstine and Moore, 1969). 

Varying amounts of quartz, chalcedony, calcite, black 

calcite, barite, fluorite and manganese oxides are present 

in the deposits. Iron oxides, malachite, and trace amounts 

of gold are widespread. Layering, crustification, druses, 

and vugs characterize the deposits. Country rocks are 

granite, gneiss, schist, limestone, basalt, and volcanic 

agglomerate. The deposits are generally localized along 

northwest- or east-northeast-trending fracture systems as 

pods, short veins, and breccia fillings; deposits in basalt 

are made up of numerous stringers and pods spread 

through diffuse breccia zones. In the vicinity of the Snowball deposit, fluorite-rich deposits form horizontal layers 

consisting of cavity fillings and breccia cement in volcanic 

agglomerate. Two trench samples across a fluorspar 

breccia zone at the Snowball deposit indicate a grade of 72 

percent CaF 2 across a width of 4 feet ( 1.2 m), and 36 percent 

CaF 2 across a width of 12 feet (3. 7 m). 

COLORADO-NEW MEXICO-WESTERN 

TEXAS-SOUTHEASTERN ARIZONA 

By R. G. WoRL, W. R. GRIFFITTS, and R. E. VAN ALsTINE 

Fluorspar deposits are plentiful in Colorado and New 

Mexico, States that rank third and fourth, respectively, in 

total fluorspar production, following Illinois and 

Kentucky. Fluorspar production in Colorado began about 

1873 in the Jamestown district, Boulder County, and near 

Evergreen, Jefferson County. Almost 90 percent of the subsequent production has come from six districts: Northgate 

(Steven, 1960), Jamestown (Goddard, 1946), Browns 

Canyon (Van Alstine, 1969), Poncha Springs (Van Alstine, 

1964; Russell, 1947?; 1950), Wagon Wheel Gap (Van 

Alstine, 1964; Steven, 1968), and St. Peters Dome (Steven, 

1949). Production has been intermittent in most districts 

and reached a peak in 1944 when 65,209 tons of concentrates was shipped. Total shipments of fluorspar from 

Colorado through 1970 have amounted to about 1.3 

million tons, or about 10 percent of the fluorspar produced 

in the United States since records of production were 

started in 1880. Most of the concentrates have been shipped 

to the steel industry at Pueblo, Colo., to chemical, 

aluminum, and ceramic plants in other States; and to U.S. 

Government stockpiles. By 1963 shipments decreased to 
COLORADO-NEW MEXICO-WESTERN TEXAS-SOUTHEASTERN ARIZONA 49 

less than 10,000 tons, and only the Jamestown district was 

active. During 1969 an enlarged Northgate mine and mill 

began operation and produced concentrates for a new 

pelletizing plant at Cowdrey, Colo. 

The grade of Colorado deposits that have been worked 

ranges from about 20 percent to more than 75 percent 

CaF 2; most deposits were opened by underground 

workings, but some of the lower grade but larger ore 

bodies were mined in opencuts. Deposits are as much as 45 

feet (14m) thick and 2,600 feet (800 m) long in the Browns 

Canyon district, and opencuts on a vein zone in the Northgate district have been developed over a length of about 

4,400 feet (1,350 m) (Steven, 1960, p. 395). Fluorspar is 

mined below a depth of 1,400 feet (430 m) in the 

Jamestown district. 

Many other localities in Colorado have produced a little 

fluorspar, mostly from small veins (Cox, 1945) A 

pegmatite in the South Platte district, Jefferson County, 

yielded a little fluorspar as a byproduct of feldspar mining. 

Fluorite is present as a gangue mineral in various metalliferous deposits of gold, lead, zinc, tungsten, 

molybdenum, beryllium, and thorium (Van Alstine, 

1964 ), and extensive mine dumps and piles of mill tailings, 

such as those with fluorite in and near the Cripple Creek 

district, represent a possible future source of fluorspar. 

Topaz has not been an industrial product in Colorado 

or New Mexico, and most of the known deposits are too 

small or of too low grade to offer much promise. The 

mineral is a prominent component of hydrothermally 

altered rock in the molybdenum mines near Climax 

(Wallace and others, 1968) and Henderson (White and 

MacKenzie, 1973), Colo., and might thus become a byproduct of molybdenum mining at those or similar deposits 

in the region. The large tonnages of rock processed in the 

concentrators could yield significant amounts of topaz, 

even with a low content in the raw ore. 

Fluorspar mining began in New Mexico in the early 

1880's in the Burro Mountains and Gila districts. 

Production reached a peak in 1944 when 43,000 tons of 

fluorspar was marketed. Fluorspar has been produced in at 

least I 0 counties of New Mexico, with a total yield of about 

650,000 tons. Of the total, about one-third came from the 

Zuni Mountains district, Valencia County (Williams, 

1966, p. 4), nearly half originated in Grants County, 

coming from deposits in the Burro Mountains district, the 

Gila district, and the Cooks Peak.district, and most of the 

rest came from the Fluorite Ridge district, Luna County. 

Most of the fluorspar deposits in Colorado, New 

Mexico, western Texas, and southeastern Arizona are of 

Oligocene or younger age-younger than the latitic and 

rhyodacitic rocks of the great Sierra Madre Occidental 

volcanic field that occupies much of western Mexico and 

extends northward into New Mexico. 

General aspects of the types of fluorspar deposits in the 

region are discussed below. Fluorite-bearing deposits of 

Precambrian age were formed in a plutonic environment 

and have as their most widespread representatives the 

fluoritic pegmatites of the Llano area, Texas, the Petaca 

and other districts of New Mexico, a broad area in 

Douglas, Teller, and Park Counties, Colo., and an area 

east of Laramie, Wyo. Most of the pegmatites contain 

rather coarse-grained purple, green, and pink or creamcolored fluorite in the inner parts of moderately well 

developed zones. Associated minerals are red microcline, 

gray quartz, plagioclase, a black mica or amphibole, 

topaz, beryl, and a variety of rare-earth minerals including 

yttrian fluorite. A carload of fluorspar was reported to 

have been shipped from pegmatites in Douglas County, 

Colo., as a byproduct of feldspar mining, and another carload was a byproduct of pegmatite mining operations in 

Wyoming, but the potential of pegmatitic fluorite 

deposits is small. The pegmatite deposits in the Petaca 

district, New Mexico, contain coarse green fluorite in their 

inner parts associated with pale microcline, plagioclase, 

and muscovite mica; the mica has been the main economic 

product. Rare-earth minerals, though present, are much 

less common than in the other fluoritic pegmatites. 

Fluorite deposits of Laramide or early Tertiary age are 

less widespread than either the Precambrian or the 

Oligocene and younger Tertiary fluorite deposits. 

Laramide deposits apparently are restricted largely to the 

Front Range mineral belt in central Colorado, where the 

younger Tertiary fluorite deposits also are found. 

Environments of formation, structures, textures of 

mineral assemblages, and accessory mineral and metal 

contents differ among deposits of different ages and 

among deposits within age groups. This diversity of type 

is not so pronounced if only the major districts are 

considered. The Jamestown, Colo., deposits of middle 

Tertiary age contain fine-grained fluorite associated with 

minerals of lead, silver, gold, copper, and uranium in 

stockworks, pipelike bodies, and mineralized breccia 

zones, and represent a mesothermal type of mineralization (Lovering and Goddard, 1950, p. 43, 64, 258). 

Similar fluorspar deposits and associated alkalic 

intrusives occur in the Eagle Mountains, Tex.; Gallinas 

Mountains, N.Mex.; Iron Mountain, N.Mex.; Bear Lodge 

Mountains, Wyo.; and the Little Rocky Mountains, Sweetgrass Hills, Judith Mountains, and South Moccasin 

Mountains, Mont.; and fluorite occurs in trace amounts in 

and around many calc-alkalic intrusives throughout the 

West. These deposits are found in many rock types, 

although deposits of significant size occur in limestone or 

in shattered granitic plutonic rocks. Fluorite-rich deposits 

at Iron Mountain, N.Mex., are tactites in the contact zones 

of small silicic intrusives. 

Most other major districts in Colorado and New Mexico 

are of epithermal type and of later Tertiary age, commonly 

layered and crustified veins, but also mantos in sedimentary and volcanic rocks. They are localized by 
50 GEOLOGY AND RESOURCES OF FLUORINE 

geologically young steep faults and breccia zones in 

Tertiary volcanic rocks, Paleozoic and Mesozoic sedimentary rocks, and Precambrian silicic igneous and metamorphic rocks near the edges of uplifts or depressions. 

Most deposits of this type in Colorado are well-defined 

veins in plutonic and metamorphic rocks or in volcanic 

rocks, whereas those inN ew Mexico are commonly diffuse 

vein systems and mantos in calcareous country rocks, such 

as those at Sierra Cuchillo, described elsewhere in this 

report. Deposits in southeastern Arizona generally are 

veins in plutonic, metamorphic, or volcanic rocks. 

Deposits in Colorado include those in the Northgate, 

Browns Canyon, and St. Peters Dome fluorspar districts, 

and the deposits at Crystal, Dillon, Poncha Springs, and 

Wagon Wheel Gap. Notable deposits in New Mexico are 

those in the Gila, Burro Mountains, Anderson, Gold 

Hills, Steeple Rock, Sierra Caballos, Zuni Mountains, 

Fluorite Ridge, and Cooks Peak fluorspar districts, and 

deposits at Tonuco, Tortugas Mountain, Bishop Cap, and 

Sierra Cuchillo. In southeastern Arizona, similar deposits 

occur in the Tonto Basin, Aravaipa and Stanley areas, the 

Whetstone, Sierrita, and Chiricahua Mountains, and the 

Duncan and Copper Dome copper districts. Most formed 

at rather low temperatures and pressures near the earth's 

surface; warm or hot springs are associated with the 

deposits in some districts (Van Alstine, 1947, p. 461, 465). 

In the Browns Canyon and Poncha districts, Chaffee 

County, Colo., fluorspar deposits of late Tertiary age 

formed under near-surface hot-spring conditions from 

very dilute fluids (Van Alstine, 1969). Study of fluid 

inclusions indicates temperatures of deposition at about 

119°-168°C. The heat and fluoride are regarded as volcanic 

contributions to the mineralizing fluid. 

The epithermal fluorspar deposits are aggregates of 

fluorite, quartz, chalcedoney, barite, and various minor 

components. Many contain pale-green or white fluorite in 

grains 1-5 inches (2.5-12.5 em) long. Some of these are 

equant, but columnar or fibrous structures and 

successions of layers with different grain size, color, or 

structure are common. Most vein fluorspar shows slight to 

strong brecciation. Blocks of country rock and early 

fluorspar are cemented by late fluorspar or gangue 

minerals. Fine-grained fluorspar is present in large 

amounts in some districts in which coarse fluorspar also is 

found. 

Several Tertiary deposits in New Mexico are epithermal 

replacement deposits in upper Paleozoic sedimentary 

rocks, and some in Texas are in Cretaceous limestone. The 

deposits in Cretaceous limestone in Texas (Gillerman, 

1953; Underwood, 1963) are among the few in the Western 

United States that are bedding replacement deposits like 

those in the Illinois-Kentucky district. 

Fluorite is dispersed in Tertiary granite and occurs with 

topaz in small open veins in the Mount Antero area, 

Colorado. Like the vuggy veins in the Precambrian Pikes 

Peak Granite, these fissure deposits have yielded excellent 

crystals to mineral collectors but no industrially 

important fluorite or topaz. 

The intrusive rocks at Jamestown, Colo., at Mount 

Antero, Colo., and at similar occurrences are not closely 

associated with volcanic rocks but they yield radiometric 

ages of about 35m. y. and are thus nearly synchronous with 

the volcanism of the region; the intrusives may occupy 

deep parts of former (now eroded) volcanic vents. Even 

where deposits and volcanic rocks are widely separated, as 

at Northgate, Colo., and the Big Bend area of Texas, they 

nevertheless may be related genetically. 

A general discussion of the structural and geologic 

controls of fluorine mineral deposits in this broad region 

follows; the discussion encompasses northern Mexico as 

well as Colorado, New Mexico, western Texas, and southeastern Arizona in order to provide a more comprehensive 

review of the environment of the deposits. 

In the southern mountain region of Texas, New 

Mexico, southeastern Arizona and northern Mexico, the 

distribution of fluorite districts is related both to the great 

Sierra Madre Occidental volcanic field of Mexico and to 

regional tectonic features. Three major structures that are 

involved are ( 1) the Texas lineament, a belt of faults, folds, 

and intrusives which extends southeast from east-central 

Arizona, through El Paso and the Big Bend area to a 

terminus northeast of Monterrey, Mexico; (2) the Rio 

Grande trough, a series of structurally depressed basins 

that extends north from El Paso probably to the vicinity of 

Northgate, at the Colorado-Wyoming State line; and (3) a 

rather ill-defined zone of intense faulting that crosses the 

volcanic field in a northeast direction near the International boundary where the volcanic field enters southeastern Arizona. 

The Texas lineament is a complex structure with a 

history of instability extending onward in time at least 

from the Carboniferous. A submerged Paleozoic uplift is 

indicated by the transgression of formations of Carboniferous age across much older formations. The zone was 

also important in late Mesozoic time, as the Lower 

Cretaceous formations of Mexico terminate abruptly 

northward along a hinge line that lay along the lineament 

in southern New Mexico. Early Tertiary deformation 

resulted in tight folds and thrust faults, which appear to be 

the dominant structures in the eastern third of the 

lineament between the Big Bend and Monterrey, and have 

been mapped northwestward in Mexico to the International boundary near southwestern New Mexico. West 

of the Big Bend, these compressional structures are best 

developed south of the Border but they have been mapped 

in western Texas. There is a marked contrast near El Paso, 

where east-trending compressional structures predominate south of the Rio Grande and north-trending 

fault blocks predominate in the Franklin Mountains 

north of the Rio Grande. 
COLORADO-NEWMEXICO-WESTERNTEXAS-SOUTHEASTERNARIZONA 51 

Superimposed upon these older folds and thrust faults 

are many high-angle faults which bound blocks of both 

sedimentary and volcanic rock that may be raised or 

dropped several hundreds or even thousands of feet. Many 

of these, like the older structures, trend northwest, parallel 

to the lineament as a whole. Block faulting is best 

developed north of the border and west of the Big Bend. 

The faults farther southeast are persistent both laterally 

and vertically, but the displacements are commonly only a 

few feet and seldom exceed 100 feet (30m) (Temple and 

Grogan, 1963, p. 1041). The trends of these eastern 

fractures are less consistently northwest than are the 

western fractures, and most commonly are northnortheast, east-northeast, west-northwest, or northnorthwest. 

Small stocks and dikes of rhyolite are rather com1non 

in the lineament (as in the Sierra Blanca area) and are 

accompanied by intrusives of alkalic rocks between Sierra 

Blanca and the Big Bend. 

Fluorite-bearing deposits are found along most of the 

length of the Texas lineament, and are most numerous 

or largest near the two ends. The deposits in Mexico, east 

of the Big Bend, form a rather coherent though widespread group. Temple and Grogan (1963, p. 1051-1052) 

succinctly summarized the regional history that followed 

deposition of the Georgetown Limestone in Early Cretaceou~ time: 

1. Broad warping, development of joints, and development of an undulating surface with low relief determined by joint-controlled erosion. 

2. Deposition of the Del Rio Clay in Late Cretaceous 

time, largely in depressions in the erosion surface. 

3. Deposition of Buda Limestone and the Eagle Ford 

Shale. 

4. Folding along northwest-trending axes and renewed 

jointing. 

5. Block faulting, most prominent in the north-northwest-trending Boquillas Valley graben; intrusion of 

rhyolite and other siliceous rocks. 

6. Widespread fluorspar mineralization. 

The Mexican fluorspar deposits include crosscutting 

veins and mantos, or replacement deposits parallel to beds 

in limestone (Van Alstine and others, 1962). Both types 

are restricted to the Georgetown Limestone of Early 

Cretaceous age. The largest crosscutting veins are along 

contacts between rhyolite dikes and the limestone, or 

between segments of dikes and in the same structures as the 

dikes. The very large mineralized pipe at the Cuatro 

Palmas mine, Coahuila, lies in such a gap in a rhyolite 

dike (McAnulty and others, 1963, pl. 1). According to 

Temple and Grogan (1963) the vein deposits are largely in 

the upper part of the Georgetown Limestone, extending 

through a vertical range of several hundred feet. The 

mantos are found in the uppermost part of the Georgetown Limestone. They are tabular in vertical section and 

are elongated parallel to joints in the limestone. 

The same restriction of fluorite mineralization to the 

upper part of the Devils River Limestone (equivalent to 

Georgetown Limestone) is found in the quicksilver veins 

of the Terlingua district, Texas. Yates and Thompson 

(1959, p. 72) reported that the veins contain accessory 

fluorite only where the vein walls are Devils River Limestone. However, Gillerman (1953, p. 61-62) reported 800 

feet of Georgetown Limestone in the fluorite district in the 

Eagle Mountains, Tex., but the best host rock is the Finlay 

Limestone, which is below the Georgetown Limestone 

and separated from it by the intervening Kiamichi Formation. The mineralizing solutions must have had access to 

the Georgetown Limestone inasmuch as the reefs in the 

Grayson Formation, still higher in the section, are 

mineralized. There is little mention of systematic exploration of the limestone below the Georgetown in other 

districts, although McAnulty and others ( 1963) showed 

several small fluorite deposits in the Aguachile area in 

Edwards Limestone and one in the Kiamichi Formation; 

and in section they showed the large Cuatro Palmas 

deposit to extend downward through the Edwards Limestone (1963, pis. 1, 2). 

Farther northwest along the Texas lineament, formations of the Lower Cretaceous Series are poorly developed 

and are not known to contain fluorite. Toward the north, 

along the northwestern end of the Cretaceous Mexican 

geosyncline, owing to the change in sedimentary facies, 

the Georgetown Limestone is apparently absent from the 

stratigraphic section. Thus the only fluorite prospect 

reported by Albritton and Smith (1965) in the Quitman 

Mountains of Texas in this northern area is in rhyolite. 

Between El Paso, Tex., and Silver City, N. Mex., the 

structural relations of the fluorite deposits are rather 

complex, as the deposits are influenced by fractures of the 

Rio Grande trench system as well as those of the Texas 

lineament and the northeasterly fracture system. Structure 

is simpler still farther to the northwest. There are two 

rather ill-defined northwest-trending belts of fluorite 

mineralization in this westernmost area, separated from 

one another by 12-25 miles (20-40 km) of barren ground 

consisting of gravel-filled basins and hills of volcanic 

rocks. In the northeastern belt, the most westerly deposits 

commonly strike northwest along faults that parallel the 

lineament. Similarly, most of the deposits in the western 

part of the southwestern branch of the Texas lineament are 

in the northwest-trending fractures that are so common in 

the lineament. Farther eastward along the northeastern 

belt north-trending fractures become prominent as controlling structures for the fluorite mineralization, 

reflecting the fracturing associated with the Rio Grande 

trough. Northeast- and east-trending veins also are present 

and probably resulted from left-lateral movement along 

the Texas lineament. The northeast-trending veins lie 
52 GEOLOGY AND RESOURCES OF FLUORINE 

mainly in the area between the Lordsburg and Silver City 

districts, New Mexico, an area in which fluorite deposits 

are particularly plentiful and several moderately large 

mines have been opened. Such enhancement of mineralization at intersections of structures is well known to 

geologists both on this regional scale and on a smaller 

scale, affecting individual ore bodies, as at the Burro Chief 

fluorspar mine, Burro Mountains, N. Mex., one of the 

largest mines in the northeastern belt. 

Much farther south in Mexico, major fluorspar districts 

are also proximal to the Sierra Madre Occidental volcanic 

field, but they are restricted to regions in which the 

continuity of the volcanic rocks is broken by younger 

structures that bound the elongate areas of various rock 

units protrayed on geologic and tectonic maps of the 

Republic of Mexico. These areas are elongate in a northwesterly direction in east-central Durango, southwestern 

Zacatecas, and southwestern San Luis Potosi, and in a 

northerly direction in northern Guerrero. There is thus a 

southward persistence of the northwest-trending regional 

structures that are widespread in the Western United 

States; the structures in Mexico have controlled mineralization in a similar fashion. The fluorspar district in 

northern Guerrero is associated with high-angle faulting 

in a region of north-trending structures and at the south 

end of the great volcanic field. Situated as it is south of the 

northwest-trending transform fault zone, marked by 

recent volcanic rocks, this region may not be closely 

related structurally to the region farther north. The 

fluorspar district near Parral, southern Chihuahua, is in a 

rather small area of northeast-trending structures that lie 

athwart the northwest-trending structures that prevail 

regionally. The northeasterly trend at Parral is parallel to, 

and possibly similar in origin to, the broad structure that 

crosses the Sierra Madre volcanic field in and near southeastern Arizona. 

The Rio Grande trough is a general term for a series of 

basins that begins abruptly at the edge of the Texas 

lineament at El Paso and extends northward probably to 

Wyoming. Although the name gives prominence to one 

north-trending series of basins, the tectonic unit that 

concerns us here includes a much broader group of northtrending fault-block mountains, with their intervening 

basins, the whole reflecting major vertical movements. 

This tectonic unit, its parts very likely related in time and 

origin, is about 100 miles (160 km) wide in southwestern 

New Mexico, narrows to about 50 miles (80 km) at the 

latitude of Albuquerque, N. Mex., and then broadens to 

about 100 miles (160 km) again north of Santa Fe. In 

Colorado the tectonic relations are more obscure, as the 

Rio Grande trough cuts across the volcanic field of the San 

Juan Mountains and strongly developed northwesttrending fault blocks of the Front Range farther northeast. The two largest basins at the southern end of the 

tectonic unit, the Tularosa Valley to the east and the 

Jomada del Muerto to the west, die out northward. In part 

this termination resulted from displacement along faults 

in the set that passes northwest through the Guadalupe 

and southern Sacramento uplifts. As the San Andres 

Range dies out northward, the broader structural high of 

the Sacramento uplift east of the Tularosa Valley 

continues northward to join the southern end of the 

Sangre de Cristo Range. Fluorite deposits apparently are 

scarce along the eastern flank of the Tularosa Valley and 

the Sacramento uplift, but the deposit reported from 

Torrance County, N.Mex., is in the broad structural high 

that lies between the Sacramento uplift and the Sangre de 

Cristo Range. 

A belt of north-trending faults, nearly 20 miles (30 km) 

wide, lies along the western side of this part of the Rio 

Grande valley and is the westernmost part of the broad 

tectonic system. Faults of this belt form the eastern 

boundary of the Black Range and the southwestern 

boundary of the San Mateo Mountains and are found 

throughout the length of the intervening Sierra Cuchillo 

south nearly to the Cooks Range. Fluorite deposits are 

widespread in this belt, especially in the part north of 

Hillsboro. Fluorspar has been mined in the Sierra 

Cuchillo from typical epithermal veins in volcanic rocks 

and from replacement deposits in limestone of Paleozoic 

age, some of which are mantas without silicate gangue 

minerals and some are bedding-controlled replacement 

deposits with silicate gangue minerals (pyrometasomatic 

deposits). 

The northern part of the Rio Grande trough in 

Colorado is very complex structurally and has the basins 

in an en echelon series of northwest-trending fault blocks 

that make up the Front, northern Sangre de Cristo, 

Sawatch, Mosquito, and Gore Ranges, and the entire 

complex is crossed in a northeasterly direction by 

intrusives and ore deposits of the Colorado mineral belt. 

As at the south end of the trough in southern New Mexico, 

this intersection of tectonic units is the locus of a large 

number of fluorite deposits. Here also, high-angle faults 

have localized fluorspar deposits. The largest deposits are 

along the Arkansas River graben, at the faulted north end 

of the North Park basin, near caldera walls in the SanJuan 

Mountains, and near northwest-trending breccia reef 

faults, as at Jamestown. Possible northwest-trending belts 

of deposits may reflect structural control by faults with 

that trend, or may reflect greater exposure of older 

geologic features that resulted from uplift along the faults. 

The northeast-trending zone of intense faulting that 

crosses the Sierra Madre Occidental volcanic field near the 

International boundary is one of the major structures that 

influenced fluorite mineralization; it is both structurally 

complex and varied in its effects. It is rather sharply 

marked from the southwestern corner of New Mexico 

southwestward almost to Hermosillo, Sonora, Mexico, by 

the abrupt ends of segments of the volcanic field to the 
COLORADO-NEW MEXICO-WESTERN TEXAS-SOUTHEASTERN ARIZONA 53 

south_ North of this northeast-trending boundary the 

mountain ranges are rather short and commonly oriented 

north-northwesterly_ Fluorite deposits have been found in 

this region on both sides of the International border. To 

the northeast, along the trend of the zone, there is much 

less evidence of faulting, but fluorite deposits are particularly abundant where this zone crosses the Texas 

lineament and the major structures related to the Rio 

Grande trough between Lordsburg and Silver City. Some 

of the fluorite-bearing veins in these places strike northeast, an orientation that is less common than the northwest orientation prevalent elsewhere in the southwestern 

United States. 

The only important fluorspar district in New Mexico 

that is not in either the Rio Grande trough system or the 

Texas lineament is in the Zuni Mountains. This range is 

an upfolded and upfaulted block in which rocks of Precambrian age have been brought to the surface. It is 

elongated northwesterly and very likely is not closely 

related to other structures of the region, although a cluster 

of fluorspar deposits, the frontal fault of the Sacramento 

uplift, and a constriction in the main chain of basins of the 

Rio Grande trough in the Socorro area are on the southeast projection of the Zuni Mountain trend. The Zuni 

Mountains are part of a late Paleozoic high area; possibly 

their trend reflects the older structure. 

Most of the fluorspar districts in Colorado, New 

Mexico, western Texas, and southeastern Arizona have 

been idle during the last 15 years, because of the low price 

paid for the commodity and the competition of foreign 

mines_ Few deposits have been exhausted. With the 

increased prices of recent years, however, the known 

deposits will be reopened and new ore bodies will be found 

in most of the districts. The discovery in 1968 of a large 

deposit in the central Sierra Cuchillo, N. Mex., a range 

with very little earlier production, indicates that the minor 

districts cannot yet be disregarded as important sources of 

ore. Fluorspar is currently (early 1973) being mined in 

New Mexico in the Winkler anticline, Hidalgo County, 

and exploration in the State is under way in the Gila and 

Cooks Peak districts, in the Sierra Caballos, at Iron Mountain, at Holt and Whitewater Canyons, Catron County, 

and in the Bitter Creek area, Grant County. 

Good possibilities exist for the discovery of large lowgrade deposits of the replacement or manto type in sedimentary rocks in this region. Deposits of this type have 

been described in New Mexico and Texas. In New Mexico, 

various Paleozoic limestones are the host rock in the 

northern Sierra Caballos, Sierra County; the Magdalena 

Group of Pennsylvanian age is found at the Tortugas and 

Bishop Cap deposits, Dona Ana County, and at deposits in 

the Sierra Cuchillo, Sierra County (Rothrock and others, 

1946). Fluorspar is in Permian sandstones and siltstones of 

the Yeso Formation in the Gallinas district, Lincoln 

County (Perhac and Heinrich, 1964) and accompanies 

uranium minerals in the Todilto Limestone of Jurassic 

age near Grants, Valencia County. Lower and Upper 

Cretaceous limestones were replaced along three favorable 

horizons in the Eagle Mountains, Hudspeth County, Tex. 

(Gillerman, 1953) and in the Christmas MountainsCorazones Peak district, Brewster County, Tex. 

(McAnulty, 1967). Large, low-grade fluorspar deposits 

may form in certain sedimentary materials, for Tweto and 

others (1970, p. C69-C74) have described the Hammer 

deposit, Summit County, Colo., where Tertiary colluvium 

was mineralized by hot springs and then was broken up 

and diffused by Pleistocene landslides to form 

disseminated deposits. 

DESCRIPTIONS OF INDIVIDUAL DISTRICTS AND DEPOSITS 

COLORADO 

JAMESTOWN 

The Jamestown, Colo., fluorspar deposits are in the 

Front Range, in the central part of Boulder County 17 

miles (27 km) northwest of Boulder. Mining activity in the 

district began in 1874, and untill940 the major commodities were gold, lead, and silver. Fluorspar was a byproduct 

of lead and silver mining as early as 1874, with the first 

appreciable production coming during the period 1903 to 

about 1920. In 1940 two companies, Allied Chemical 

Corporation and Harry Williamson and Son, began largescale production of metallurgical- and acid-grade 

fluorspar. Allied Chemical Corporation's total production to 1972 of about 700,000 tons of acid-grade fluorspar 

(data published with permission) has been almost entirely 

from one mine, the Burlington, which has been in 

continuous operation since 1942. Harry Williamson and 

Son produced some fluorspar, mainly from the Emmett 

mine, and some from the Argo and Blue Jay mines, during 

1940-56. All deposits in the district have been developed by 

underground workings, several to depths of 400 feet (120 

m) or more; the Emmett mine, now closed, is developed to 

a depth of 1,000 feet (300m) and the Burlington to a depth 

of 1,400 feet (430 m), the present (1972) lower working 

level. For detailed geologic descriptions of the district see 

Goddard (1946), Lovering and Goddard (1950), and Kelly 

and Goddard ( 1969). 

Rock associations in the Jamestown district are characteristic of the Front Range, a Precambrian igneous and 

metamorphic complex containing numerous areas of 

high-level Laramide and middle Tertiary intrusions and 

related mineral deposits. The Precambrian rocks are Silver 

Plume Granite with scattered inclusions of metamorphic 

rocks, mainly biotite schist and hornblende gneiss (fig. 

20). These rocks are intruded by a Laramide stock of hornblende granodiorite composition about 4 mi2 (10 km2) in 

area, and a middle Tertiary stock of alkalic granite-quartz 

monzonite composition about 1 mi2 (2.6 km2) in area 

(Goddard, 1946, p. 12). The alkalic stock, intruded at the 
54 

40"10 

0 

0 

GEOLOGY AND RESOURCES OF FLUORINE 

'~ \'\ 

'· ' 

105"25' 

Area containing numerous 

breccia zones 

1 MILE 

1 KILOMETRE 

_,/ 

/ 

/ 

/ 

I I 

I i/ 

., ~ 'f 

\ !;"-.... 

J, " / 

~\~ \ 

EXPLANATION 

Argentiferous galena vein 

Tertiary alkalic granite-quartz monzonite 

Fluorspar vein 

Pyritic gold vein Tertiary granodiorite 

------- Gold telluride vein 

Breccia reef 

0 Precambrian rocks 

FIGURE 20.-Jamestown district, Colorado (modified from Lovering and Goddard, 1950, fig. 77, and Goddard, 1946, pl. 1). 
COLORADO-NEWMEXICO-WESTERNTEXAS-SOUTHEASTERNARIZONA 55 

north end of the granodiorite stock, is a composite 

intrusive. Fluorspar deposits at Jamestown are related to 

this alkalic stock. Alkalic dikes are common in the district; 

they were intruded late in the igneous cycle and in places 

are younger than the fluorite (Goddard, 1946, p. 12). 

Fluorite is a common mineral in the alkalic granite-quartz 

monzonite and also occurs in crosscutting silicified zones 

within the stock. Zones in which all rock types were altered 

to clay minerals, sericite, chlorite, and carbonates are 

common, and extend beyond known mineralized zones. 

Similar altered rock is common in the contact zone of the 

alkalic stock. Country rock alteration was minor in the 

contact zone of the granodiorite stock. 

James town is at the northeastern end of the Colorado 

mineral belt, a northeast-trending zone in which Precambrian basement structures and Laramide structures 

controlled the location of Laramide and Tertiary 

intrusives and mineralization. This part of the Front 

Range is characterized by a series of strong northwesttrending faults, called breccia reefs, of Late Cretaceous 

age. These were important in the localization of ore 

deposits in several districts (Lovering and Goddard, 1950, 

p. 237). Two significant breccia reefs cut the Jamestown 

district just west of the major fluorspar deposits. They 

contain minor amounts of clear fluorite; at places in the 

district pyritic gold veins and gold telluride veins radiate 

from breccia reefs. Localization of the major fluorspar 

deposits, however, probably was controlled by fractures 

forming breccia zones different from the breccia reefs and 

created by the forceful intrusion of the alkalic stock 

(Goddard, 1946, p. 13); the deposits were not localized by 

the breccia reefs. Fluorspar bodies in the Jamestown 

district are localized mainly in breccia zones and fissures 

that form radiating and ring fracture zones around the 

alkalic stock; fluorspar bodies also occur in fractures of 

regional northeast and northwest sets. 

The Jamestown mining district contains four types of 

mineral deposits characterized by argentiferous galena, by 

fluorspar, by pyritic gold, and by gold telluride; all are 

about the same age, and all are genetically related. Pitchblende is present in some deposits. Lovering and Goddard 

(1950, p. 260) pointed out a rough zonal arrangement of 

these deposits around the alkalic stock; the sequence of 

zones outward from the stock is argentiferous galena, 

fluorspar, pyritic gold, and gold telluride. 

Argentiferous galena occurs mainly in massive pipe like 

bodies, broken blocks, and individual grains scattered 

through fluorspar-bearing breccia zones, but also it occurs 

as massive lenses and disseminated grains in fluorspar and 

pyritic gold veins. 

Most of the fluorspar is found in veins and large breccia 

zones around the western and southern eC.ges of the alkalic 

stock. Minor fluorite also occurs in most pyritic gold and 

gold telluride veins within 1 mile (1.6 km) of the alkalic 

stock. Several generations of fluorite formed in the Jamestown district and most are separated by periods of 

brecciation. 

Pyritic gold veins occur throughout the district and cut 

all rock types, including alkalic granite-quartz monzonite. 

They are best developed outside the fluorspar zone and as 

far as 2 miles (3 km) from the alkalic stock. In mines where 

both pyritic gold and gold telluride veins are present, the 

gold telluride veins are demonstrably younger (Goddard, 

1946, p. 12). 

Most gold telluride veins are 1.5"'"'3 miles (2.5-5 km) from 

the alkalic stock. However, the Buena mine, mainly on 

gold telluride veins, is just outside the major fluorspar 

zone on the west side of the alkalic stock. Tellurides have 

been found in many fluorspar deposits and in pyritic gold 

veins. Gold telluride veins are not confined to the Jamestown district; they have wide distribution in the northeast 

part of the Colorado mineral belt (Kelly and Goddard, 

1969). 

The major fluorspar ore bodies are in breccia zones, best 

developed in Silver Plume Granite along the western 

contact of the alkalic stock. The breccia zones are hundreds 

of feet in diameter, irregular in shape, and not related to 

known fault structures. Fluorspar in the breccia zones 

occurs in nearly vertical pipelike bodies that in plan are 

irregular in shape but tend toward lenticular, and are 

10-100 feet ( 3-30 m) wide and as much as 500 feet ( 150 m) 

long (fig. 21). In the Burlington mine a vertical exposure 

N 

1 

0 

0 

EXPLANATION 

Fluorspar vein containing 

60-90 percent CaF 2 

17 

<J 

Fluorspar breccia containing 

30-60 percent CaF 2 

Breccia containing less 

than 30 percent CaF 2 

Silver Plume Granite, 

fractured and altered 

100 FEET 

25 METRES 

FIGURE 21.-Fluorspar deposit at the tunnel level of the Burlington 

mine, Jamestown district, Colorado (workings not shown). From 

Goddard (1946, pl. 8). 
56 GEOLOGY AND RESOURCES OF FLUORINE 

of one pipelike fluorspar body is more than 1,400 feet (420 

m). Commonly the fluorspar ore bodies consist of a lenticular central core of a breccia composed of 60-90 percent 

CaF 2 and minor wallrock, surrounded by an irregular zone 

of fluorite-bearing breccia containing 5-60 percent CaF 2 

(Goddard, 1946, p. 20). Large areas of breccia containing 

5-30 percent CaF2 are common. The fluorspar mineralized bodies are surrounded in most places by unmineralized but silicified breccia composed of altered wallrock. 

Fluorspar veins several inches to 20 feet (6 m) wide and 

150-1,000 feet (45-300 m) long are common around the 

southern and western edges of the alkalic stock, mostly in 

granodiorite. Goddard ( 1946, p. 20) reported that the veins 

commonly contain 60-85 percent CaF 2 . 

Silica content of Jamestown fluorspar, especially of 

low-grade ore, is relatively high. A high-grade concentrate is readily obtained by flotation methods as the 

fluorite is generally not intimately intergrown with quartz 

or chalcedony. Most silica present is in wallrock 

fragments. 

Many of the fluorspar ore bodies contain enough lead-, 

gold-, and silver-bearing sulfides to make saving of a 

sulfide concentrate potentially profitable. Goddard (1946, 

p. 20) reported two instances of Jamestown fluorspar 

yielding sulfide concentrates. At the Lehman mill in 1933 

a galena-pyrite concentrate containing 30 percent lead and 

0.28 ounce of gold and 3.6 ounces of silver to the ton was 

recovered from jigs and tables. At the Wano flotation mill 

in 1942 and 1943 a sulfide concentrate containing about 30 

percent lead and 20-30 ounces of silver to the ton was 

recovered. Copper has also been recovered. as a byproduct 

from Jamestown ore (Goddard, 1946, p. 20-21). Semiquantitative spectrographic analyses of 38 samples of 

fluorspar from the Burlington ore body, a pipelike body in 

a breccia zone, indicate an average of 33 ppm Ag, 3, 700 

ppm Ph, 4,850 ppm Ce, and 1,800 ppm Nd. Semiquantitative spectrographic analyses of 35 flourspar samples 

from the rest of the district, mainly from veins, indicate an 

average of 9 ppm Ag, 2,600 ppm Ph, 1,150 ppm Ce, and 580 

ppmNd. 

Fluorspar from breccia zones and veins alike is everywhere brecciated, and it exhibits at least two phases of 

fluorite and evidence of several events of brecciation. 

Generally the fluorspar ore consists of angular crystalline 

fluorite, sulfide fragments, and angular wallrock fragments, all less than an inch (2 em) in diameter, set in a very 

fine grained matrix of rounded and corroded fluorite, clay 

minerals, carbonate minerals, and quartz. In breccia zones 

the fluorspar material is as described above, but it encloses 

large blocks of altered wallrock as much as several feet in 

diameter. Most of the fluorite is crystalline, light violet to 

dark purple, and is commonly zoned. Fluid-inclusion 

studies (J. T. Nash, oral commun., 1970) of fluorite from 

the Jamestown district indicate homogenization temperatures in the range 350o_400°C. Fluid salinities are 

commonly high, 40 weight percent or more. Many fluid 

inclusions contain several "daughter" minerals. These 

data suggest that fluorite deposition took place from a 

hot, highly saline solution at high pressure. Pyrite, galena, sericite, and books of euhedral biotite, all fine 

grained, are disseminated through the fine-grained 

matrix. Sphalerite, chalcopyrite, tennantite, and enargite 

are locally present. Sulfides also occur as massive pipelike 

bodies in breccia zones and as massive lenses in veins. 

Chalcedony and hematite are locally present as a late 

breccia cement. Some low-grade fluorspar breccias contain abundant celestite, which also occurs with green 

fluorite in vugs. Ankerite, arfvedsonite, calcite, biotite, 

adularia, and purple fluorite crystals that display coarsegrained pegmatitic texture compose some fluorspar veins 

southwest of the alkalic stock. Minute grains of pitchblende have been identified in fluorspar from several deposits (Goddard, 1946, p. 19). 

The Jamestown fluorspar deposits are characterized by 

fluorite crystals, both massive and granular, in aggregates 

intergrown with the other minerals. Conversely, 

columnar-fibrous fluorite, monomineralic layering, and 

crustification are not present. The depositional sequences 

were complex; more than one mineral phase was deposited 

from each hydrothermal surge, in contrast to the monomineralic depositional phases of low-temperature layered 

fluorspar deposits. 

The alkalic magma was genetically related to, if not the 

ultimate source of, fluorine-bearing hydrothermal solutions that deposited the fluorite. The alkalic granitequartz monzonite contains 0.05 to 2.3 percent F (average 

0.27 percent) based upon analyses of 36 samples collected 

throughout the stock. Similar calc-alkalic or alkalic 

intrusives in receptive host rocks would be excellent 

exploration guides elsewhere, especially if they contained 

similar anomalous amounts of fluorine. 

The potential of the Jamestown fluorspar deposits is 

enhanced by the presence of large areas of mineralized 

breccia, albeit low grade, and possible byproducts of lead, 

silver, gold, and of rare-earth elements that are present in 

the fluorite. 

NORTHGATE 

The Northgate fluorspar district lies in the northeastern end of the North Park intermontane basin near the 

Colorado-Wyoming boundary line. Walden, Jackson 

County, Colo., is 10 miles (16 km) south of the district and 

Laramie, Wyo., is about 50 miles (80 km) east. A major 

paved highway between Walden and Laramie (Colorado 

127-Wyoming 230) passes through the district, as does a 

Union Pacific Railroad branch line originating in 

Laramie. 

Although prospectors for copper noted veins in the 

district as early as 1900, no fluorspar claims were staked 

until 1918 and there was no recorded production until 

1922. Colorado Fluorspar Corporation produced about 

15,000 tons of metallurgical-grade fluorspar between 1922 
COLORADO-NEW MEXICO-WESTERN TEXAS-SOUTHEASTERN ARIZONA 57 

and 1927 from the Fluorspar vein system. The district was 

then idle untill941 when the Western Fluorspar Corporation leased the Colorado Fluorspar Corporation holdings, 

and a 450 ton-per-day capacity sink-float mill was constructed by Defense Plants Corporation. This operation 

ceased in 1945 after about 115,000 tons of fluorspar had 

been produced from underground and open-pit operations on both the Fluorine and Fluorspar vein systems. 

During this same period about 700 tons of fluorspar was 

mined from the Camp Creek mine on the northern end of 

the Fluorine vein system by Kramer Mines, Inc. In 1950 the 

Aluminum Company of America acquired the Camp 

Creek property, but to date (1972) has produced no 

fluorspar. 

In 1951, Ozark-Mahoning Co. acquired control of most 

property on both vein systems, with the exception of the 

Camp Creek and Penber mines. Following construction of 

a 300-ton-per-day flotation concentrator in 1952, until 

operations ceased in 1959, Ozark-Mahoning produced 

fluorspar from three sources in the following proportions: 

70 percent from open pit, 18 percent from sink-float 

tailings, and 12 percent from mine development. OzarkMahoning Co. expanded their Northgate facilities in 1968 

to 650 tons per day capacity and also added a concentrate 

briquetting facility. Since this enlarged facility began 

operation, Ozark-Mahoning has been producing 

fluorspar from underground mine work along the 

Fluorspar vein system and from underground mine and 

open pit work along the Fluorine vein system. The following geologic description of the Northgatedistrictis largely from Steven (1960). 

Country rocks at Northgate are quartz monzonite and 

hornblende-biotite gneisses of Precambrian age; shales, 

sandstones and minor limestone of Mesozoic age; and 

arkose, tuffaceous siltstones and clays of the White River 

Formation of Oligocene age (Steven, 1960, p. 336). The 

bulk of the fluorspar occurs in veins within Precambrian 

quartz monzonite and within arkose of the White River 

Formation, and only minor fluorite occurs in faults in 

Mesozoic sedimentary rocks and in veins in Precambrian 

metamorphic rocks. Silicification and pyritization of the 

quartz-monzonite wallrock were common along the 

Fluorspar vein system, and argillization and silicification 

of the White River Formation were common along the 

Fluorine vein system. 

The dominant structural feature of the district is the 

Independence Mountain fault, an east-trending and 

northward-dipping reverse fault with a hanging wall of 

Precambrian rocks and a footwall of Mesozoic sedimentary rocks. This fault, which predates the White River 

Formation (Steven, 1960, p. 369), transects earlier 

Laramide structures and forms the abrupt north boundary 

of the North Park intermontane basin. 

Fluorspar occurs as veins in two parallel northwesttrending fault zones about 2 miles (3 km) apart that postdate the White River Formation. These fault zones are in 

the hanging wall of the Independence Mountain fault. 

The western (Fluorspar) vein system extends slightly more 

than a mile (1.6 km) northwest from the Independence 

Mountain fault and is mineralized throughout most of its 

length; the eastern (Fluorine) vein system extends more 

than 2 miles (3 km) and is mineralized also along most of 

its length, though sparsely in places. Fluorite was 

deposited through a vertical range of more than 1,050 feet 

(320m). 

In the Fluorspar vein system fluorspar occurs as veins 

and veinlets a fraction of an inch to a few feet (millimetre 

to a metre) in width, as breccia "cement" coating breccia 

fragments, and as breccia fragments, all in coarse-textured 

fault breccia. Commonly, ore-grade fluorspar occurs in a 

zone, up to 20 feet (6 m) wide, of broken and cemented 

blocks of wallrock and fluorspar (breccia) containing 

veins of nearly pure fluorspar along or near one or both 

edges. Assays of samples of the fluorite stringers run as 

high as 97 percent CaF2 (Steven, 1960, p. 399). The average 

for the vein zone for widths of 8-11 feet (2.4-3.4 m), 

however, runs between 40 and 50 percent CaF2, and the 

range is from 10 to 90 percent CaF2 (Steven, 1960, p. 399). 

Mineralogy of the fluorspar in the Fluorspar vein 

system is simple. Fluorite and chalcedony are the major 

minerals with some quartz and very minor barite, 

manganese oxides, and pyrite. Clay is common but is 

thought to be a weathering product of fine-grained fault 

gouge. Monomineralic layers ("bands"), crusts, and 

botryoidal layers with numerous drusy cavities are the 

characteristic forms of fluorite occurrence. Watercourses 

lined with fluorite are common. Columnar green fluorite, 

columnar honey-colored fluorite, crystalline purple 

fluorite, dense black fluorite, milky-white chalcedony, 

bladed barite, and manganese oxides occur in distinct 

layers where each layer is composed almost entirely of one 

mineral or form of mineral (fig. 22). A depositional 

sequence for the Fluorspar vein system is shown in the 

following table. Only the events marked "major" on the 

table occurred throughout the vein system; the others were 

of a local nature. 

Depositional sequence of fluorspar in the Fluorspar 

vein system, Northgate, Colorado 

[Listed in order of increasing age. X, period of brecciation; m, major] 

Thin coatings of chalcedony, honey-colored columnar-fibrous 

fluorite, and manganese oxides. 

X Gray to black siliceous fluorite, mainly as a breccia cement. 

mX 

Contains stringers of pyrite. Part of the wallrock alteration 

occurred during this stage. (Major.) 

Honey-colored columnar-fibrous fluorite in veins and as 

breccia cement. (Major.) 

X Alternating bands of gray siliceous fine-grained fluorite, white 

chalcedony and small stringers of barite and manganese 

oxide. 

X Siliceous fine-grained breccia with some stringers of barite. 

(Occurs throughout, but in places is very minor.) 
58 GEOLOGY AND RESOURCES OF FLUORINE 

mX 

Alternating bands of clear and purple crystalline fluorite, 

gray siliceous fluorite, and minor barite. 

X Gray siliceous breccia with stringers of pyrite. Mainly a 

dense black siliceous fluorite. Part of the wallrock alteration occurred during this stage. (Major.) 

mX 

X Columnar-fibrous green fluorite, white chalcedony, finegrained gray siliceous fluorite, and gray siliceous breccia 

in alternating layers. 

Fluid inclusion studies (J. T. Nash, oral commun., 

1970) of fluorite from the Fluorspar vein indicated homogenization temperatures of 130°-175° and salinities of 

0.1-3 weight percent. Fluid inclusions here are small and 

sparse. The data suggest that the mineralizing solution 

was a. hot springs type consisting of predominantly 

meteonc water. 

The Fluorine vein system is larger than the Fluorspar 

vein system and is as much as 70 feet (20 m) wide-but 

tends to be more diffuse and branching. The highest assays 

quoted by Warne (1947, p. 15-20) for sample widths of 

about 5 feet (1.5 m) are 70-80 percent CaF2• Mineralized 

rocks in the White River Formation contain about 30 

percent CaF2 for 15-foot (4.5-m) widths and between 20 

and 25 percent CaF 2 for 35-foot ( 1 0.5-m) widths. Where 

quartz monzonite constitutes the wallrock, vein material 

averages about 45 percent CaF 2 for widths of 25-30 feet 

(7.5-9 m), and vein material averages about 30 percent 

CaF2 for widths of 35-45 feet (10.5-14 m) (Warne, 1947, p. 

15-20). In the Fluorine vein system most of the fluorspar 

EXPLANATION 

1 Layered columnar-fibrous green fluorite 

2 Gray siliceous breccia with wallrock and fluorspar fragments and 

siliceous fluorite cement 

3 Columnar-fibrous honey-colored fluorite 

4 Gray fine-grained siliceous fluorite 

FIGURE 22.-Slab of fluorspar from the Fluorspar vein system, Northgate, Colorado, showing different types of fluorite. 

occurs as earthy masses and stringers in fine-grained fault 

breccia, and as fracture and space filling in arkosic beds of 

the White River Formation. Drusy cavities are common 

but massive veins of pure fluorite are not. The fluorspar 

consists mainly of fluorite and chalcedony with some 

quartz and manganese oxides. Montmorillonite, in many 

places intergrown or mixed with the fluorite and fault 

gouge, is common throughout, and crystalline calcite is 

common in mineralized arkose of the White River 

Formation. 

Pure fluorite from both vein systems contains trace 

amounts of barium, manganese, strontium, and yttrium as 

do fluorites elsewhere. Laser probe analyses also indicate 

that trace amounts of zinc, copper, and silver occur in 

manganese-oxide zones, in scattered places in some finegrained gray breccias, and in some minor columnar green 

fluorite layers. Molybdenum occurs in anomalous 

amounts in the wallrocks surrounding the Fluorspar vein 

and in places within the vein as described by R. G. Worl 

(U.S. Geol. Survey, 1970, p. A5). Ilsemannite, reported in 

parts of the Fluorspar vein system (Goldring, 1942), may 

be jarosite stained blue by molybdenum trioxide. The 

source of the molybdenum anomaly is molybdenite, 

widely disseminated through siliceous black material that 

is a submicroscopic intergrowth mainly of fluorite, 

chalcedony, and pyrite. This molybdenum-bearing 

material occurs as minor stringers and breccia fragments 

within the vein zone and as a pervasive stockwork of 

veinlets in the wallrocks around the fluorspar vein. The 

molybdenum-bearing material was the only vein material 

that penetrated the wallrocks away from major fractures. 

The Northgate fluorspar district is not closely 

associated with Tertiary volcanic rocks, but such rocks are 

present in the region and probably the deposits formed 

during the episode of middle Tertiary volcanism that was 

responsible for the volcanic rocks of the region. 

OTHER DEPOSITS 

Fluoritic pegmatites of Colorado are in or near the Precambrian Pikes Peak batholith. Pikes Peak Granite 

contains 4,040 ppm fluorine (average of 38 samples; Fred 

Barker, written commun., 1972), much of it as fluorite. 

Although the total tonnage of fluorite in the batholith 

may be very large, the concentration of the mineral is so 

low that little, if any, will ever be recoverable. This 

dispersed fluorite increases the fluorine content of ground 

water, in places to objectionable levels, causing mottled 

teeth in the Colorado Springs area. The Pikes Peak 

Granite contains, in addition to feldspars, quartz, and 

biotite, small amounts of the cerium minerals allanite and 

bastnaesite. The Pikes Peak Granite locally also contains 

veins of quartz or of quartz and feldspar that contain 

crystals of topaz, fluorite, amazonite, or other minerals 

that are of value to mineral collectors but not to industry. 

The main economic importance of the veins and 

pegmatites is as indicators of mobile metal and fluorine 
COLORADO-NEW MEXICO-WESTERN TEXAS-SOUTHEASTERN ARIZONA 59 

that somewhere in the area may be concentrated into 

minable deposits. 

A Precambrian topaz-quartz-sillimanite gneiss in the 

central part of the Front Range, in Jefferson and Clear 

Creek Counties just west of Denver, contains major 

amounts of topaz. This unit, part of a high-grade metamorphic gneiss and granitic plutonic complex, is 11-100 

feet (3.4-30 m) thick and crops out along strike for 7,000 

feet (2,150 m). Three composite chip samples of this unit, 

taken by Sheridan, Taylor, and Marsh (1968, p. 3-6), 

contain 67, 23, and 36 weight percent topaz and, 

respectively, 4.2, 3.9, and 2.2 weight percent rutile. Modal 

analyses of four samples of the topaz-bearing gneiss 

indicate by volume 5.5-68.2 percent quartz, 30.1-71.9 

percent topaz, 1.7-3.1 percent rutile, 18.2 percent 

sillimanite in one sample, 13.0 percent apatite in one 

sample, and trace amounts of zircon and muscovite. Rutile 

concentrates contain 0.05-0.15 percent Nb and 0.3-0. 7 

percent Fe as determined by semiquantitative spectrographic analyses. Sheridan, Taylor, and Marsh (1968, p. 7) 

suggested that the gneiss warrants investigation as an ore 

of rutile, especially because it might also yield a topaz or 

topaz-and-sillimanite product, which is salable as raw 

material for refractories and ceramics. 

NEW MEXICO 

BURRO MOUNTAINS 

The Burro Mountains district is in southwestern Grant 

County, 9-30 miles (14.5-48 km) southwest and south of 

Silver City. Fluorite was recognized in the mineral 

deposits in the area when mining of copper and turquoise 

began in the 1870's. Fluorspar was first mined there in the 

1880's for use as flux in the copper smelters. More 

significant fluorspar mining began at the Burro Chief 

mine in 1913 and continued with interruptions until the 

1950's. Information on the geology of the district was 

obtained from Gillerman (1953; 1964) and Rothrock, 

Johnson, and Hahn (1946). 

The Burro Mountains are geologically complex. An uplifted fault-block mass of crystalline rocks of Precambrian 

age is intruded by dikes and stocks and overlain by volcanic rocks of Cretaceous and Tertiary age. The crystalline rocks were separated into four blocks by three persistent northwest-striking faults that may be elements of the 

Texas lineament. In the fluorspar areas these faults are 

accompanied by northeast- and east-trending cross-faults 

and north-trending splits of the main faults. The fluorite 

is found along these north-trending minor faults. One 

deposit is in volcanic rock and the others are in granite and 

schist; the deposits formed during the region's Tertiary 

volcanism. Precambrian granite is the most favorable host 

rock; hence the deposits are associated spatially with 

granite and temporally with volcanism. 

The largest deposit, the Burro Chief, now within the 

Tyrone open-pit copper mine, is in a northeast-trending 

breccia zone that is 10-100 feet (3-30m) wide in granite. 

The deposit earlier had been opened by a shaft to a depth of 

700 feet (210 m). Four types of ore have been distinguished: (1) high-grade massive vein fluorspar containing 75....;90 percent CaF2; (2) soft fluorspar breccia containing 35-75 percent CaF2; (3) hard fluorspar breccia containing 50-90 percent CaF2; and (4) breccia and other lowgrade ore containing as much as 35 percent CaF2. Where 

unbrecciated, the fluorspar is clear, green, and moderately 

coarse grained. Clay and quartz are the most common 

impurities. The hard fluorspar breccia consists of an 

earlier variety with a green fluorite cement that is found in 

the upper part of the mine and of a later variety with a 

purple fluorite cement that is found throughout the ore 

zone. 

GILA 

The Gila fluorspar district in Grant County 

encompasses about 5 mi2 (13 km2) along the Gila River 5 

miles (8 km) upstream from the town of Gila. It was the 

locus of early fluorspar mining in New Mexico when the 

Foster mine was opened in the 1880's. Though small in 

area, the district has provided more than 4 7,000 tons of 

fluorspar (Williams, 1966). About 29,000 tons of this came 

from the Clum mine, the biggest producer during World 

War II. 

The fluorspar deposits are in latitic and andesitic rocks 

of the Datil Formation of Tertiary age. The ore deposits 

were formed along faults and breccia zones, mainly as 

open-space fillings, and minor replacement of the 

volcanic rocks. The rocks were strongly argillized in some 

places and quartz was deposited with fluorspar in and near 

the veins. Most veins strike north to north-northwest. The 

Foster vein strikes northeast and the Cedar Hill, Clum 

East, and Green Spar veins strike northwest. Persistent 

northwest-striking faults separate the volcanic rocks from 

the younger unmineralized Gila Conglomerate farther 

southwest and cut the volcanic rocks northeast of the 

mining district. The ore deposits have not, in general, 

been completely delimited. The Clum North ore body was 

at least 510 feet (155m) long, 150 feet ( 45 m) deep, and 6 feet 

(1.8 m) thick. The main ore body mined at the Foster mine 

was at least 280 feet (85 m) long, 130 feet (40 m) in vertical 

extent, and 3-8 feet (1-2.5 m) thick. The prospects for discovery of additional ore seem good. Mining may be prevented, however, if the canyon of the Gila River is flooded 

by a proposed dam. 

COOKS PEAK-FLUORITE RIDGE 

The Cooks Peak district in Luna County is about 30 

miles (50 km) northeast of Deming. The district is credited 

with a production of 58,011 tons of which about 56,780 

came from the White Eagle mine and the rest from four 

other deposits (Williams, 1966). 

The district is underlain by a variety of rocks, including 

Precambrian granite, upper Paleozoic limestone, and Ter-
60 GEOLOGY AND RESOURCES OF FLUORINE 

tiary volcanic rocks. These have all been cut by faults that 

strike northwest or north. 

The White Eagle fluorspar deposits, like others in the 

Cooks Peak district, are in minor irregular, branching, 

brecciated, and overlapping fault zones of generally northwesterly trend (Rothrock and others, 1946, p. 98-102). The 

ore bodies have a total length of 850 feet (260m) and have 

been mined through a vertical range of 175 feet (55 m). The 

veins are nearly all in Precambrian granite, but the 

western 100 feet (30m) of one is in Tertiary rhyolite, and 

the fluorspar mineralization is believed to be related to the 

volcanic rocks. The fluorspar consists of white to palegreen fluorite with quartz and jasperoid impurities. 

Fluorspar in the north part of the Cooks Peak district 

(which includes the Linda Vista deposit; Williams, 1966, 

p. 35) occurs as stringers, pods, and veins in slightly 

brecciated volcanic rocks. These fluorspar bodies are 

generally small, less than 5 feet (1.5 m) wide, but are 

numerous and sporadically distributed over a large area. 

The Fluorite Ridge area in Luna County is near the 

southern end of the Cooks Range, about 15 miles (25 km) 

south of the Cooks Peak district and about 10 miles ( 15 km) 

north of Deming. The mining claims cover an area of 

nearly 1 m2 (2.6 km2). Ten deposits are known in the 

district, which has yielded about 65,400 tons, lOpercentof 

the total of the State. 

The district is underlain by sedimentary rocks of Paleozoic and Tertiary ages, and monzonite porphyry that 

intrudes them. All these rocks were cut by faults, basalt 

dikes, and veins of fluorspar and quartz. The veins and 

dikes strike north to north-northeast. All but the deposits 

of the Tip Top and Hilltop Spar prospects are fissure 

veins, which are cavity fillings in limestone. The deposits 

have been most productive in broad breccia zones and at 

vein intersections. The veins contain coarse-grained palegreen fluorite and coarse- to fine-grained white, green, 

or red fluorite. Quartz and clay are the main gangue minerals. 

SIERRA CUCHILLO 

Fluorite has been found in many places in the northern 

20 miles (30 km) of the Sierra Cuchillo in Sierra County, 

the part of the range extending south from Monticello Box 

to a point about east of Winston. In most places the 

fluorite is present only in small amounts, but fluorspar 

prospects have been opened and shipments have been 

made from a few of them. 

Tactite deposits on Iron Mountain, Sierra County, have 

been known for many years and have been investigated as 

possible sources of iron, beryllium, tungsten, and fluorite · 

(Jahns, 1944). The only ore shipped from the deposits has . 

been fluorspar; less than 100 tons was shipped in the early 

1950's. On the west side of Iron Mountain tactite replaces 

Carboniferous limestone that dips eastward into the 

mountain. The rocks that are richest in valuable minerals 

are found only in certain beds and near silicic intrusive 

masses. Most of these beds are truncated at a shallow depth 

by a large mass of intrusive igneous rock. The total tonnage of valuable tactite therefore is much less than the 

extensive outcrops suggest. 

The tactite contains many silicate minerals including 

the beryllium mineral helvite, and much scheelite and 

magnetite. Fluorite in dispersed small grains makes up 

5-35 percent of parts of the silicated rock. In one area 

fluorspar forms irregular tabular layers several feet thick 

and a few tens of feet long that yielded the ore that was 

shipped. The fluorite constitutes at least 75 percent of 

these layers, as white translucent grains several inches 

across. 

Several small fluorite-bearing veins in Tertiary volcanic rock have been prospected a few miles north of State 

Highway 52 and near the center of the Sierra Cuchillo. 

The fluorspar is moderately coarse grained, brecciated, 

and mixed with quartz, country rock, and calcite. None of 

the veins has been an economic source of fluorspar. The 

veins, together with fluorite in dry-wash sediments in this 

part of the range, attest to widespread fluorite mineralization; deposits of economic size and grade may be present in 

sedimentary rocks below the volcanic rocks. 

The Victorio prospect is about 2 miles (3 km) east of 

Chise in the Sierra Cuchillo. It is a shallow shaft and 

several trenches opened in a vein that cuts limestone of 

Carboniferous age. The vein strikes N. 25° E. and is almost 

vertical. It consists of brown jasperoid, finely crystalline 

quartz, and fluorite and is 3-3.5 feet (about 1 m) thick. 

The largest known fluorspar deposit in the Sierra 

Cuchillo was discovered in 1969 by Ira Young, of Winston, 

N. Mex. It is about 1 mile (1.5 km) south of the Victorio 

prospect and 2 miles (3 km) east-southeast of Chise. 

Fluorite has replaced several beds in limestone and forms 

mantos that dip gently to the west. The strike length of the 

mineralized beds exceeds 1,000 feet (300m) and mineralized rock extends at least 500 feet (150m) downdip. At the 

surface the total minable thickness of fluorspar is at least 

20 feet (6 m), and some mantos are more than 5 feet ( 1.5 m) 

thick. The individual mantos are separated from one 

another by sufficient unmineralized limestone to require 

the mining of each manto separately. The mantos contain 

both coarsely crystalline white to pale-green fluorite and 

very fine grained friable white "sugar spar." Barite is 

uncommon. The most abundant impurity is unreplaced 

limestone. 

The Ira Young deposit and the Victorio prospect are 

near the south ends of two major north-trending faults 

that occur in Canada Rancho de los Chivos and Montoya 

Canyon (Alminas and others, 1972). Fluorite can be found 

in concentrates panned from gravel from most tributaries 
COLORADO-NEW MEXICO-WESTERN TEXAS-SOUTHEASTERN ARIZONA 61 

that drain into these valleys as well as from the two main 

valleys. The wide extent of the favorable limestone formation and of fluorite mineralization suggests that additional deposits may be found in the area. 

ZUNI MOUNTAINS 

The Zuni Mountains in Valencia County form a low 

ridge that extends about 50 miles (80 km) southeastward 

from the vicinity of Gallup. Fluorite was discovered in 

them in about 1908 and mining began in 1937. About 

224,000 tons of fluorspar has been shipped. 

The Zuni Mountains consist of a broad dome of Precambrian crystalline rocks and Permian sandstone and 

limestone flanked by Mesozoic sedimentary rocks 

(Goddard, 1966). The rocks of Precambrian and Permian 

ages are cut by many steep dip-slip faults that trend northwest. In most places such faults separate the Precambrian 

rocks from younger rocks. A persistent north-trending 

fault cuts the Precambrian rocks and offsets the northwesttrending faults. The northwest-trending faults are 

strongly silicified fracture zones that are stained red by 

fine-grained hematite. Fluorite is present in them in a few 

places. 

The fluorspar veins in the Zuni Mountains are found in 

three groups, one near each end of the area of Precambrian rocks and one in its interior. All veins are within 

1,000 feet (300m) of northwest-trending faults. The veins 

strike northeast or east and are mineralized to depths as 

much as 800 feet (240m) and through widths as great as 15 

feet (4.5 m). They contain coarse-grained green and finegrained purple fluorite; much of the ore is high-grade 

fluorspar containing 85-93 percent CaF2• Calcite, barite, 

and rare sphalerite, galena and chalcopyrite are accessory 

minerals. Three mines in the district have yielded 

important amounts of fluorspar. In addition to the mine 

worked to a depth of 800 feet (240 m) two were worked to 

depths of 350 and 600 feet (105 and 180 m), with no 

diminution of either size or grade in the veins. 

SIERRA CABALLOS 

Fluorspar deposits have been explored along a distance 

of about 20 miles (30 km) in the Sierra Caballos, Sierra 

County. The deposits are clustered into a northern group, 

near and north of Palomas Gap, and a southern group. 

The northern group has been most productive, providing 

about 25,000 tons of fluorspar; the Illinois and Independence or Blue Jacket mines yielded about 21,000 tons of 

this production (Williams, 1966). 

The northern Sierra Caballos group of deposits is in an 

area of Precambrian granite and Paleozoic sedimentary 

rocks. The rocks were much faulted on the west side of 

the range, and open fractures and breccia zones formed, 

in which fluorite was deposited. The veins near Palomas 

Gap strike northeast and those farther north strike northwest. The Illinois mine achieved its large production from 

three parallel veins, the Universal, the Oakland, and the 

White Star. They are mainly in Paleozoic sedimentary 

rocks (Johnston, 1928; Rothrock and others, 1946). The 

Oakland vein has been traced for 1,600 feet (500 m) and 

continues as a vein of quartz foranadditional600feet (180 

m). Fluorspar was mined along 350 feet (105m) of the vein, 

with an average width of 11 feet (3.3 m) and average CaF2 

content of 50 percent. Barite and calcite are gangue 

minerals. The other two veins are shorter, but the Universal vein has been mined through a distance of 400feet(120 

m) and a vertical range of 200 feet (60 m). The average 

width was 9 feet (2.7 m) and the average CaF2 content 

about 50 percent. The fine- to medium-grained white and 

pale-green fluorite is intergrown with calcite and quartz. 

The Independence or Bluejacket mine was opened on a 

breccia zone that strikes N. 15°-20° W., between granite 

and sandstone. Fluorspar was mined from an opencut 

about 100 feet (30m) long. The ore, like that in the Illinois 

mine, contains quartz and minor amounts of barite. 

Most fluorspar deposits in the southern group are on the 

west side of the Sierra Caballos and a few are on the east 

side. The total fluorspar production has been about 9,000 

tons, of which 5,800 tons came from the Alamo (Nakaye) 

mine and 2,500 tons from the Lyda-K mine (Williams, 

1966). 

The Alamo or Nakaye mine was opened in fluorspar 

veins that strike northeast and northwest and occupy 

fractures in limestones of the Magdalena Group 

(Rothrock and others, 1946). The veins, opened by shafts 

and adits, contain brecciated limestone cemented by palegreen fluorite and calcite, as well as fluoritic fissu~e 

fillings. The Lyda-K mine exploits a fault-controlled vein 

in granite of Precambrian age; the vein is at least 2,000 feet 

(600 m) long. Recurrent fault movement has brecciated the 

early quartz-fluorite mixture, which was then cemented 

with purple fluorite. Shafts in the vein exposed it to a 

depth of 260 feet (80 m). 

GRANTS 

According to Peters (1958, p. 669-670), small bedded replacement deposits of fluorite are closely associated with 

uranium deposits in Jurassic limestone near Grants, N. 

Mex. "In some of the bodies, fluorite and calcite are the 

dominant minerals, with fine-grained uran1n1te 

incorporated in the fluorite crystals. The fluoritic 

uranium bodies lie within the Todilto limestone and 

locally within limestone lenses in the overlying shales of 

the Summerville formation." They are mostly in the 

upper half of the Todilto, which is generally about 15-25 

feet (4.5-7.5 m) thick. According to Peters (1958, p. 

669-670): 

The fluorite bodies within the Todilto limestone are irregular in outline. Some of the bodies have no apparent structural control; others 
62 GEOLOGY AND RESOURCES OF FLUORINE 

exhibit a relation to the regional fold and fracture pattern. Some of the 

bodies have a tendency to follow the local joint pattern as mantos or as a 

linear series of tabular lenses. An association exists between broad gentle 

folds and some of the mineralized zones in that ore is most commonly 

found in crest or trough areas. A more direct association is noted in the 

occurrence of sharply broken and crumpled synclines within some of 

the orebodies. 

SOUTHEASTERN ARIZONA 

DUNCAN 

Several fluorspar deposits occur on both sides of the 

State boundary between Arizona and New Mexico about 

20 miles (30 km) northeast of Duncan, Ariz., in the foothills of the Mule Creek Mountains. There are two main 

groups of deposits: those in the vicinity of the Fourth of 

July mine, which is in Arizona in Daniels Camp, China 

Camp, and Goat Camp canyons, and those along Bitter 

Creek farther north, which are on the State line. The area 

around the Fourth of July mine is underlain by porphyritic and vesicular olivine basalt and fine-grained 

rhyolitic tuff intruded by dikes of rhyolite porphyry. The 

rocks are fractured and brecciated along northwesttrending zones. Fluorspar occurs as veins, pods, and 

stringers in brecciated zones. The fluorspar consists of 

coarsely crystalline green fluorite, dense milky quartz, and 

minor amounts of psilomelane. Quartz, chalcedonic 

quartz, and calcite stringers are common throughout 

fractured and brecciated basalt; fluorite, however, seems to 

be mainly along major northwest-trending fractures 

where it forms lenticular zones within quartz-rich veins 

(Trace, 194 7). Total production of fluorspar from mines in 

Daniels Camp, China Camp, and Goat Camp canyons has 

been less than 8,000 tons CaF2, most came from the Fourth 

of July mine prior to 1946. Mined fluorspar shoots 

averaged about 3 feet ( 1 m) wide and 50 feet ( 15 m) long; the 

largest was about 400 feet (120 m) long. The fluorspar 

averaged about 65 percent CaF 2 and 25-30 percent silica 

(Wilson, 1950). 

Fluorspar deposits near Bitter Creek are concentrated 

along or between the Steeple Rock and East Camp faults, 

which are parallel northwest-trending faults about 2 miles 

(3 km) apart and 14 miles (23 km) long (Gillerman, 1964, 

pl. I). The faults separate a horst of predominantly dacitic 

volcanics of Tertiary age from younger Tertiary predominantly andesitic volcanics on either side. Small 

bodies of rhyolite intrude the other rock types. One mine, 

the Mohawk, which is in New Mexico, produced about 

3,000 tons of fluorspar grading 65-70 percent CaF 2 prior to 

1945 (Gillerman, 1964, p. 195). Fluorspar was found in 

pods, shoots, stringers, and disseminations in highly 

silicified breccia zones. Mined ore had widths as much as 7 

feet (2.1 m), but average widths were less. Ore consisted of 

pale-green fluorite, quartz, pyrite, and blocks of highly 

silicified country rock. Much of the fluorite is massive and 

crystalline or columnar and occurs in layers with quartz; 

some is very fine grained and intimately intergrown with 

chalcedonic quartz. Many fluorspar prospects in the 

vicinity of the Mohawk mine were originally gold or silver 

mines. Part of the Bitter Creek fluorspar area is the Steeple 

Rock mining district, New Mexico, where fluorite is a 

common gangue mineral in the gold and silver deposits 

that occur along the Steeple Rock and East Camp faults 

(Gillerman, 1964, p. 186). 

OTHER DEPOSITS 

The Lones tar mine at the eastern base of the Whetstone 

Mountains, Cochise County, ranks as Arizona's most productive fluorspar mine. During 1946-51 the grade of 

produced fluorspar was 85 percent CaF2; silica content was 

0.02-2.7 percent (Wilson, 1950). Coarse-grained green 

fluorite and quartz occur as layers in a northwest-trending 

fissure vein in Precambrian schist. Ore shoots average 

about 2 feet (0.6 m) wide, 25 feet (8 m) long, and 30 feet (9 

m) high (Wilson, 1950). 

Several small fluorspar deposits are located in the foothills east of the Tonto Basin post office, Gila County. 

Fluorite, quartz, muscovite, and clay minerals occur in 

narrow lenses, about 3 feet (1 m) in width, along fault 

zones in granite and granite gneiss. A bulk sample taken 

by the U.S. Bureau of Mines contained 72 percent CaF2, 20 

percent silica, and trace amounts of gold, silver, barite, 

iron, and calcite (Cummings, 1946, p. 4). Tonto Mining 

and Milling Company was reported to be producing fluorspar from the area in 1972 (Guccione, 1972, p. 70). 

CENTRAL AND EASTERN UNITED STATES 

By A. V. HEYL and R. E. VAN ALSTINE 

Fluorine deposits in the Central and Eastern United 

States vary widely in composition, size, and geologic type. 

Fluorine-enriched igneous rocks are common and widespread, and they consist mainly of granites, granodiorites, 

pegmatites, nepheline syenites, and mafic alkalic igneous 

rocks. Marginal varieties, considered magmatic by some, 

are nelsonite dikes composed of ilmenite and fluorapatite 

in central Virginia, and magnetite deposits that contain 

fluorite and fluorapatite at and near Iron Mountain, Mo. 

High-temperature deposits enriched in fluorine occur 

in the Appalachian structural belt, in the Ozark dome of 

Missouri, and in the Llano uplift of Texas. They include 

four types: 

1. Veins, lodes, and associated greisens that contain fluorite and topaz. These have been mined mainly for 

tungsten, tin, silver, lead, and gold. One group of 

deposits in Connecticut has produced a small quantity of fluorite. 

2. Disseminations of fluorite and topaz, commonly 

associated with small veins and tactites. Scheelite, 

gold, and cassiterite are common associated minerals. 
CENTRAL AND EASTERN UNITED STATES 63 

3. Complex skarns among which are iron and zinc deposits in· the Precambrian of New Jersey, Pennsylvania, and southeastern and northern New York, 

that contain fluorite, fluorapatite, rare-earth fluocarbonates, and in places abundant chondrodite, norbergite, and humite. 

4. Fluorine-bearing tactites along granite and pegmatite 

contacts, and contact iron deposits next to Triassic 

diabase in Pennsylvania. Fluorite and topaz are the 

main fluorine-bearing minerals. Magnetite, scheelite, wolframite, molybdenite, helvite, chalcopyrite, 

garnet, and rare-earth and thorium minerals are 

associated with the fluorine minerals. One contact 

zone on Long Island, Maine, has yielded a small 

quantity of fluorite for apothecary shops. 

Most deposits are veins which were formed at intermediate temperature. A few fluorite-quartz veins in the 

Cheshire County-Westmoreland district of southwestern 

New Hampshire have produced fluorspar. Complex 

fluorite-galena-sphalerite-quartz veins in the Faber, Va., 

area have also been productive. Other intermediatetemperature veins are silver-lead-copper-zinc-fluorsparbarite veins of the Connecticut Valley in Connecticut and 

Massachusetts and near Phoenixville, Pa. Somewhat 

more complex veins occur on Deer Isle, Maine, and at 

Thomaston Dam, Litchfield, Conn. 

Most of the fluorspar deposits in the Central and Eastern parts of the United States are low-temperature veins, 

mantas, breccia bodies, stockworks, pipes, and disseminated deposits of several types of origin. 

The most abundant deposits and some of the largest 

known economic concentrations of fluorspar are lowtemperature vein and manto deposits in the Mississippi 

Valley and in the Appalachian Valley and Ridge province 

near related zinc deposits. Of these, the largest 

concentration of fluorspar in the Nation is in the IllinoisKentucky district which contains Mississippi Valley-type 

(low-temperature vein and manto) deposits. Other 

Mississippi Valley-type deposits that have produced or 

may contain important resources are in the Central 

Tennessee district, the Cumberland River vein area, the 

Central Kentucky district, and the Rossie-Lowville, N.Y., 

area. 

Appalachian Valley and Ridge province deposits are 

numerous and occur from Alabama to Pennsylvania (Van 

Alstine and Sweeney, 1968). Most of these deposits 

(Appalachian type) are irregularly shaped to blanketlike 

breccia bodies or are clusters of discontinuous veins, in 

both Cambrian and Ordovician carbonate rocks. A few 

deposits are fissure veins and disseminations in quartzite, 

shale, and carbonate rocks. By far the largest and potentially most important district in the Appalachian belt is 

the Sweetwater district in eastern Tennessee south of 

Knoxville. Farther east near the Tennessee-North 

Carolina State boundary are the adjoining Del Rio, Tenn., 

district and similar Hot Springs, N.C., district; the former 

produced barite and a small quantity of fluorspar from 

breccia bodies, disseminations, and fissure veins in 

quartzite and crystalline rocks. A small tonnage has been 

produced from barite-fluorite breccia bodies that constitute the Gilley deposit in northeastern Alabama. 

Disseminations of fluorite distributed widely in vugs 

and thin veinlets along with calcite, dolomite, barite, 

celestite, and sphalerite are found in central Pennsylvania, western New York along the south shore of Lake 

Ontario, northeastern Iowa, northwestern Ohio, and in 

the Serpent Mound cryptoexplosion structure in southeastern Ohio (Heyl, 1968). Such deposits may have been 

formed by simple warm connate brines or cold meteoric 

waters, or they may in places indicate undiscovered 

districts of the geologically more complex Mississippi 

Valley type or Appalachian type. 

Residual or placer deposits derived from underlying 

bedrock deposits are known in a few places. Residual 

gravel spar deposits have been mined in western Kentucky, 

central Kentucky, and central Tennessee, but are 

unknown in the Appalachian region. The Streeter topaz 

placer in the Llano uplift of central Texas was described 

by Paige (1911), although a bedrock source has not been 

found. 

Several of the districts and deposits in the Central and 

Eastern United States are described in more detail below, 

State by State, because of their resource potential or geologic interest. For each State, deposits with the greatest 

commercial potential are described first, followed by 

deposits of geologic interest, or of potential byproduct 

production of fluorite. Other possible fluorine sources 

such as apatite, rare-earth fluocarbonates, and fluosilicates are described last. 

ILLINOIS-KENTUCKY 

ILLINOIS-KENTUCKY FLUORSPAR DISTRICT 

By R. D. TRACE 

More than three-fourths of the fluorspar produced in the 

United States has come from the Illinois-Kentucky 

district. Substantial quantities of zinc and some lead and 

barite also have been produced, mostly as a byproduct of 

fluorspar mining. The district is in Hardin and Pope 

Counties in southeasternmost Illinois, and adjacent 

Crittenden, Livingston, and Caldwell Counties of western 

Kentucky (fig. 23). Nearly all the mines are within the 

boundaries of 16 7~-minute quadrangles aggregating 

nearly 1,000 mi2 (2,500 km2). The Illinois Geological 

Survey has published geologic maps of the Illinois part of 

the district, and the U.S. Geological Survey, in cooperation with the Kentucky Geological Survey, in 1972 has 

published geologic maps for most of the Kentucky quadrangles. 
64 GEOLOGY AND RESOURCES OF FLUORINE 

The earliest mining in the district was for lead at the 

Columbia mine, Crittenden County, Ky., in 1835 (Ulrich 

and Smith, 1905, p. liS). Lead mining started shortly 

thereafter in Illinois (Norwood, 1866, p. 366-372). From 

1835 to the early 1870's, little fluorspar was mined. Only 

small amounts were produced from the early 1870's to 

about 1890, when an expanded market was created by the 

development of the basic open-hearth steel furnace in 

37°30'00" 

37°22'30" 

37"15'00" 

which fluorspar was used for flux. Production since 1890 

has been erratic but in general has risen. Production 

during World Wars I and II and the Korean conflict rose 

sharply, but in 1953-58, because of rising imports, production in the district decreased. Production has risen in 

recent years and probably will continue to increase in the 

near future. Production figures are summarized in the 

following table. 

EXPLANATION 

Fault 

Mafic dike or sill 

o Intrusive breccia 

+ Structural arch 

<S::> Outline of area of known 

fluorspar deposits 

X 

X 

0 4 8 MILES 

~----~--~~------J 

0 4 8 KILOMETRES 

FIGURE 23.-Major structural features, igneous rocks, and distribution of known fluorspar deposits, Illinois-Kentucky fluorspar district. Compiled 

from published and unpublished geologic maps, 1962-72, by Illinois Geological Survey and U.S. Geological Survey. 
CENTRAL AND EASTERN UNITED STATES 65 

Fluorspar production from Illinois and Kentucky 

[From U.S. Bur. Mines Minerals Yearbooks unless otherwise noted] 

Years 

Illinois 

Through 1963 ...................................................................... . 

1964 ······················································································· 1965 ······················································································· 1966 ...................................................................................... . 

1967 ······················································································· 1968 ······················································································· 1969 ...................................................................................... . 1970 ...................................................................................... . 

1971 ······················································································· 

Total .......................................................................... . 

Ientucky 

Through 1963 ...................................................................... . 1964 ...................................................................................... . 

1965 ······················································································· 1966 ...................................................................................... . 

1967 ······················································································· 1968 ...................................................................................... . 1969 ....................................................................................... . 

1970 ······················································································· 

Total .......................................................................... . 

tU.S. Bur. Mines estimate. 2Estimate by R. D. Trace. 

Tons 

6,163,345 

127,454 

159,140 

176,175 

210,207 

188,325 

88,480 

148,208 

1141,000 

7,402,334 

3,016,980 

38,214 

31,992 

28,725 

32,952 

17,050 

210,000 

25,000 

3,180,913 

Until the early 1930's almost the entire production was 

from vein ores. Since then, the amount of ore produced 

from bedding-replacement deposits near Cave in Rock, 

Ill., increased and so by the middle to late 1960's beddingreplacement ore probably constituted more of the Illinois 

production than did vein ore. The rise in the beddingreplacement to vein-ore ratio was in part due to the 

depletion of some of the large vein deposits near Rosiclare. Within the last few years the Illinois production 

from veins has increased and may soon equal the 

production from bedding-replacement deposits. In 

Kentucky, nearly all production has been from veins, 

althoughasubstantialdepositofbedding-replacementore 

near Joy has been known since the 1950's and was put into 

production in 1970 and was mined until 1973. 

GEOLOGIC SETIING 

Sedimentary formations that crop out in the district 

range in age mostly from Late Devonian through Early 

Pennsylvanian; where mining has been concentrated, the 

rock units at the surface are the Meramecian and 

Chesterian Series of Mississippian age. A small amount of 

unconsolidated Cretaceous and Tertiary sand, silt, clay, 

and gravel and Quaternary loess and alluvium is present 

locally. 

The geologic column of exposed formations in the 

Illinois part of the district was summarized by Grogan and 

Bradbury ( 1968, fig. 2) (fig. 24). A slightly different column 

applicable only to the Kentucky part of the district is 

shown in figure 25. The lithologies in Illinois and 

Kentucky are generally similar but some differences in 

nomenclature are evident. 

Most of the vein ores occur where the wallrocks are of 

either early Chesterian or late Meramecian age (early 

Chesterian and late Valmeyeran in fig. 24). The three 

principal bedded ore horizons also are either in the lower 

part of the Chesterian Series or in the upper part of the 

Meramecian Series. 

Numerous intrusive mafic-alkalic dikes and a few sills 

are present in the district, and in addition in Illinois 

breccia forms dikelike or pluglike bodies (fig. 23). The 

mafic dikes and sills have been called mica-peridotites and 

lamprophyres; most are so highly altered as to defy precise 

classification. The dikes and sills are mostly dark gray to 

dark greenish gray, finely crystalline, and commonly porphyritic. They are composed mainly of dolomite, calcite, 

serpentine, chlorite, and generally phlogopitic biotite. 

Small quantities of magnetite, leucoxene, marcasite, 

fluorapatite, garnet, perovskite, and goethite are 

commonly present. Olivine and pyroxene are primary 

constituents but in a majority of the dikes these minerals 

mostly have been altered to serpentine (Clegg and Bradbury, 1956; Koenig, 1956; Trace, 1962b). Rarely, the mafic 

rocks are medium to coarsely crystalline (sample no. 197 in 

Zartman and other, 1967), light gray, and contain no 

chlorite or serpentine. Oesterling (1952, p. 324) described 

light-green dike material composed "nearly entirely of 

fine-grained calcite. The phlogopite has been completely 

replaced by calcite; there is no indication that olivine or 

pyroxene phenocrysts were ever present.'' 

Chemical and semiquantitative spectrographic 

analyses of samples of the Illinois dikes and sills were reproted by Bradbury (1962) and chemical analyses of samples of Kentucky rocks were given by Koenig (1956). The 

highly weathered Robinson dike near Hicks dome, 

Illinois, (Bradbury and others, 1955, p. 8) and similarly 

altered material from the Fowler dike in the east-central 

part of the Salem quadrangle, Kentucky (Trace, 1962a) 

were sampled in 1955. Semiquantitative spectrographic 

analyses of the samples showed that the Robinson dike 

contains much larger quantities of rare earths than does 

the Fowler dike (see fig. 23), as shown in the following 

table. 

Semiquantitative spectrographic analyses of weathered mafic dikes, 

Illinois and Kentucky 

[Analyses by Mona Frank, U.S. Geol. Survey, Sept. 1955] 

Percent Robinson dike 

(Near Hicks dome, Illinois) 

>10 ........................ Si 

5-10 ..................... Fe AI 

1-5 ...................... Ti Mg 

0.5-1 ...................... Ca K Na 

0.1-0.5 .................... Ni Y Ba Ce 

0.05-0.1 .................. Mn Nd 

0.01-0.05 ................ La Sr V Co Cr Zr Cu 

0.005-0.01 .............. Nh Zn Ga 

0.001-0.005 ............ Yh Ph Mo Sc Be 

0.0005-0.001.. .............. . 0.0001-0.0005 ......... Ag 

Fowler dike 

(East-central part of Salem 

quadrangle, Kentucky) 

Si 

FeAl 

MgCa 

TiK 

Ni Cr 

Mn Ba Na Sr V Cu 

CoGa 

La Nh Y Ph Nd Zr Mo Sc 

Yh Ag Be 
66 

2 en 

"' "' .... 

en ~ 

> 

en en "'

FORMATION MEMBER 

GEOLOGY AND RESOURCES OF FLUORINE 

LITHOLOGY 

·: ...... ·:.~ •. :.+ 

THICK· 

NESS 

(FT) 

LITHOLOGIC DESCRIPTION 

..:.z 

><( Cl)_ 

zz 

Z<( 

1!:J ri-....,..-:-K-:-:1-:-:N~K~A~ID=----------15:r-:+l·£! :~:I ::ds~::~~ ~~::~::· .. :::Is 

DEGONIA ~ 0 - 30 Shale and thin· bedded sandstone 

z 

<I 

~ 

z 

'<I z-

<I~ 

z- -~ 

0(/) 

>~ LUCI) 

0~ 

2 

--z 

Cl 

-

z 

0 

> 

LU 

0 

CLORE · · · · · ··100-120 St'tale; limestone; thin- bedded sandstone 

: 50-60 Sandstone· silty shale PALESTINE 

MENARD 

z r.W7.7A-:-'L;T;E,;::R~S=-=e;:';'u-:;R"G;;-----~\ 100-130 Fine- grained limestone; shale 

e1: VIENNA -=··~:· ... 15-50 Shale· shaly sandstone u- <!l 1 L tmeSTQ_n_e· __Sl1QJ_V_ 1mes1 ne ~ TAR SPRINGS :· .. :::·.>:=":-.;::90-110 Sandstone; shale;thin coal 

"' GLEN DEAN ~ ·.· · .... 40- 70 Fossiliferous partly oolitic limestone; shale .,_ HARDINSBURG en HANEY \ · ~' ... '77':.~: 90-115 Sandstone; shale ~·: ... ,·::·~:-;:;. 1 Fosstliterous ume~one 

"' FRAILEYS t l: BEECH CREEK \ ~ _ _ 105-14C I Shale· thtn ltmes one u Stlty limestone CYPRESS 

1\ 

,.....,_ 

RIDENHOWER <~.~:.~:<J.: 80-110 Sandstone; shale 

r.B::-:E~T=H:7.:E L:=..=..:...;..:..._ ____ ,"~;:#,~ 25-65 Shale· shalv sandstone 

...:D::-:O~W:...:N.:..::E~Y~S:--::8:-L-:-U:-::F:-::F:---,\. . ::: .o:ISQ.-100 Sandstone 

li:::i::S.:·:·. ~~-«tO Crinoidal locally oolitic limestone 

YANKEETOWN 30-45 Shalei siltstone (Yankeetown); limestone· shale (Shetlervillt)_ She11erville 

Levi as RENAULT 15-35 Liaht-colored oolihc limestone (Levias) 

AUX VASES Rosiclare 15 -35 Calcareous sandstone shale at base 

STE.GENEVIEVE S.~»ar Mtn. J 12o-t60 LtghT- colored larCJely ooliTic limestone; sandstone lenses 

350- 400 Fine- CJrained cherty 1 imestone 

500! Dark-colored, fine -grained limestone; foraminiferal calcarenite 

~~~ Crinoidal, bryozoan limestonei dark·groy fine·CJrGined limestone 

FORT PAYNE 

SPRINGVILLE 

= J _: ;_:,_:-

Gray and _greenish-ara_y shale 

NEW ALBANY GROUP 395! Gray to black shale 

LINGLE 

GRAND TOWER 250: Limestone and chert 

CLEAR CREEK . _l_ • • 

RANGE OF 

FLUORITE 

DEPOSITS 

VEINS BEDDED 

-.... 

-

FIGURE 24.-Stratigraphic column of exposed formations in the Illinois-Kentucky fluorspar district. From Grogan and Bradbury (1968, fig. 2). 
CENTRAL AND EASTERN UNITED STATES 67 

SERlE~ FORMATION 

THICKNESS, SYSTEM AND LITHOLOGY DESCRIPTION 

MEMBER IN FEET 

z: ~:_:_:-;::;: ;;~ <C 

z 

> 

<C ~ II __, 60-765 Sandstone; shale; thin coals >-

en 

z: 

z: 

UJ 

~ 

Kinkaid Limestone 

~~ ~:.:··!T.:, 0-165 Limestone, sandstone, and shale 

Degonia Sandstone ........ / 5-38 Shale and sandstone 

Clore Limestone e ·-==--~-=-_:.-..:..: 70-125 Shale and limestone; thin sandstone 

Palestine Sandstone ~:~::;::::·.·.:-: 30-75 Sandstone and shale 

Menard Limestone ~ .... ;--= 80-145 Limestone and shale; thin sandstone locally 

Waltersburg Sandstone 20-60 Shale, siltstone, and sandstone 

Vienna Limestone " :~ 

15-35 Limestone, cherty 

c: ~. - Tar Springs Sandstone 11:1 ~;::;::.::.::-::·~·.~ 70-120 Sandstone and shale; thin coal locally ·;::: 

cu Glen Dean Limestone 40-95 Limestone and shale 't) 

cu 

.c: Hardinsburg Sandstone ............... c.:> 80-150 Sandstone and shale 

:-::. ·.: ::-::.:/::-: 

Golconda Formation ----"'"": 90-165 Shale ar,~d limestone; thin sandstone common 

~ = 

Cypress Sandstone ::~::~---~ 45-140· Sandstone and shale; thin coal locally :.·. ·• ·. · ... ·• ·• ·.-: .. Paint Creek Formation ~---~ 5-100 Shale, limestone, and sandstone 

Bethel Sandstone -: :::·::·~=.::!===·=}~;:f.:~~ 20-120 Sandstone 

Renault Limestone 70-125 Limestone and shale 

................ 

. 0 0 0 0 0 

z: Ste. Genevieve <C 200-300 Limestone, oolitic; thin sandstone 0 0 0 0 oo 

0::: Limestone 0 0 0 0 

~ 0 0 0 .. 0 v; 

en .. 0 .. ... 0 0 v; 

en 

:E Upper 0 0 0 

250+ member Limestone, cherty, partly oolitic 

c: .. 11:1 St. Louis . 500- "(3 

cu Limestone 530 E 

f! Lower 250- Limestone, cherty; containing Lithostrotion colonies cu 

:::E member 280 

. . . 0 .. Salem Limestone 120+ Limestone, oolitic at top 

Warsaw Limestone 230+ Limestone, large Echinocrinus spines at top 

~ 

0 

I 

. c: Olololi 11:1 Fort ol ol o Limestone, mostly dark gray and very cherty or silty; cu 

bD Payne bl •I •I o 600± 11:1 locally upper part is light gray Cl) Formation •I •1•1• 0 ~lol • I • lo 

•I • I • I o I • ~olol•l•l 

•I o I• I o I o F>1 o I o I o J .. 1~ 

ol• I • I o I• 

DEVONIAN Chattanooga Shale ----=----=-=-~ Dark-gray shale 

FIGURE 25.-Generalized stratigraphic column of exposed formations in the western Kentucky fluorspar district. 
68 GEOLOGY AND RESOURCES OF FLUORINE 

In the last two decades, many more dikes and sills have 

been found principally because of the large amount of 

diamond drill exploration. A few new occurrences also 

have been found from surface mapping (Amos, 1966; 

Trace, 1966); mafic rock is difficult to find in surface 

outcrop, however, because a freshly exposed outcrop 

decomposes within a few years and becomes difficult to 

recognize. Also, the mafic rock material appears fresh and 

superficially resembles dark-gray limestones where 

exposures are continuously washed clean such as on Claylick Creek near the eastern edge of the Salem quadrangle 

(Trace, 1962a). 

Numerous breccias and breccia "dikes" have been 

mapped in the Illinois part of the district (Baxter and Desborough, 1965; Baxter and others, 1967) and have been 

described in some detail (Clegg and Bradbury, 1956; 

Brown and others, 1954). According to Baxter and Desborough (1965, p. 287), "The breccias consist of angular to 

subrounded fragments of sedimentary, metamorphosed 

sedimentary, and igneous rocks in a matrix of finely 

ground rock and mineral fragments. The mineral fragments include quartz, pyroxene, augite, hornblende, 

apatite, mica, and feldspar." Grogan and Bradbury (1968, 

p. 376) identified fine-grained nepheline-feldspar rock in 

one of the breccias. 

Many of these breccias are inferred to be pipes or small 

stocks, roughly circular or elliptical in plan and as much 

as 1,000 feet (300 m) in diameter. More commonly the 

breccias are vertical or steeply dipping dikelike bodies. 

Unusual mineralization occurred in many of the 

breccias, both on the surface and to depths of over 2,000 

feet (600 m) (Brown and others, 1954, p. 897-900; Heyl and 

others, 1965, p. Bll; Bradbury, 1962, p. 6-8; Trace, 1960; 

Hall and Heyl, 1968). Minerals present are rare-earthbearing fluorite, sphalerite, galena, barite, monazite, 

bertrandite, florencite, calcite, quartz, pyrite, brookite, 

yttroparisite(?), biotite, rutile, xenotime, apatite; 

beryllium, niobium, and zirconium are present in more 

than normal concentrations. 

Until the early 1960's, the dikes, sills and breccias could 

be dated from stratigraphic relations only as post-Middle 

Pennsylvanian. In 1967 Zartman and others (p. 860-861) 

studied samples of biotite and hornblende from the dikes, 

sills, and breccias; on the basis of radio-isotope data they 

reported that "All the ages lie within experimental uncertainty of each other and give an average Early Permian age 

of 267 million years.'' 

Wallrock alteration associated with vein deposits 

occurred along faults. Silicification of wallrock was the 

most striking change. Where Chesterian sandstone 

comprises the wallrock, sandstone close to or within the 

fault zone is extremely dense and commonly makes outcrops which are called "quartz reefs" or quartzite. Indeed, 

fragments of quartzite in places provide the only evidence 

of the surface trace of faults. 

The alteration of limestone wallrocks generally was 

slight to moderate. In places numerous small doubly 

terminated quartz crystals and small masses of chalcedony 

have been reported where limestone is adjacent to a vein 

(Hardin, 1955, p. 24; Trace, 1962b, p. 17; Trace, 1954, p. 

70). Fragments of dolomitic limestone, which is relatively 

common in the country rocks of the area, are present 

within the veins. No secondary dolomitization of the wallrocks of vein deposits has been reported. 

Hall and Hey] (1968. p. 661) described visible wallrock 

alteration as much as 100 feet (30 m) laterally from 

bedding-replacement deposits. According to them, alteration included solution thinning of strata, silicification, 

dolomitization, and clay mineral alteration. Brecke ( 1962, 

p. 525-530) described the alteration of country rock, 

mostly within the mineralized zones, as decalcification, 

dolomitization, and silicification. 

According to Heyl and Brock (1961, p. D3), 

The Illinois-Kentucky mining district is centered in the most complexly 

faulted area in the central craton of the United States. Structural studies 

suggest that the mining district lies within a collapsed, block-faulted, 

sliced, and partly rotated domal anticline that is located at and near the 

intersections of several major fault lineaments. 

(See fig. 26.) Prominent fault zones that intersect at the district are the east-trending Cottage Grove-Rough CreekShawneetown system-coinciding with Heyl's (1972) 

38th-Parallel lineament -and the northeast-trending New 

Madrid fault zone. 

Within the fluorspar district (fig. 23) the rocks are 

complexly broken by a series of steeply dipping to vertical 

normal or gravity faults that trend dominantly northeast 

and divide the area into a series of elongated northeasttrending blocks. Many cross-faults that trend north to 

northwest are occupied in places by mafic dikes. Near the 

east edge of the Kentucky part of the district, the faults 

trend more nearly east; and radial and arcuate faults are 

present around Hicks dome. 

Hicks dome is a structural high with about 4,000 feet 

(1,200 m) of vertical uplift that is centered in the southwest part of the Karbers Ridge quadrangle (Baxter and 

Desborough, 1965). Brown, Emery, and Meyer (1954) 

described the dome as an incipient cryptovolcanic structure, on the basis of breccias (in an oil testholeandnearby 

at the surface), arcuate faults, and unusual mineralization. As a result of an aeromagnetic survey, McGinnis 

and Bradbury (1964, p. II) stated that: "Hicks Dome is not 

underlain by a laccolithic intrusion. • • • A broad 

magnetic anomaly of relatively low intensity centered 

about 5% miles [9 km] northeast of Hicks Dome and the 

featureless configuration of contour lines around the 

anomaly suggest a large igneous body overlain by a thick 

sedimentary rock section." 

The southeasterly extension of Hicks dome is partly 

obscured by a fault zone 4-5 miles (6.5...;8 km) wide known 

as the Rock Creek graben (fig. 23). Southeast of the graben, 

the structural high reappears as the Tolu dome or arch, 
OZARK 

I ··1-

DOME ' 

--~£R_!_ __ ARKANSAS 

CENTRAL AND EASTERN UNITED STATES 

0 

I 

0 

25 

I 

I I 25 50 

... · 

.··•· 

l 

: 

KENTUCKY ••••••• : 

---TENNR~~--

/ FLYNN CREEK WELLS CREEK / DISTURBANCE 

$DISTURBANCE ·" $ 

NASHVILLE / DOME 

50 75· 100 MILES 

1

1 I I I 

75 100 KILOMETRES 

EXPLANATION 

Bue ~ of Cretaceous rocks 

I I 

MiaiiiSippian \hrouch Cambrian rocka 

1--L-- Fault 

Sllowi'llfl dip arod dinetioft of 

dupu.n-t wlun kftnm; 

~ 

dashed wlun i'lfwr.d or 

$ 

lnteuely disturbed 

localized uplift 

-+- Anticline 

Area I of lltinois-Kentacky 

diNiet 

69 

FIGURE 26.-Major structural features in the region surrounding the Illinois-Kentucky fluorspar district. Modified from Heyl and Brock (1961, 

fig. 294.1 ). 

which is centered about a mile east of Tolu, Ky., in the m); more commonly it is a few hundred feet. Total disCave in Rock quadrangle (Baxter and others, 1963). placement across the fault zone is commonly distributed 

Southeast of the Tolu dome is another series of grabens irregularly among the several individual faults-in places 

(Weller and Sutton, 1951) bounded on the south by the as step faults and also small grabens within the fault zone, 

Tabb fault system (Rogers and Hays, 1967); in this area a such that all faults either are vertical or dip toward the 

structural high is difficult to trace because of numerous hanging wall of the fault zone. In some places, small 

faults. Possibly an extension of the high is shown on the grabens are formed by antithetic faults that dip toward 

Salem quadrangle (Trace, l962a) between the Levias- the footwall side of the fault zone (fig. 27). Minor antiCrittenden Springs fault system and the Moore Hill fault thetic faults and fractures are present in places for a few 

system. Farther south in the Dycusburg quadrangle, pre- hundred feet from the margins of the major graben. 

liminary mapping suggests three more possible segments Vertical displacement generally has been considered to 

ofthearch (Dewey Amos,oralcommun., l97l)(seefig. 23). have been the principal direction of movement along the 

Nearly all the faults of the district are normal and dip major northeast-trending faults in the district. Clark and 

generally 75° to vertical; rarely are they inclined as low as Royds (1948) and Heyl and Brock (1961), however, 

45°. Locally the dip of a fault or vein is reversed. Along the suggested that a horizontal component of movement may 

edges of many of the larger grabens, fault zones consist of have been significant. Field mapping has shown that as 

several subparallel and sinuously intersecting faults. The much as 3,000 feet (900 m) of vertical displacement may 

total width of these zones may be more than 1,000 feet (300 have taken place, but movement generally has been much 
70 GEOLOGY AND RESOURCES OF FLUORINE 

SE NW 

C Overburden = c 

0 

0 25 50 75 METRES 

EXPLANATION 

Fault breccia Fluorspar 

-

FIGURE 27.-Cross section of Davenport mine, Moore Hill area, Kentucky. Cc, Cypress Sandstone; Cpc, Paint Creek Formation; Cb, Bethel 

Sandstone; Cr, Renault Limestone; Cl, Levias Limestone Member of Ste. Genevieve Limestone; Crc, Rosiclare Sandstone Member of 

Ste. Genevieve Limestone; Cf, Fredonia Limestone Member of Ste. Genevieve Limestone; Csl, St. Louis Limestone. Modified from Thurston 

and Hardin (1954, pl. 14). 

less. Evidence of strike-slip movement on the faults is 

conflicting; there is no evident horizontal offset of the 

northwest-trending mafic dike swarm where these 

elements are cut by northeast-trending faults, but there is 

some possible horizontal offset of the northwest-trending 

structural high (fig. 23) along these faults. Data from a few 

drill holes in the Crittenden Springs and Commodore 

areas (Salem quadrangle) suggest that the amount of 

vertical displacement on faults at depths of nearly 2,000 

feet ( 600 m) below the surface is substantially the same as at 

the surface. 

At least some and probably most of the major northeasttrending faults are younger than Hicks dome and the 

mafic dikes, and therefore are post-Early Permian in age. 

The major displacement along these faults may have been 

completed by middle Cretaceous, although some movement has continued through Cretaceous and Tertiary time 

and up to the present (Rhoades and Mistler, 1941; Ross, 

1963; McGinnis, 1963; Amos, 1967). Some faulting may 

have begun as early as Early Pennsylvanian time. 

FLUORSPAR ORE DEPOSITS 

Most of the fluorspar ore deposits are along northeasttrending faults; a few veins are found along the northwest-
CENTRAL AND EASTERN UNITED STATES 71 

and north-trending faults and in places are associated with 

mafic dikes (Trace, 1962b). The distribution of known 

deposits is shown on figure 23. D. R. Shawe observed 

(written commun., 1972) that the ore deposits tend to be 

concentrated in areas of mafic dikes and breccia pipes, as is 

suggested from figure 23; Trace is doubtful of the spatial 

association, however. 

Fluorspar ore bodies occur dominantly either as steeply 

dipping to vertical vein deposits along faults or as lowdipping to nearly flat bedding-replacement deposits along 

certain stratigraphic horizons in Mississippian limestones (fig. 24; Currier and Wagner, 1944). A few deposits 

are a combination of vein and bedding-replacement type 

ores and so-called gravel deposits that resulted from a 

fluorite concentration in the residuum overlying vein 

deposits. Protore amounts of disseminated fluorite are 

present in the breccias of Hicks dome (Brown and others, 

1954). 

The fluorspar veins commonly are fissure fillings along 

faults and in fault breccias, accompanied by replacement 

of vein calcite and some wallrock. A typical vein is 

lenticular, pinching and swelling erratically, and is 

commonly a mixture of fluorite and highly variable 

quantities of calcite and country rock fragments. Locally 

the entire vein may be either calcite or fluorite. Commonly 

the vein walls are sharp but in places veinlets of fluorite 

and calcite extend into the slightly broken wallrocks for a 

few hundred feet. 

The fluorite varies from commonly purple, fine- and 

medium-grained crystalline in small veinlets to 

commonly brown, white, or colorless, coarsely crystalline 

in more massive veins. In many places, the veins are 

complexly brecciated and (or) sheeted. Rude layering 

("banding") parallel to vein walls is present locally. Shaly 

fault gouge, presumably dragged in along the fault from 

the more shaly of the Chesterian units, is common in 

places. 

Most fissure-vein deposits average 3-10 feet (l-3 m) in 

width (Hardin and Trace, 1959; Trace, 1962b); a width of 

as much as 45 feet (14 m) is known. Mined ore shoots 

commonly range in strike length from 200 to 400 feet 

(60-120 m) though greater lengths are common in many 

places, particularly in the Rosiclare area. The average 

height of the ore shoots is 100-200 feet (30-60 m) but some 

ore shoots extend from the surface to a depth of nearly 800 

feet (250 m) (Grogan and Bradbury, 1968, fig. 10). 

The stratiform or bedding-replacement deposits are 

elongate bodies that trend northeast and less commonly 

southeast (fig. 28), and "are localized along a network of 

fractures and minor faults parallel to and half a mile distant from the Peters CreekJault • • •" (Grogan and Bradbury, 1967, p. 41-42). In cross section, they appear as flat 

wedge-shaped or crescentic (concave upward) forms with 

thicker parts adjacent to individual faults: A few nearby 

pipe like breccia zones are mineralized and may have been 

EXPLANATION 

- Bethel horizon 

8 Rosiclare horizon 

[::·.\:::}:·:1 Sub-Rosiclare bed 

e Breccia pipe 

0 

Peripheral T 

deposit · 

s. I 

11 

Peripheral deposit 

North 

Green 

)36 

(j/ 

R.9 E. 

0 2000 4000 FEET 

I I I I 

0 1000 METRES 

FIGURE 28.-Cave in Rock fluorspar district, Hardin County, Ill., 

showing elongate character of northeast-trending ore bodies. 

Modified from Brecke (1967, fig. 2. p. 381). 

conduits for ore solutions (Brecke, 1962, p. 5ll-514; 

Grogan and Bradbury, 1968, p. 393-394). 

The bedding-replacement ore bodies in Illinois are 

commonly 50-200 feet (15-60 m) wide,and5-20feet(l.5-6 

m) thick; their length is highly variable, from 200 feet (60 

m) to 2 miles (3 km). The grade of the ore also is highly 

variable, but the general grade of mine-run ore ranges 

from 20 to 35 percent of CaF 2 • 

The bedding-replacement deposit being mined in 

Kentucky is believed to be approximately 2 miles (3 km) 

long, 150-250 feet ( 45-75 m) wide, and averages 7 feet (2.1 

m) in thickness, containing about 30 percent of CaF~, and 

small quantities of zinc and barite (John S. Tibbs, oral 

commun., 1971). 

Texture of the bedding-replacement deposits was 

described by Brecke (1962, p. 515-525) as "banded," 

imperfectly "banded," and brecciated. The latter two types 

characterize the majority of the deposits. 

The deepest minable fluorspar in the Illinois-Kentucky 

district is in a vein in the Rosiclare area and at a depth of 

about 800 feet (235 m) (Grogan and Bradbury, 1968, p. 

380). In the Kentucky part of the district the deepest mine 

working on a vein is about 700 feet (210m). A substantial 

number of holes has been drilled in the Rosiclare area 

(Muir, 1947) to intersect the veins more than l,300feet(400 

m) below the surface, but at that depth they are 
72 GEOLOGY AND RESOURCES OF FLUORINE 

dominantly calcite and wallrock breccia. In Kentucky a 

few holes have been drilled to almost 2,000 feet (600 m) 

below the surface, with virtually the same results. 

The average grade of ore mined from the deposits has 

varied. Twenty to thirty years ago, the ore mined 

commonly contained at least 45 percent of CaF 2, but 

gradually the ore cutoff grade has dropped, probably to 

somewhere between 25 and 40 percent of CaF2 in 1972. 

Various factors have influenced the ore grade in addition 

to the selling price of the finished product, such as the 

amount of byproduct zinc and lead, and the varying costs 

of mining that depend primarily on the type of deposit and 

also on mine depth, amount of water, and degree of 

stability of mine walls or roof. 

The most abundant minerals in the vein deposits are 

calcite and fluorite. Concentrations of sphalerite or barite 

are present in places, although more commonly 

sphalerite, barite, and galena occur in small quantities 

with the fluorite. Minor quantities of quartz, pyrite, 

marcasite, and chalcopyrite are present and locally zinc, 

lead, or copper alteration products (cerussite, 

pyromorphite, smithsonite, hemimorphite, greenockite, 

cuprite and malachite). Celestite has been reported in one 

locality in Kentucky (Hardin and Thurston, 1945). 

The bedding-replacement deposits contain virtually the 

same suite of minerals. The principal difference is the 

quantity of calcite-abundant in the vein deposits, and 

common, though not abundant, in the beddingreplacement deposits. Fluorite is the principal mineral in 

the bedding-replacement deposits. Locally sphalerite, 

galena, and barite are abundant but generally they are 

uncommon. Calcite and quartz are widespread but sparse. 

Chalcopyrite, marcasite, pyrite, witherite, strontianite, 

smithsonite, cerussite, malachite, and pyromorphite have 

been reported. 

Paragenesis of the vein and of the bedding-replacement 

deposits appears to be similar. Of the more abundant 

minerals, calcite is the earliest, overlapped and followed 

by fluorite. Sphalerite and galena generally appear to 

overlap and follow fluorite, and barite is the youngest 

common mineral. Hall and Friedman (1963, p. 891) 

reported on the paragenesis of the Cave in Rock deposits, 

and Pinckney and Rye (1972) reported on oxygen and 

carbon isotope variations in minerals deposited at 

different times in the wallrocks. 

Fluid-inclusion studies of the temperature of deposition 

of the fluorspar have been done by Freas (1961) and 

Grogan and Shrode (1952). Their studies indicate a range 

in temperature from 90° to 140°C. 

The composition of fluid inclusions in the ore and 

gangue minerals of the Cave in Rock area was studied by 

Hall and Friedman ( 1963). According to them, the general 

composition of the fluid inclusions suggests that the 

fluorite was deposited from a concentrated Na-Ca-Cl 

brine, probably of connate origin. Fluid inclusions in the 

quartz, however, have lower salt content, have a high ratio 

of KINa, Ca/Na, Cl!Na, and S04/Na, and a lower relative 

deuterium concentration than that found in the fluorite 

itself. These fluids may represent a magmatic water. 

No apparent districtwide zoning of fluorite, sphalerite, 

and galena has been reported. Brecke (1964a) suggested 

that barite is more common on the fringes of the district, 

but exceptions in the Lola, Ky., area tend to obscure a 

broad picture of this zoning. Heyl (1969) suggested a 

zonation pattern for silver and antimony in galena, 

around Hicks Dome (see also Heyl and others, 1966), and a 

systematic change in the lead isotopic ratios from Hicks 

dome southeast into Kentucky. 

Close dating of the age of mineral deposition has been 

difficult. Heyl and Brock (1961, p. D6) reported an age of 

90-100 m.y. (middle Cretaceous) for monazite in fluoritebearing breccia found at Hicks Dome, but this age is in 

doubt because of the weathered character of the monazite 

(Heyl, written commun., 1972). No other direct evidence 

exists for the age of the deposits. 

Minor elements in the ore deposits have been reported 

by Hall and Hey 1 ( 1968). According to them, the fluorite is 

remarkably pure, except for the fluorite in breccias at 

Hicks dome which contains abundant rare earths. The 

sphalerite of the district is relatively high in cadmium, 

germanium, and gallium, but low in silver. The galena 

contains varying quantities of silver. 

SUMMARY 

The geologic history and genesis of the IllinoisKentucky fluorspar district have been discussed by 

Amstutz and Park (1967), Brecke (1962, 1964b, 1967), 

Brown (1970), Grogan and Bradbury (1968), Hall and 

Friedman (1963), HallandHeyl (1968), Heyl, Brock, Jolly, 

and Wells (1965), Heyl (1969), Oesterling (1952), Park and 

Amstutz (1968), and Snyder and Gerdemann (1965). The 

origin and chronological age of many of the significant 

geologic features of the district are still not established. 

Many structural and mineralogical events must have both 

overlapped and recurred, and therefore many a geologist 

has been confused and frustrated in attempting to 

establish the correct geologic history. In general, however, 

the history can be divided into three broad phases, all of 

which occurred principally within the interval of postMiddle Pennsylvanian to Cretaceous. The oldest events 

were the structural arching and formation of Hicks and 

Tolu domes, the intrusion of dikes and sills, and the 

formation of breccias. From the data of Zartman, Brock, 

Heyl, and Thomas (1967) these features appear to be early 

Permian in age. Next came most of the movement along 

the northeast-trending faults, followed by the third major 

phase, that of mineral deposition. 

The general location of the Illinois-Kentucky district 

may be structurally controlled by the intersection of the 

northeast-trending faults of the New Madrid system with 

mafic dikes, and the structural high trending northwesterly through the district, and possibly with an east-
CENTRAL AND EASTERN UNITED STATE~ 73 

trending lineament of igneous activity described by Snyder 

and Gerdemann (1965) that is part of Heyl's (1972) 38thParallel lineament. In the district, the primary localizing 

elements, particularly for the vein deposits, were faults, 

which served both as ore solution channelways and as 

space for the ore bodies. Fractures and minor faults 

apparently were aslo a significant factor in the localization of the bedding-replacement deposits although the 

control exerted by these structures on the shape of the 

replacement deposits is somewhat less obvious than their 

control of shape of the vein deposits. In addition, relatively 

impermeable blanketing lithologic units, breccia pipes, 

and unconformities have been suggested as contributing 

to the localization of the bedding-replacement deposits. 

These factors were discussed by Brecke (1962) and by 

Grogan and Bradbury (1968). 

The veins contain highly variable quantities of calcite 

and fluorite, and so far as the writer is aware, no guides are 

known to predict the calcite/fluorite ratio of a given vein, 

and thus to indicate the favorableness of the vein. 

Vein widths appear to be directly related to the 

lithology of the fault walls (Grogan and Bradbury, 1968; 

Thurston and Hardin, 1954; Hardin, 1955; and Trace, 

1962b, 1954). Most of the ore has been mined from veins 

where one wall and commonly both walls are made up of 

the Mississippian rocks from the St. Louis Limestone up 

through the Cypress Sandstone totaling about 1,000 feet 

(300 m) in stratigraphic thickness. Possibly this control 

was effective because these units are dominantly 

competent and massive in contrast to the post-Cypress 

units that contain many beds of incompetent shale, siltstone, and thin-bedded sandstone. Openings formed by 

faults where the walls are Cypress or older likely remained 

open for vein fillings, and incompetent shaly material was 

not as likely dragged into the fault zones. Also, in the more 

competent beds, the faults may steepen in dip, which 

could have allowed more space for mineral deposition. 

Similarly, where competent beds were faulted, the total 

displacement of the fault system was taken up by many 

faults (thus creating more space) rather than by a few faults 

with steeper drag-folded walls, such as where post-Cypress 

units were faulted. 

Moderate fault displacement appears to have favored 

vein formation (Thurston and Hardin, 1954, p. 98); 

Grogan and Bradbury ( 1968, p. 390-392) suggested 25-500 

feet (7 .5-150 m) as the optimum displacement along faults 

occupied by veins. 

A change in overall strike of a fault system may have 

influenced vein width in places. Possible examples are the 

Babb (Trace, 1962a) and Dyers Hill (Amos, 196'l)areas in 

Kentucky and the Rosiclare area (Baxter and Des borough, 

1965; Amos, 1966) in Illinois. 

Several writers have noted the spatial association locally 

of vein deposits that are principally zinc-bearing (and also 

of fluorspar deposits that contain substantial byproduct 

zinc and lead) either along northwest-trending mafic dikes 

(Hutson and Old Jim mines) or where dikes intersect 

northeast-trending faults (Hickory Cane mine). Recently a 

new deposit containing abundant sphalerite was found in 

Livingston County, Ky., near a mafic dike (The Mining 

Record, Denver, Colo., Dec. 23, 1970). On the other hand, 

the Nine Acres mine, Kentucky, contains principally 

sphalerite, but no mafic rocks are known in the immediate 

vicinity. As the dikes probably were intruded prior to 

mineral deposition, the genetic relationship between them 

and the mineralization is obscure. 

Brecke (1967, p. 387) suggested that zinc sulfide 

deposition may have been related to iron sulfide present in 

the mafic rocks. Oesterling ( 1952, p. 332) suggested that 

sphalerite was deposited where post-fluorite faulting took 

place along the dikes. Hardin ( 1955, p. 23) stated that the 

distribution of sphalerite was controlled to some extent by 

the cross-faults and subparallel faults of the fault zone; 

that is, by implication, the sphalerite was related to latestage faulting. 

The deposits have been considered by most authors 

(Brown, Grogan and Bradbury, Heyl and associates) as 

epigenetic, with the ore elements mostly carried by hot 

connate water that was heated by deep-seated igneous 

activity, and carried upward along the faults to their 

present location. Some of the ore elements presumably 

were contributed to the connate water from deep-seated 

igneous activity. 

One group (Amstutz and associates) suggested a 

syngenetic origin, and one writer (Brecke) suggested that 

connate water picked up the ore elements from the sediments and moved them laterally into the district from the 

southwest, without recourse to igneous activity. 

Fluorspar reserves in the Illinois-Kentucky district are 

substantial. No comprehensive survey of reserves has been 

made since 1956 ("Fluorspar Reserves of the United States 

Estimated," press release, Office of Minerals Mobilization 

and U.S. Geol. Survey, November 23, 1956). However, a 

brief survey of the major producers in the district suggests 

that, under present economic conditions, new reserves 

found have at least been equal to production since 1956, 

and total reserves are probably adequate for at least 15-20 

years. 

New finds of near-surface gravel spar deposits probably 

will be rare, and there has been only slight to moderately 

encouraging results from deep exploration (deeper than 

1,000 feet-300m). Large numbers of faults within the 

district have not been adequately tested at intermediate 

depths or even shallow depths in places, suggesting that 

the district has much additional potential and will be a 

source of fluorspar for many years. Currently, exploration is increasing, and several new discoveries have been 

made in the last several years. 

Large quantities of low-grade fluorite in the breccias at 

Hicks Dome are too lean to be mined now; under more 

favorable economic conditions and with possible 

byproduct production, large-scale mining operations on 
74 GEOLOGY AND RESOURCES OF FLUORINE 

the breccias might be undertaken in the future. Mining of 

the breccia ores at Hicks dome could increase substantially the resources of the Illinois-Kentucky fluorspar 

district. 

CENTRAL KENTUCKY 

The Central Kentucky district, covering more than 2,000 

mi2 (5,000 km2) in Boyle, Clark, Fayette, Garrard, 

Jessamine, Lincoln, Madison, Mercer, and Woodford 

Counties, has yielded about 30,000 tons of fluorspar over a 

period of many years; the largest production was made in 

194 7 (Sutton, 1953, p. 140), and the district in 1972 is 

inactive. Veins cut Middle Ordovician limestones along 

strike-slip and normal faults (Currier, 1923; Robinson, 

1931; Earl, 1959; Jolly and Heyl, 1964). The veins are 

localized along the Kentucky River fault zone astride the 

Lexington dome and the Cincinnati arch. Most of the 

nearly vertical veins trend approximately northerly and 

range in width from less than an inch (2.5 em) to about 6 

feet (2m). A few veins trend easterly or northeasterly. They 

have been mined to a depth of 220 feet (67 m). Lateral 

zoning in this district (Jolly and Heyl, 1964) consists of an 

inner two zones with fluorite and an outer zone of baritegalena-sphalerite. Textures range from coarse comb 

crystals in the inner zone to fine colloform layers in the 

outer zone. Fluorite, sphalerite, galena, barite, strontian 

barite, and calcite are major minerals. Celestite, 

strontianite, marcasite, pyrite, chalcopyrite, quartz, 

witherite, and ferroan dolomite are minor minerals. The 

vein walls are almost unaltered. The veins are epithermal 

fissure fillings and breccia replacements that formed in 

late Paleozoic time. 

Exploration in progress in 1972 in the Central Kentucky 

district was searching for sulfide-bearing breccia deposits 

similar to those in the Lower Ordovician carbonate strata 

of the Cumberland River vein district and the Central 

Tennessee district. The carbonate rock stratigraphy 

changes westward in central Kentucky across the 

Cincinnati arch and so lithologies are more like those in 

central Tennessee, making the probabilities of deposits 

similar to those in central Tennessee better on the eastern 

side of the arch. Widespread faults in the Central Kentucky 

district probably provided channels for easy flow of orebearing solutions and allowed formation of fissure veins. 

Bedded and breccia deposits more probably occur in areas 

sparsely faulted and still capped by unbroken semipermeable shaly beds. Such geologic conditions exist 

southward along the Cincinnati arch toward Tennessee 

and to a lesser extent northwestward toward Louisville, 

Ky. Probabilities are good for the development of new 

commercial deposits of fluorspar on the known veins, and 

for discovery of new fluorspar veins in the central part of 

the district. 

CUMBERLAND RIVER, KENTUCKY 

A northward extension of the Central Tennessee 

district, described below, lies along the Cumberland River 

in Monroe, Cumberland, and Russell Counties, Ky. (Jolly 

and Hey], 1968), where small veins containing traces of 

purple fluorite, but otherwise mineralogically identical 

with those in central Tennessee, have been prospected. 

These veins in Middle Ordovician limestones lie 30-50 

miles (50-80 km) northeast of the main Central Tennessee 

district in an area of good outcrops. Unquestionably they 

indicate an extension northeastward of the district, and a 

possible connection of the Central Tennessee district with 

the Central Kentucky district along the crest of the 

Cincinnati arch. Breccia fluorspar deposits similar to 

those in the Central Tennessee district may occur in 

quantity in the Lower Ordovician and lower parts of the 

Middle Ordovician carbonate strata in this Cumberland 

River vein district. 

TENNESSEE-NORTH CAROLINA-VIRGINIA 

CENTRAL TENNESSEE 

The Central Tennessee zinc-fluorspar-barite-lead 

district (Jewell, 1947; Maher, 1970) covers about 2,400 mi2 

(6,200 km2) in Smith, DeKalb, Putnam, Trousdale, 

Wilson, Davidson, Williamson, Rutherford, and Cannon 

Counties, and was the source of about 1,500 tons of handpicked flourspar in 1902-06, 1914-18, 1925-28, 1935-36, 

1942-43, and 1956. This district is on the Nashville dome, 

which is structurally connected by the Cincinnati arch to 

the similarly mineralized Lexington dome farther 

northeast. 

After the Illinois-Kentucky fluorspar district, the 

Central Tennessee district may have the largest fluorspar 

resource potential in the United States, occurring in stillunmined breccia blankets of fluorspar, barite, sphalerite, 

and calcite in Lower and Middle Ordovician carbonate 

rocks. Past production of fluorspar nevertheless was 

entirely from nearly vertical veins cutting Lower 

Ordovidian to Mississippian rocks; most deposits are in 

limestone of Middle Ordovician age. Igneous rocks are 

lacking in the district. The veins formed largely by fissure 

filling and replacement of breccia fragments; there is little 

evidence for replacement of the limestone walls. Mineralized faults, commonly having horizontal displacement, 

generally trend northeast; most northwest-trending faults 

are post-ore. Most veins are less than 3 feet (I m) thick but 

veins range in thickness from a few inches to 6 feet (2m) 

where the vein material consists of well-layered material, 

and to 15 feet (4.5 m) where the vein is a mineralized 

breccia zone. 

A few small bedded replacement bodies or pipes of 

fluorite have been mined or prospected here in the Middle 

Ordovician limestone. Nearly all the known deposits 

exposed at the surface were described by Jewell (1947). The 

vertical extent of some deposits is at least 200 feet (60 m). A 

few veins may extend for 1,000 feet (300m) in length. The 

veins consist chiefly of strontian barite, multicolored 

fluorite, sphalerite, galena, calcite, quartz, dolomite, and a 

little chalcopyrite and pyrite and their oxidation products. 

A few veins consist almost entirely of sphalerite and 
CENTRAL AND EASTERN UNITED STATES 75 

calcite. Analyses of vein material (Jewell, 1947, p. 21) show 

the following ranges: 3-86 percent CaF2 , 1-79 percent 

BaS04, 3-60 percent CaC03, less than 1-3 percent Si02. 

As on the Lexington dome, fluorite is the prominent 

mineral near the center of the Nashville dome, and the 

mineral zoning and paragenesis in these two districts are 

quite similar (Jolly and Heyl, 1964, p. 618). Some veins 

were worked also for lead, zinc, or barite, and possibly 

some of them may yield coproducts in the future. Most 

veins, however, are much too small to be important future 

producers. According to Jewell, the veins have never been 

adequately explored. They are regarded as lowtemperature hydrothermal deposits (Jolly and Heyl, 1964, 

p. 621; Jewell, 1947, p. 37) formed from heated saline 

brines in post-Carboniferous time. 

Large blanket and podlike breccia deposits of fluorspar, 

barite, sphalerite, and calcite have been found at depth in 

recent years in the Central Tennessee district during 

extensive exploration programs by many companies 

searching for zinc deposits similar to the large ones discovered by the New Jersey Zinc Company near Carthage, 

Tenn. In contrast to the overlying veins the deeper 

deposits are lead-free or lead-lean. In these deposits 

dolomite is sparse and replacement features uncommon, 

unlike the somewhat similar deposits in eastern Tennessee 

near Sweetwater. Fluorite, most of it colorless, cements 

breccia fragments of limestone, dolomite, and gray 

jasperoid. Several ages of breccia are known, but most of 

the mineralized breccia bodies are in the middle and upper 

parts of the Lower Ordovidian Kingsport Dolomite. Some 

bodies extend through the unconformity at the top of the 

Lower Ordovician rocks up into overlying Middle 

Ordovician limestones. Fluorite-bearing aureoles of 

potential byproduct value may exist around some of the 

zinc-rich ore bodies as well as around the fluorite breccia 

bodies. Large parts of the Central Tennessee district that 

are marked by small veins are still scarcely prospected; 

notable are the southern and southwestern parts along the 

crest of the Cincinnati arch. 

SWEETWATER, TENNESSEE 

According to Brobst ( 1958, p. 1 02), 

the Sweetwater district in parts of McMinn, Monroe, and Loudon 

Counties has yielded most of the barite mined in Tennessee. The barite 

occurs with fluorite, sphalerite, and pyrite in veins or shatter zones in the 

upper part of the Knox Group of Cambrian and Ordovician age and it is 

concentrated in the overlying residual clays. Only the residual barite 

deposits have been mined. Fluorite is generally absent in the residual 

deposits and no gravel spar is known, a fact that has largely obscured 

the true composition of the deposits: 

In bedrock the deposits contain almost as much fluorite as 

barite, and in places considerable sphalerite (Laurence, 

1939, 1960). D. A. Brobst (oral commun., 1972) confirms 

this widespread abundance of fluorite throughout the 

district wherever the unweathered primary deposits are 

exposed. Many of the bodies in the shattered zones are 

large, and except for the main minerals in them are 

geologically similar to the collapse breccia and 

disseminated zinc ore bodies of eastern Tennessee. In the 

main zinc deposits of Tennessee, barite and fluorite are 

sparse late minerals, but elsewhere in the zinc districts of 

the Appalachian Valley and Ridge province between 

Alabama and Pennsylvania all gradations of deposits 

occur from nearly pure sphalerite to barite (or baritefluorite). 

Deposits in the large Sweetwater district occur in three 

parallel northeast-trending belts of· limestone and 

dolomite separated by zones devoid of deposits. According 

to Brobst (1958, p. 102) the three belts of gently eastdipping Knox Group strata lie in nearly parallel fault 

blocks bounded by southeast-dipping thrust faults. 

Workable bodies of residual barite ore occur at irregular 

intervals along the three belts. Unlike fluorspar in the 

Central Tennessee district to the west, the fluorspar here 

was apparently dissolved during weathering and did not 

accumulate in the residual clays as did the barite (D. A. 

Brobst, oral commun., 1972). Thus the absence of 

fluorspar in the residual barite deposits does not indicate 

either its absence or its possible abundance in the bedrock 

deposits. In fact a possibility for exploration would be to 

test the bedrock beneath the leaner barite residual 

deposits to determine whether sparsity of barite indicates 

more abundant fluorite. 

The eastern belt is 20 miles (30 km) long and the other 

two belts are each 40 miles (65 km) long. Individual 

commercial deposits of barite extend over many acres, and 

zinc deposits are known in the district. The marked 

geologic similarity (including the same favorable strata) 

between the primary unweathered deposits and the huge 

zinc deposits of eastern Tennessee farther north suggests 

that a major fluorspar-barite (and in places zinc) resource 

potential exists here; it may be one of the larger deposits in 

the country. Careful exploration and evaluation of the 

primary deposits are required to determine whether they 

are economic in grade and adaptable to known milling 

techniques. 

DEL RIO, TENNESSEE-HOT SPRINGS, NORTH CAROLINA 

The Del Rio district in Cocke County of easternmost 

Tennessee and the Hot Springs district in Madison 

County of westernmost North Carolina are two parts of 

one mineralized area of barite and fluorite (Stuckey, 1942; 

Oriel, 1950; Ferguson and Jewell, 1951; Brobst, 1958). A 

moderate tonnage of barite has been produced from both 

districts and a small tonnage of fluorspar from the Del Rio 

district (Ferguson and Jewell, 1951). The mineralized area 

forms a belt that trends east for about 20 miles (30 km) 

across the crest of the Blue Ridge Mountains. The belt is 

about 10 miles (15 km) wide at its widest, which is in the 

Del Rio district. Many mines and prospects are in the 100-

mi2 (260 km 2) area. Most of the mining has been in residual 

deposits in deeply weathered zones. 

The rocks in the Del Rio district are gneiss, schist, and 

quartzite of the Snowbird Group, and the Sandsuck 
76 GEOLOGY AND RESOURCES OF FLUORINE 

Formation, all of Precambrian age (Brobst, 1958, p. 90), 

and clastic rocks of the Unicoi and Hampton Formations 

of Early Cambrian(?) age, the Erwin Formation of Early 

Cambrian and Early Cambrian(?) age, and the Shady 

Dolomite and shale of the Rome Formation of Early 

Cambrian age (Ferguson and Jewell, 1951, p. 12). These 

rocks occur in two overthrust sheets that have been thrust 

from the southeast. 

Minerals in the deposits are barite, fluorite, ankerite, 

dolomite, sericite, specular hematite, quartz (including 

jasperoid), pyrite, and copper minerals; in some places all 

these minerals are present, in others, only a few. Fluorite is 

found in most deposits, and in places exceeds 20 percent of 

the total. The ore bodies were probably deposited at higher 

temperatures than those that prevailed at Sweetwater, 

Tenn. 

Most of the primary deposits in the Hot Springs district 

in North Carolina are fissure veins in quartzite. In the Del 

Rio district, the primary deposits are of two other types: (I) 

replacement of finely granulated sheared gouge and 

breccia in thrust faults, and (2) cementation and replacement within tension fracture zones and along bedding 

planes and permeable beds. Some of the ore bodies of the 

second type are large and constitute an important resource 

of many tens of thousands of tons of barite and as much as 

20 percent fluorite that could be recovered by 

concentration mills. 

HAMME, NORTH CAROLINA-VIRGINIA 

The Hamme tungsten district is in the Piedmont 

province, almost centered along the North CarolinaVirginia State line between Vance County, N. Car., and 

Mecklenburg County, Va. High-temperature fissure veins 

occur near the granite-schist contact, mostly in granite 

(Espenshade, 1947; Parker, 1963). 

Tungsten-bearing veins lie in a northeast-trending belt 

about 8 miles (13 km) long. Individual veins range in 

length from a few feet to at least I ,000 feet (300m) and they 

extend to depths exceeding 1,000 feet (300 m). The 

principal minerals are quartz, huebnerite, scheelite, 

fluorite, garnet, apatite, sericite, rhodochrosite, topaz, 

pyrite, argentian galena, calcite, tetrahedrite, sphalerite, 

and chalcopyrite; a little gold is present. Fluorite is the 

most abundant mineral aside from quartz, but it has not 

been recovered as a byproduct even though it occurs in 

nearly every tungsten-bearing quartz vein. The fluorite is 

pale green, blue, and purple where fresh, but bleaches to 

white upon exposure to sunlight. 

Espenshade (1947, p. 7) reported that about 4 percent of 

fluorite was noted in the mill tailings in the early years of 

the Hamme mine. The deposits are large, and for about20 

years the Hamme mine was the largest tungsten mine in 

the United States. A substantial fluorspar resource is 

present in this district and fluorite could be recovered from 

the mill tailings and as a byproduct of mining when the 

mine is reopened. 

FABER, VIRGINIA 

A long vein of quartz, fluorite, argentian galena, 

sphalerite, and chalcopyrite produced some zinc, lead, and 

a small quantity of fluorite during 1905-19 in Albermarle 

County, 2 miles (3 km) east of Faber (Luttrell, 1966, p. 

46-47). The fissure vein trends northeast and lies in the 

western part of the Piedmont province in a heavily wooded 

area where outcrops are scarce. The vein occurs in a shear 

zone within biotite-chlorite-muscovite gneiss. Little 

effort, as far as is known, has been made to determine if 

other veins occur in the vicinity. 

OTHER DEPOSITS, VIRGINIA 

Appalachian-type deposits of barite, sphalerite, and 

fluorite are common in three parts of Virginia: (I) the Gate 

City-Lebanon area in southwestern Virginia, (2) the 

Marion-Austinville area in south-central Virginia, and (3) 

the northern part of the Shenandoah Valley of Virginia, 

where there are little-known fluorite veins and zincfluorite breccias near Woodstock and Lebanon Church at 

the northeastern end of the Timberville zinc district. 

The Gate City-Lebanon area includes a long discontinuous line of deposits of sphalerite, barite, and fluorite 

that trends east-northeast for at least 50 miles (80 km) 

through Scott, Russell, Tazewell, and Bland Counties. 

Fluorite, locally forming as much as 20 percent of a 

deposit, occurs with the sphalerite and barite in mineralized breccia zones in Kingsport Dolomite of Early 

Ordovician age similar to those at Sweetwater, Tenn. 

Residual barite deposits occur in places and the entire belt 

needs re-examination in terms of a possible fluorspar 

potential similar to that in the Sweetwater district, 

Tennessee. 

An area· of similar deposits extends at intervals from 

Marion, Virginia, to the Austinville-Ivanhoe zinc-lead 

district farther east. Some of the western deposits near 

Marion contain abundant fluorite. They consist of baritefluorite-sphalerite breccia bodies. West of Marion, for 

example, is the Myers deposit of coarse platy white barite, 

colorless and purple fluorite, pale-yellow sphalerite, and a 

little pyrite, in the upper part of the Kingsport Dolomite. 

Fine-grained gray dolomite and black and gray jasperoid 

are the main gangue minerals. The mineralized zone is in a 

vertical body of collapse breccia alined along the crest of 

an anticlinal nose. 

In the eastern parts of this area south of Austinville and 

Ivanhoe similar barite-fluorite deposits are known, but 

little prospected, in the Shady Dolomite and in the Unicoi 

Formation, of Cambrian and Cambrian(?) age 

respectively; deposits in Grayson County are in Precambrian gneiss, schist, granite, and volcanic rock. At the 

Poole barite prospect on the east bank of the New River 5 

miles (8 km) east-northeast of Independence, a fissure vein 

as much as 16 inches (40 em) wide of fine-grained barite, 

epidote, chlorite, fluorite, and quartz has been prospected 

by three shallow shafts (Edmundson, 1938, p. 48-49). 
CENTRAL AND EASTERN UNITED STATES 77 

Another locality is the Simmerman prospects, 5 miles (8 

km) east of Ivanhoe Ferry, in the Cambrian Shady 

Dolomite. There, in old pits, where the iron ore is 

undoubtedly a limonite gossan, brecciated dolomite 

outcrops contain sphalerite, galena, fluorite, barite, cherty 

quartz, and calcite (Luttrell, 1966, p. 119). 

Fluorite occurs in small quantities throughout the 

Timberville zinc district of northern Virginia in Augusta, 

Rockingham, and Shenandoah Counties. The mineral is 

abundant at the Tusing prospect 4.9 miles (7.9 km) S. 82° 

W. of Mount Jackson (Herbert and Young, 1956, p. 36). 

Here coarse purple fluorite occurs in disseminations 

associated with yellow sphalerite and calcite throughout a 

bed of crystalline dolomite. Between 1956 and 1965 a 

prospect shaft was dug on the property, and a bin was 

filled with a few tens of tons of sorted fluorite-sphalerite 

ore (C. H. Maxwell, 1972, oral commun.). Maxwell 

estimated that the sorted coarse-grained ore contained 

about 50 percent purple, colorless, and pale-yellow 

fluorite, 30 percent honey-yellow sphalerite, and the rest 

barite and calcite. 

About 8 miles ( 13 km) northeast of the Tusing prospect 

is the most probable location of the Barton fluorspar vein, 

which is reported to be many feet wide and to trend 

northerly (Silliman, 1821, p. 243-244). This vein, which 

was described and then forgotten in the early 19th century, 

is reported to be in limestone at the very foot of the 

southeast slope of Little North Mountain, northwest of 

Woodstock. The vein is reported to consist of purple 

fluorite and calcite. It is on a small ridge and between two 

walls of limestone. At the time of the discovery of the vein 

prior to 1820, fluorspar had little or no value and the exact 

location of this vein is now lost. 

About 10 miles (15 km) northeast of the Barton vein, and 

0.5 mile (0.8 km) northwest of the village of Lebanon 

Church in northernmost Shenandoah County, a similar 

deposit of fluorspar was found in the 1960's by C. H. 

Maxwell (oral commun., 1972). It lies at the southeast foot 

of Little North Mountain on a small knoll of Paleozoic 

limestone. Coarse pieces of residual colorless and yellow 

fluorite are abundant in the yellow clay soil atop the knoll 

between two low outcrops of northeast-trending 

limestone. 

The above three deposits of fluorspar found at intervals 

along a 20-mile (30-km) trend at the foot of Little North 

Mountain may indicate a fluorspar district of commercial 

importance. Similarly occurring and equally little-known 

occurrences of sphalerite near Timberville, farther south, 

led to the exploration and development of the Timberville zinc district in the early 1950's. 

ALABAMA 

Deposits notably similar to those in the Sweetwater 

district, Tennessee, are known in slightly older carbonate 

rocks in Alabama at the Sinks district, Bibb County and at 

the Gilley (or Gilly) deposit in northeastern Alabama in 

Calhoun and Cherokee Counties. The Gilley deposit has 

produced a small quantity of fluorspar from veins and 

other concentrations in Conasauga Limestone of 

Cambrian age (O'Neill, 1950). This deposit and several 

other residual barite deposits and fluorspar occurrences in 

Alabama and in nearby Georgia (Brobst, 1958, p. 106; 

Worl and others, 1974) need reevaluation in respect to 

possible similarities to the Sweetwater, Tenn., deposits. 

MISSOURI-ARKANSAS-CENTRAL TEXAS 

SOUTHEAST MISSOURI 

The Precambrian magnetite deposits being mined in 

1972 at Pilot Knob and Pea Ridge, Mo., and the recently 

closed mine at Iron Mountain, all contain fluorite and 

fluorapatite. Both fluorine minerals are locally abundant 

in these large deposits. For example, the initial new shaft 

put down in recent years at Pilot Knob cut a fluoritechalcopyrite-magnetite body of sizable tonnage (P. W. 

Guild, oral commun., 1967). Elsewhere in the district the 

abundance of purple and colorless fluorite and associated 

apatite is apparent and in parts of the Pilot Knob ore body 

the mineral may constitute as much as a few percent of the 

ore. 

The same potential for byproduct fluorite and copper 

concentrates exists here as in the Adirondack Mountains. 

The partly developed Boss iron-copper deposit, as well as 

the Bourbon and Sullivan magnetite deposits, should also 

be examined for fluorite potential. 

OTHER DEPOSITS, MISSOURI AND ARKANSAS 

Fluorite occurs elsewhere in the Precambrian of southeast Missouri. Fluorite is found with calcite and apatite in 

a veinlet in a granite quarry at Granite, north of Ironton; 

disseminated fluorite is reported in this same granite. 

Fluorite occurs in high-temperature Precambrian veins 

with quartz, topaz, cassiterite, wolframite, and silver-rich 

galena at the Einstein silver-tin mines southwest of 

Fredrick town. 

Coarse yellow fluorite and pink platy barite occur in 

large gas cavities in a Devonian kimberlite breccia on the 

O.K. Cash farm southeast of Avon, Mo. (Zartman and 

others, 1967). The kimberlite, which contains many limestone fragments, is fluorine rich. Fluorite is abundant 

enough to suggest that the 70 or so other Devonian 

intrusives near Avon should be examined for fluorite. 

Fluorite is locally abundant in the Magnet Cove and 

Fourche Mountain, Arkansas, alkalic igneous rock 

complex, and in small veins in the southern Ouachita 

Mountains, Arkansas. A search might be warranted on the 

margins of these complexes and near the contacts of the 

other alkalic syenites in central Arkansas for fluorite 

deposits of commercial size, especially where the wall rocks 

are limestone or dolomite. 

LLANO UPLIFT, CENTRAL TEXAS 

Fluorite deposits and occurrences are common in Pre-
78 GEOLOGY AND RESOURCES OF FLUORINE 

cambrian granites and gneisses in the Llano uplift west of 

Austin (Paige, 1911), particularly northwest of Austin at 

Burnet where a small quantity of fluorspar was produced 

in 1943. The deposits are mostly disseminations of fluorite 

and clusters of small fluorite veins in granite and in gneiss. 

The main deposits form a small cluster 4-7 miles (6.5-11 

km) west of Burnet along the north fork of Spring Creek. 

Fluorite and topaz are also common in the complex 

pegmatites of the Llano uplift such as those on Barringer 

Hill. Fluorite is disseminated in the granite of Opaline in 

Llano County and in the Oatman Creek Granite of Stenzel 

(1932) along Honey Creek in Mason County. The Llano 

uplift appears to be a favorable area in which to search for 

commercial fluorite deposits. 

A topaz placer occurs in the Llano uplift of central 

Texas (Paige, 1911). The bedrock source of the coarsegrained white topaz has not been found, but it is probably 

in pegmatite. The deposit, which has been prospected but 

not mined, is near Streeter in Mason County. The 

occurrence of topaz in pegmatites and granites elsewhere 

in the uplift suggests that other such topaz placers may 

exist. 

NEW YORK 

ADIRONDACK MOUNTAINS 

Nearly all the Precambrian magnetite deposits of the 

Adirondack Mountains of New York contain fluorite, but 

in most deposits fluorite is a sparse mineral. Certain types 

of skarn magnetite deposits, however, contain locally 

abundant fluorite; in places the mineral forms 5-60 

percent of the deposit. Types of skarns that may contain 

locally abundant fluorite (according to Leonard and 

Buddington, 1964, p. 33-35) are clinoamphibole skarn, 

biotite skarn called "skol," (in which the mica is in 

contorted streaks, masses, and selvages), and a modified 

scapolitic skarn, which is derived by further metamorphism from the other types. All types except the 

scapolitic fluorite-bearing skarn are associated with 

magnetite deposits. Some of the larger fluorite-bearing 

deposits are the Parish, Trembley Mountain, andJayville, 

all in the St. Lawrence magnetite district, the Palmer Hill 

iron deposits in the northeastern Adirondack Mountains, 

and the Mineville deposits in the southeastern Adirondack 

Mountains. 

Many of these skarn magnetite deposits are large. They 

range in length from 800 to 4,000 feet (250-1,200 m); 

generally they are 1,000-2,000 feet (300-600 m) long and 

30-65 feet (10-20 m) wide and extend to depths greater 

than 500 feet (150m) (Leonard and Buddington, 1964, p. 

39-40). Deposits of this size may contain up to several 

million tons of iron ore. Many deposits are much smaller. 

An example of a skarn magnetite deposit that is rich in 

fluorite is the Jayville deposit, 1.25 miles (2 km) east of 

Kalurah, St. Lawrence County, in the western Adirondack 

Mountains. The mine has yielded several tens of 

thousands of tons of magnetite ore; associated with the 

magnetite ore are supergene hematite, vonsenite (ferrousferric borate), fluorite in dark mica skarn (skol), pyroxeneamphibole skarn, and quartz-bearing amphibole skarn. 

Parts of the amphibole skarn and the iron ore are rich in 

fluorite; this type of skarn is as much as a few feet thick and 

ranges from 20 to 60 percent fluorite (Leonard and 

Buddington, 1964, p. 134, 142). If the iron deposit is mined 

again, fluorite and vonsenite (borate) should be considered 

as coproducts. 

The Parish fluorite-bearing iron deposit is about 6 miles 

(10 km) east of Degrasse in the central part of St. Lawrence 

County. The deposit is probably 4,000-5,000 feet 

(1,200-1,500 m) long, has an average thickness of 55 feet 

(17m), and has been explored by drilling to depths of 600 

feet (180 m). The deposit consists of magnetite-hematite 

ore with spessartite garnet, chalcopyrite, bornite, pyrite, 

and fluorite. In places the fluorite constitutes several 

percent of the ore (Leonard and Buddington, 1964, p. 223 ). 

Potentially the deposit has several valuable coproducts 

including the fluorite. If methods now applied elsewhere 

to recover the magnetite and hematite were used, and in 

addition copper sulfide and fluorite concentrates were 

recovered, this large deposit would have more value than 

deposits from which iron alone is recovered. 

At Mineville, rare-earth fluorapatite, rare-earth fluocarbonates (including bastnaesite), and fluorite occur in 

several deposits (McKeown and Klemic, 1956). Large 

quantities of these minerals are already partly concentrated in the mill tailings, making a potential ready source 

of fluorine and thorium- and yttrium-bearing rare earths. 

North of Mineville, at Palmer Hill, fluorite and 

fluorapatite are abundant in the iron deposits, and in one 

mine an undeveloped vein of fluorite is reported adjacent 

to the magnetite ore. 

The magnetite deposits of the Adirondack Mountains 

should be considered a major potential source of fluorine, 

mostly as a coproduct or byproduct of iron mining. To 

date the fluorite has not been recovered. The potential 

tonnage of fluorite in the magnetite deposits is very large, 

probably exceeding a million tons. 

OTHER DEPOSITS 

Fluorspar has been produced from only two of several 

fissure veins in the Rossie vein district of northern New 

York. The production has not been large, and the vein 

system only locally contains commercial concentrations of 

green and colorless fluorite. More commonly, galena and 

sphalerite are the main ore minerals. The veins, which are 

large and wide, are in vertical faults, mostly of northwesterly trend on the south flank of the Frontenac arch. 

The faults have large strike-slip components, and are postPrecambrian in age. The deposits are low temperature and 

contain coarse-grained minerals. Galena in the veins is 

radiogenic. In these respects and in all others, the veins can 

be classified as Mississippi Valley-type. The veins in the 

district are not well known and have not been prospected 
CENTRAL AND EASTERN UNITED STATES 79 

extensively; a belt may extend northwestward from 

Lowville well into southern Ontario to the Madoc 

fluorspar district. The Rossie district, though of secondary 

resource potential, should be reevaluated in terms of its 

fluorspar possibilities. 

NEW ENGLAND 

CHESHIRE COUNTY-WESTMORELAND, NEW HAMPSHIRE 

The most productive fluorspar district in New England 

is about 2.5 miles (4 km) southwest of Westmoreland, 

Cheshire County, where about 8,000 tons (7,262 t) was 

produced in 1911-23 and 1935-38 (Bannerman, 1941 ). The 

deposits are 2-3 miles (3-5 km) southeast of the 

Connecticut River valley in granite gneiss overlain by 

hornblende schist, quartzite, and staurolite-mica schist. 

Lenticular fluorite-quartz veins are found near the contact 

with overlying hornblende schist. Blue-green fluorite 

occurs in lenses, pockets, and fine-grained intergrowths 

with quartz, calcite, and barite; streaks of sulfide minerals 

are rare. The sulfide minerals are chalcopyrite, galena, 

pyrite, sphalerite, and bornite. The small production 

came from shallow workings on seven veins. An ore 

sample from a dump contains 35 percent CaF2 and 60 

percent Si02 (Bardill, 1946, p. 5). A vein intersected by a 

drill hole 150 feet (45 m) deep contained only about 2 

percent fluorine and less than I percent barium. 

These deposits and others in New Hampshire may be 

related genetically to Devonian granites, as Cox (1970, p. 

D3-D4) suggested for fluorite-bearing deposits associated 

with the Conway Granite. Possibly, however, the 

structural position of the Cheshire County-Westmoreland 

district in the Connecticut Valley graben, on trend with 

mineralogically similar Triassic or younger veins in 

Massachusetts, indicates a Triassic or younger age for the 

veins in southern New Hampshire. The small veins of 

fluorite nearby at Putney, Vt., are probably genetically 

related. 

The Cheshire County-Westmoreland veins were 

productive even without milling; the fluorspar was 

concentrated by hand sorting. Thus only the coarsest and 

purest ore could be shipped. Bannerman's (1941) description of the veins indicates that only the richest parts of the 

known veins were mined, and only to shallow depths. 

Some lower grade veins amenable to milling were not 

mined, and he considered indications good that the veins 

extended to greater depth. Thus the district may have a 

future as a potential resource of moderate size. 

NORTH CHATHAM, NEW HAMPSHIRE 

Granite pegmatites near the village of North Chatham 

contain fluorite and topaz along with beryl, lepidolite, 

and muscovite. Locally, the fluorite is so abundant that a 

few tons was mined many years ago (Morrill, 1951). The 

pegmatites are possibly related to the Conway Granite of 

the White Mountain Series. Many nearby pegmatites in 

western Maine contain fluorite and topaz. 

LONG HILL (TRUMBULL)-MONROE, CONNECTICUT 

One of the first producers of fluorspar and tungsten in 

the United States is north of Bridgeport in southwestern 

Connecticut. In 1837 fluorspar was mined from a vein on 

the southern crest of Long Hill in the Township of 

Trumbull and used as a flux to smelt copper ores 

(Hatmaker and Davis, 1938, p. 17). Coarse-grained green, 

colorless, and pale-purple fluorite occurs in a few large 

east-trending fissure veins of fluorite, topaz, quartz, 

margarite, margarodite, wolframite, scheelite, and arsenopyrite. Pegmatites a few hundred feet north of the veins 

contain coarse fluorite in miarolitic cavities, and fluorite 

is reported also to occur with scheelite in marble and in 

a skarn contact zone between the Straits Schist and the 

Collinsville Formation of Crowley (1968). Fluorite occurs 

north of Long Hill in smaller quantities at Lanes mine, I 

mile (1.6 km) west of Monroe village. There it is in a quartz 

vein with sparse tungsten and silver-lead, bismuth, and 

arsenic minerals. A few miles southeast of these deposits is 

the Pinewood Adamellite of a quartz monzonite (or 

adamellite) stock, which contains disseminated fluorite 

(Crowley, 1968). Intrusives of this type at depth may have 

been the source of the fluorite on Long Hill. Although this 

area is favorable for other fluorspar deposits, and fluorite 

is still available in the known veins, Long Hill is now a 

State Park, and both it and Lanes mine are being engulfed 

by the suburban area of southern Connecticut. 

LONG ISLAND, BLUE HILL BAY, MAINE 

A hundred-foot-wide tactite zone of eastward trend more 

than a mile ( 1.5 km) long crosses the northern third of 

Long Island, southeast of Blue Hill, Maine. The zone is 

part of the northern tactite-bearing contact between biotite 

granite and Ellsworth Schist. The tactite contains 

appreciable scheelite, molybdenite, apatite, a beryllium 

mineral, and coarse crystals of green fluorite. A very small 

quantity of the fluorite was mined in 1838 and sold to 

apothecary shops (Hatmaker and Davis, 1938, p. 17). The 

contact zone potentially may be an important resource of 

the coproducts fluorspar, tungsten, molybdenum, and 

beryllium. 

OTHER DISTRICTS AND DEPOSITS OF THE 

CENTRAL AND EASTERN UNITED STATES 

Parts of the Midwest region, other than those already 

described, that should be examined for possible new 

fluorspar districts are: (I) northern Ohio in the vicinity of 

Toledo where fluorite is known in limestone quarries on a 

structural dome; fluid-inclusion studies by Edwin 

Roedder (oral commun., 1970) indicate that the fluorite 

was deposited by hot concentrated brines and therefore 

may be present in substantial deposits; (2) Serpent Mound 

cryptoexplosion structure in Adams and Highland 

Counties, southeastern Ohio, where some fluorite and 

barite cement the breccias in places; (3) southern Indiana, 

west of Louisville, Ky., where a few minor fluorite 
80 GEOLOGY AND RESOURCES OF FLUORINE 

occurrences are known in limestone quarries-possibly 

indicative of an undiscovered district; ( 4) many minor 

occurrences of fluorite, barite, sphalerite, and galena in 

and near the Ste. Genevieve fault zone of southeast 

Missouri and southern Illinois, which also may be an 

undiscovered Illinois-Kentucky-type fluorspar and sulfide 

district. 

Fluorite is a common mineral in many of the other 

southwestern Virginia barite and zinc deposits, including 

a cluster in the vicinity of Roanoke. Indeed, Edmundson 

(1938, p. 12) stated that "fluorite was identified in all of the 

barite areas [in Virginia], being particularly abundant in 

the deposits of the Appalachian Valley and Ridge 

province.'' Thus a reexamination of all the barite deposits 

(and some of the zinc deposits) in terms of fluorspar 

potential in the Valley and Ridge province may be 

warranted. Similarly, the Falls Branch barite-zinc district 

and the Green County residual barite area (Brobst, 1958, p. 

115) might also be reexamined for fluorite in the bedrock 

deposits. Some similar possibilities exist in the same 

province in northwestern Georgia and northeastern 

Alabama. 

Fluorite occurs in some abundance in at least two of 

several small veins in Paleozoic carbonate rocks in the 

Great Valley extension of the Shenandoah Valley in the 

triangular area between Waynesboro, Chambersburg, and 

Mercersburg, Pennsylvania. Geologically these littleknown deposits resemble those to thP south in Virginia. 

Some granitic and volcanic rocks in Virginia and North 

Carolina contain abundant disseminated fluorite. These 

igneous rocks may indicate undiscovered fluorite deposits 

nearby. Notable examples are the granites of Browns 

Mountain and Beach Mountain in western North Carolina, the Grayson Granodiorite Gneiss and the Mount 

Rogers Formation in the southern Blue Ridge province of 

Virginia, and the Petersburg Granite in the eastern 

Virginia Piedmont (W. C. Overstreet, oral commun., 

1972). 

In the Piedmont many complex pegmatites are enriched in fluorine minerals, either fluorite or topaz; 

examples are known in the Rockford area, Alabama, at 

Amelia, Va., near Sykesville, Md., in the lower Connecticut Valley, at Long Hill, Conn. (p. 79), and in western 

Maine and eastern New Hampshire. These pegmatitic 

occurrences are generally not economic. 

Contact zones of the Triassic diabases of Virginia, Mary· 

land, Pennsylvania, Connecticut, and Massachusetts, and 

genetically related magnetite, copper, and silver-lead-zinc 

deposits, in places contain small quantities of fluorite. 

Locally, as in the northern part of the Connecticut Valley 

of Massachusetts, some veins contain sufficient fluorite 

and barite to be of commercial interest. Felsic and mafic 

syenites of northern New Jersey also contain disseminated fluorite, and some fluorite has been deposited in adjacent limestones and in the Franklin zinc ore body along 

the dike contacts. 

Fluorite is a common mineral in many of the skarn iron 

and zinc deposits of the New Jersey Highlands province, 

which is underlain by Precambrian gneisses, schists, 

skarns, and marbles (Worl and others, 1973). The highlands extend from west of Reading in eastern Pennsylvania northeastward through New Jersey into southeastern New York in the vicinity of West Point. In no part of 

this province are commercial fluorite deposits known, but 

in places fluorite associated with other fluorine-bearing 

minerals makes major bodies of fluorine-enriched rocks. 

Such rocks are most abundant in the marble and skarn 

belts on the northwest side of the highlands. 

Barite deposits of the Piedmont province of Virginia, as 

well as similar deposits in the Kings Mountain district of 

North Carolina, contain some fluorite (Edmundson, 

1938). As fluorite has no doubt been dissolved out of the 

residual deposits which were mined for barite, the possibilities of fluorite in quantity in the unmined bedrock 

deposits should be examined. 

Fluorite is a common mineral in the high-temperature 

small hydrothermal deposits of the Pawtucket area of 

northeastern Rhode Island. These deposits were mined 

long ago for copper and perhaps gold. They contain-in 

addition to fluorite-garnet, magnetite, scheelite, 

molybdenite, chalcopyrite, galena, and sphalerite (Quinn, 

1971, p. 58). Similar small quantities of fluorite are found 

in the gold-silver-lead-zinc-copper deposits of Deer Isle, 

Penobscot Bay, Maine. 

Other potential sources of fluorine in the Central and 

Eastern United States are topaz, fluorapatite, rare-earth 

fluocarbonates, and magnesium-iron silicate-fluoridehydroxides (chondrodite, humite, and norbergite), as well 

as commercial phosphate deposits. 

Topaz most commonly is associated with complex 

pegmatites, but not in commercial quantities. Such 

complex pegmatites occur throughout the Appalachian 

metamorphic belt from Maine to Alabama, and in central 

Texas. Notable occurrences are the pegmatites in Oxford 

and Kennebec Counties, Maine, and in New Hampshire 

on Baldface Mountain in Carroll County, where topaz 

occurs with beryl and lithium mica. Similar pegmatites 

are known near Amelia, Va., where very large white 

crystals of topaz occur in the cores of the Morefield and 

Rutherford complex pegmatites. Coarse tin-bearing 

quartz veins that contain topaz are found at Rockford, 

Coosa County, Ala., and in the Llano uplift of central 

Texas. 

Topaz most commonly is associated with complex granite pegmatites, but not in commercial quantities. Such 

kyanite, andalusite, pyrophyllite, and diaspore, and in 

high-temperature veins containing gold, tin, and tungsten 

minerals. In the Central and Eastern United States largt: 

veins and replacement masses of topaz in potentially commercial quantities occur in the Appalachian metamorphic belt, southeast Missouri, and the Llano uplift of 

Texas. 
CENTRAL AND EASTERN UNITED STATES 81 

Appreciable topaz occurs in fissure veins, some consisting of nearly pure, coarse, gray topaz and others 

consisting of pale-blue topaz crystals, with fluorite and 

scheelite, on Long Hill near Trumbull in southwestern 

Connecticut (Crowley, 1968). A similar but less-known 

occurrence is near Willimantic in eastern Connecticut, 

where topaz associated with fluorite, columbite, and 

scheelite is disseminated and in small veins in gneiss. 

One of the largest known deposits of topaz is at the 

Brewer gold mine, 1.5 miles (2.4 km) northwest of Jefferson, Chesterfield County, S.C. More than 700 tons of topaz 

was mined there before August 1941 (Fries, 1942) for 

experimental refractory purposes. At the Brewer mine, 

fine-grained rhyolite tuff and breccia have been metamorphosed to quartz-sericite schist. In places the schist is 

completely silicified and contains pyrite, gold, and topaz. 

The topaz forms irregular replacement bodies ranging in 

width from less than an inch (2.5 em) to 10feet (3m). Some 

topaz is in large veins and in veinlets; other topaz is disseminated in the schist associated with pyrite and gold 

(Pardee and Park, 1948, p. 106-111). 

The topaz contains 13-14 percent fluorine. The district 

contains probable reserves of 106,000 tons of rock averaging 15 percent topaz (Fries, 1942) or about 16,000 tons of 

topaz; some byproduct gold is present. In addition, 

possible reserves of 194,000 tons of similar grade topazbearing rocks might contain 0.05 ounce of gold per ton. 

The topaz very closely resembles slightly stained vein 

quartz and can be distinguished only with difficulty from 

it by a specific gravity greater than that of quartz and by the 

dull appearance of its weathered surfaces. A placer of topaz 

occurs downslope from the replacement deposits. 

Similar topaz deposits occur with pyrophyllite that is 

mined at Bowlings Mountain, Granville County, and at 

Corbett, Caswell County, N.C. At Bowlings Mountain 

large veins and bodies of massive topaz occur with pyrophyllite and andalusite in Paleozoic sericite schist. At Corbett large veins and disseminations of topaz occur with 

kyanite in metavolcanic schist. Possibly some of the North 

Carolina topaz could be recovered profitably from 

material mined for pyrophyllite if there were a market for 

the topaz. 

Near Rockford, Coosa County, Ala., massive finegrained topaz occurs in tin greisens and quartz veins in the 

extensive but not very productive Rockford tin district. A 

substantial tonnage of topaz could be recovered by 

concentration. 

Very fine grained gray topaz is abundant in greisens in 

vein walls of several tin, tungsten, and silver-lead veins of 

the Einstein silver district at Silver mines, southwest of 

Fredricktown, Madison County, Mo. Fluorite (p. 77) 

occurs in these veins also, and the two minerals together 

may constitute a potential fluorine resource especially if 

recovered as a byproduct of the high-value metallic 

minerals of the veins. 

Fluorine-bearing minerals fluorapatite (nonsedimentary), chondrodite, humite, norbergite, doverite, and 

bastnaesite, in some places occurring alone but commonly 

with two or more associated together, form a largetonnage potential source of fluorine, if the need should 

arise for such lower-grade materials or if extractive technology improves. A few deposits of these minerals are very 

large and could supply substantial quantities of fluorine. 

Recently fluorapatite has been separated and discarded 

from metalliferous deposits at Mineville, N.Y.; Dover, N. 

J.; Piney River, Va.; Pea Ridge and Pilot Knob, Mo.; and, 

to a lesser extent, at Sterling Hill, N. J. Some of the larger 

deposits and the main minerals present are listed in the 

following table. 

Deposit Location Main minerals 

New York 

Palmer Hill mines....... Ausable. ....... .. ... . ....... .. Magnetite, fluorite, 

fluorapatite. 

Mineville iron mines ... Mineville .................... Magnetite, fluorite, 

rare-earth fluorapatite, bastnaesite. 

Trembley Mountain ..... St. Lawrence County .. Magnetite, flourapaTilly Foster mine ......... Brewster, Putnam 

County. 

Mahopac mines ............ Mahopac, Putnam 

County 

O'Niell mine ................ Monroe, Orange 

Amity-Edenville 

marble quarries. 

County. 

Edenville, Orange 

County. 

New Jersey 

tite, fluorite. 

Magnetite, chondrodite, humite, fluorite, norbergite. 

Do. 

Magnetite, fluorapatite, chondrodite. 

Chondrodite, fluorapatite. 

Rudeville marble Rudeville, Sussex Chondrodite, fluorquarries. County. apatite. 

McAfee marble McAfee, Sussex Norbergite, fluoraquarry ....................... County. patite. 

Sterling Hill zinc Sterling Hill ............... Chondrodite, norbergmine. ite, fluorapatite, 

fluorite, franklinite. 

Franklin zinc mine . . .. .. Franklin...................... Do. 

Scrub Oaks iron mine .. Dover .......................... Magnetite, zircon, 

doverite. 

Canfield apatite mine ..... do............................... Fluorapatite, magnetite. 

Hurdtown apatite Hurdtown, Morris Fluorapatite. 

mine County. 

Pennsylvania 

Harvey's marble 

quarry. 

Brinton's Ford near Chondrodite. 

West Chester. 

Virginia 

Nelsonite dikes ............. Piney River, Ilmenite, apatite. 

Nelson County. 

All these occurrences except Piney River, Va., are in Precambrian skarns. Almost all are in the Adirondack 

Mountains, in the New Jersey Highland province, or in 

the Piedmont province. Many others undoubtedly exist 

and could be located by a detailed field or literature search. 

Some of the quarry occurrences, such as those in the marble quarry at McAffee, N. J ., contain substantial tonnages 

of minerals such as norbergite that could be quarried, 

milled, and concentrated on a large scale. 
82 GEOLOGY AND RESOURCES OF FLUORINE 

FLUORINE IN PHOSPHATE DEPOSITS 

By J. B. CATHCART 

Fluorine in sedimentary phosphate deposits is considered here separately as a type distinct from the epigenetic flu orin~ deposits described in detail in preceding pages. 

Economic phosphate deposits in the United States are 

confined to sedimentary phosphorites of Ordovician age 

in Tennessee and Alabama, of Permian age in the Western 

States, of Miocene age in North Carolina, Georgia, and 

South Carolina, and of Miocene and Pliocene ages in 

Florida (fig. II). Total reserves are billions of tons of phosphate rock containing 28-38 percent P 20 5 and more than 3 

percent F. 

Some fluorine is being produced in Florida as a byproduct of manufacture of chemical fertilizer from phosphate rock, and probably much more will be produced in 

the future (Sweeney, 1971). In January 1971, at the time of 

a field investigation in Florida by the author, phosphate 

companies reported that all the phosphate chemical 

plants there were recovering at least part of the fluorine 

produced during chemical or thermal treatment of phosphate rock. 

Production of phosphate rock in the United States in 

1970 was about 37.6 million short tons, a decline for the 

second straight year. Production data, and tonnages of 

phosphate rock by major uses, are shown in the following 

table. 

Production and uses of phosphate rock, 1970, in millions of short 

tons 

[Data from U.S. Bureau of Mines Mineral Industry Surveys-Phosphate Rock, Crop Year 

Annual, November 1970] 

PRODUCTION 

Florida (Includes land-pebble, Northern Florida field, and 

phosphate rock so treated contained about 875,000 short 

tons of fluorine, assuming an average fluorine content of 

3.5 percent in the rock, not all of which was liberated in 

gaseous effluent. Siems (1951, p. 409) indicated that about 

one-third of 'the fluorine is liberated during the manufacture of ordinary superphosphate, and phosphate 

companies indicate that this figure is approximately 

correct for the process used in chemical plants in Florida. 

About two-thirds of the fluorine evidently combines with 

calcium and does not go off in the gaseous effluent. 

The total amount of fluorine currently being produced 

from phosphate rock is not known. Effluent gases containing fluorine are treated to remove as much of this 

element as possible (to avoid air pollution), mainly by 

passing the effluent through powdered limestone. The 

fluorine in the gas combines with calcium in the limestone to form CaF2, but this fluorite was so finely divided 

that early attempts to recover it were not successful, and 

the material was discarded as waste. In 1972 several companies were making aluminum fluoride (AlF3 ) and artificial cryolite (Na 11AIF6 ) from the hydrofluosilicic acid 

derived from the fluorine in the gas (seep. 84). 

Partial chemical analyses of phosphate rock given 

in the following table represent deposits that were 

being mined in 1972. 

Partial chemical analyses, in percent, of phosphate rock from deposits 

in the United States 

[U.S. Geological Survey analysts: P20 5 by G. D. Shipley and Winona Wright, F b} Johnnie Gardner, AI20! by H. H. Lipp and Wayne Mountjoy, Fe and CaO by Viole1 Merritt and Johnnie &ardner, and Si02 by W. D. Goss, H. H. Lipp, and Elsie Rowe] 

P~5 ....... .. 

Western 

U.S.t 

Northern 

Florida· 

Southern 

Georgia2 

33.2 

North Florida land-pebble district Tennessee& Carolina3 

Pebble< Concentrate 

29.7 31.4 34.5 32.8 

North Carolina) ........................................................................ . 29.7 CaO ....... . 30.5 

44.0 

3.1 

11.9 

1.7 

1.1 

47.0 46 .. 2 46.3 49.7 46.1 

Tennessee (Includes mines in northern Alabama) ...................... . 3.0 F ........... .. 3.8 3.6 3.6 3.8 3.6 

Western States (Montana, Wyoming, Idaho, Utah, and Si02 ...... .. 6.6 2.9 9.3 5.0 8.6 

California) ................................................................................ . 4.9 AhOs .... .. 1.5 .5 1.3 .9 2.2 

Total ..................................................................................... . 37.

6 Fe20s ..... . .9 .6 1.2 1.0 3.0 

MAJOR USES 

Chemical or thermal processes in which fluorine is liberated; total 67 percent 

Phosphoric acid (wet process) .......................................................... 10.1 

Electric furnace phosphorus............................................................. 6.8 

Triple superphosphate .................................... ................................. 3.8 

Ordinary superphosphate................................................................. 4.5 

Uses in which no fluorine is liberated; total 33 percent 

Exports .............................................................................................. 10.9 

All others........................................................................................... 1.5 

Fluorine is liberated during acidulation and electric 

furnace reduction of phosphate rock as a mixture of polymeric forms of hydrogen fluoride, which attack silica and 

are released as silicon tetrafluoride gas (Siems, 1951). 

About two-thirds of the total production of phosphate 

rock currently is treated chemically or thermally to 

produce superphosphate and a gaseous effluent that 

contains fluorine. In 1970, the 25 million tons of 

1Average Phosphoria Formation whole-rock analysis (Gulbrandsen, 1966, table I). 2Average of three samples of concentrate. Analyses by U.S. Geological Survey. 

!Average of 40 samples of concentrate. Analyses by phosphate companies and U.S. Geological Survey. 

•Average of 20 samples of +I mm material. Analyses by U.S. Geological Survey. 5Average of 20 samples of concentrate ("'I mm+O.l mm). Analyses by U.S. Geological Survey. 6Average of 6 samples (Jacob and others, 1933, table I). 

The analyses listed are all averages; those from the 

western field and from Tennessee are for total rock; the 

others are for beneficiated material, either flotation concentrate or coarse (pebble) fraction of the land-pebble district of Florida. The average analyses are thought to be representative of the large tonnages shown in the following 

table of reserves. The fluorine content ranges from 3.1 to 

3.8 percent. Individual samples of phosphate rock from 

the western field contain as much as 4.2 percent F 

(Gulbrandsen, 1966), and individual samples of Florida 

concentrate contain as much as 4.3 percent F; the highest 

grade samples of Florida pebble and of North Carolina 

concentrate contain about 3.8 percent F. 

Reserves of phosphate in the United States total about 

10 billion tons as shown in the following table, but these 
PRESENT AND FUTURE RESOURCES OF FLUORINE 83 

figures represent only a fraction of the total resources. For 

example, reserves in Wyoming are listed as 2 billion tons, 

whereas total resources in Wyoming (Sheldon, 1963, table 

20) are about 19 billion tons, and the total resources of 

phosphate in North Carolina are estimated to be about 10 

billion tons. Not all the total resources are minable, and 

the chemical composition of the material is not well 

known, but it is certain that the additional resources will 

contain lower percentages of P20 5 and fluorine than the 

reserves shown. 

Phosphate reserves, United States, in millions of long tons 

Map No. 

(Fig. ll) Reserves References 

Eastern United States 

1. Florida, land-pebble............ 1,000 

2. Northern Florida-southern 150 

Georgia. 

3. Northern Georgia-southern 800 

South Carolina. 

5. North Carolina .................... 2,000 

6. Tennessee............................. 80 

Total......................... 4,030 

McKelvey and others (1953). 

Sever, Cathcart, and Patterson 

(1967); Olson (1966). 

Furlow (1969); Heron and 

Johnson (1966). 

U.S. Geol. Survey (unpub. 

data). 

Jacob (1953). 

Western United States 

(Includes reserves above entry level and within 100 feet (30 m) below entry level that 

contain more than 24 percent P20 5• Preliminary figures.) 

7. Idaho.................................. 2, 700 W. C. Gere (written commun., 

1972). 

8. Wyoming........................... 2,000 Do. 

9. Utah................................... 900 Do. 

10. Montana............................. 400 Do. 

Total ....................... 6,000 

PRESENT AND FUTURE RESOURCES OF 

FLUORINE 

By D. R. SHAWE, R. G. WoRL, R. E. VAN ALSTINE, 

and A. V. HEYL 

Present and future resources of fluorine in the United 

States will be examined largely in the light of past exploitation. Until recently fluorspar was virtually the only 

source of fluorine, and probably will remain the major 

source in the near future. A relatively minor amount of the 

fluorine consumed is presently being recovered from processing phosphate rock, and an insignificant amount has 

been acquired in the past from topaz deposits. Phosphate 

rock and other byproduct and coproduct sources of 

fluorine will become increasingly important in the future. 

Byproduct recovery from fluorspar mining throughout 

the United States in the past has not been extensive; sulfide concentrates containing mainly lead, zinc, and silver 

are recovered in some fluorspar operations, and in a few 

barite is a coproduct. 

During the period 1900-70 the United States has 

changed from the major world producer of fluorspar to 

about seventh or eighth rank, although its production has 

generally risen. According to Worl, Van Alstine, and 

Shawe (1973, fig. 1), during 1900-20annualfluorsparproduction grew from about 18,500 short tons to an average of 

about 200,000 short tons of CaF2; during 1920-40 it 

averaged somewhat more than 100,000 short tons; and 

during 1940-70 average annual production increased from 

about 300,000 short tons to a maximum of more than 

400,000 tons during World War II, and then decreased to 

about 200,000 tons. Until about 1950 United States production of fluorspar nearly equalled its consumption, but 

since 1950 consumption has increased dramatically (to 

about 1,500,000 short tons CaF2 in 1970) and so domestic 

production now supplies less than a quarter of the needed 

fluorspar, and imports have been required for the balance. 

Furthermore, since 1950 worldwide fluorspar consumption has increased spectacularly to more than 4,500,000 

short tons CaF2 , emphasizing the fact that the United 

States faces strong competition for foreign supplies of 

fluorspar. 

SUMMARY OF FLUORINE RESOURCES 

By R. E. VAN ALSTINE and R. G. WoRL 

World reserves of fluorspar appear to be adequate to 

meet fluorine requirements in the foreseeable future. 

Similarly, United States reserves of fluorspar appear to be 

adequate for domestic needs for the foreseeable future. 

Worl, Van Alstine, and Shawe (1973, table 1) have estimated that present world fluorspar reserves outside the 

United States are about 165,000,000 short tons of crude ore 

and United States reserves are about 25,000,000 short tons 

of crude ore (crude ore containing more than 35 percent 

CaF2). Hypothetical fluorspar resources (defined as fluorspar that is undiscovered in known districts, or is exploitable only under more favorable economic or technologic 

conditions-the latter termed "conditional" resources by 

Brobst and Pratt, 1973, p. 4) have been estimated as almost 

530,000,000 short tons in the world outside the United 

States and as about 45,000,000 short tons in the United 

States (Worland others, 1973, table 1). Note that the ratio 

of identified reserves to hypothetical resources is about 1:2 

for the United States whereas it is about 1:3 for foreign 

deposits, reflecting the fact that United States resources 

generally have been more extensively explored and 

exploited than have foreign resources. 

Since 1927 several estimates of the fluorspar reserves of 

the United States have been made by government geologists and mining engineers, and each successive estimate 

except the 1968 estimate has been a larger figure. In 1927 a 

reserve of about 5 million tons was estimated for the 

Illinois-Kentucky district (Iron Age, 1927). In 1937 (Burchard, 1937) this figure was increased to 6 million tons 

because of the discovery of more replacement deposits in 

the Cave in Rock area of Illinois (Currier, 1937), and by 1 

million tons for western deposits (Burchard, 1933 ). A joint 

estimate in 194 7 of the U.S. Geological Survey and U.S. 

Bureau of Mines (Davis and others, 1947) showed 14.7 

million tons of fluorspar; a 1952. estimate (Paley, 1952) 
84 GEOLOGY AND RESOURCES OF FLUORINE 

gave the reserve at 15 million tons. A more detailed estimate by Van Alstine (U.S. Geol. Survey, 1956) of about 250 

fluorspar deposits in the United States showed about 22~ 

million tons (see the following table); 50 deposits contained 77 percent of the ore reserves. A similar estimate of 

21 million tons was made by a geologist in private industry 

(Sutton, 1954). 

Estimated reserves of higher grade fluorspar in the United States as 

of October 1956, by regions, in terms of short tons of crude ore 

[Higher grade fluorspar contains at least 35 percent CaF2 or equivalent] 

Location Measured and Inferred Total Approximate 

indicated percent 

Illinois, Kentucky .. 8,100,000 4,000,000 12,100,000 54 

Colorado, Idaho, 

Montana, Utah, 

Wyoming ............ 4,500,000 3,700,000 8,200,000 36 

New Mexico, 

Arizona, Texas .... 800,000 700,000 1,500,000 7 

California, Nevada, 

Washington ........ 400,000 350,000 750,000 3 

New Hampshire, 

Tennessee, 

Alaska ................. 10,000 10,000 

Total.. .......... 13,800,000 8,760,000 22,560,000 100 

In 1968 Van Alstine (U.S. Geol. Survey, 1968) estimated 

that fluorspar reserves were decreased to about 10 million 

tons because about 8 million tons of crude ore had been 

mined, new ore had been discovered, and about 7.5 million 

tons was transferred to the potential resource category. 

This quantity was no longer regarded as ore because it 

became more profitable to use cheaper imports of fluorspar from Mexico, Italy, and Spain than to mine from 

many of our domestic deposits. 

The current estimate of 25,000,000 tons takes into 

account the improved market situation as well as new 

fluorspar discoveries (Worl and others, 1973, p. 230). 

Nearly all these reserves are believed amenable to beneficiation into acid-grade and metallurgical-grade concentrates. Even ores in which fluorite is intimately intergrown 

with gangue minerals might be made into concentrates 

acceptable to the steel industry with the use of sink-float 

methods, blending of ores or concentrates, and the 

sintering, nodulizing, or pelletizing of material that meets 

the chemical specifications of metallurgical-grade fluorspar. In recent years increased use of heavy-media preconcentrators, the pelletizing of flotation concentrates into 

metallurgical-grade fluorspar, and cost-cutting mining 

practices have permitted the working of lower grade ores, 

even though salary scales and material costs have 

mounted. However, the price of fluorspar has increased 

above previous prices so that in 1972 all grades averaged 

about $70/ton. 

Deposits included in the estimate range in size from less 

than 10,000 tons to at least 500,000 tons. Replacement 

bodies of fluorspar in the Cave in Rock area, Illinois, 

average about 9 feet (3m) in thickness and about 125 feet 

(38 m) in width. Dimensions of typical veins in New 

Mexico are given by Rothrock and others (1946, p. 21). 

Potential resources of fluorspar in the United States 

total about 45 million tons of material containing 15-35 

percent CaF2• Such resources, located chiefly in Illinois, 

Kentucky, Colorado, Montana, Nevada, New Mexico, 

Utah, Idaho, Texas, and Alaska, are incompletely known 

because few marginal or submarginal fluorspar deposits 

have been explored. A substantial addition to our potential resources resulted from the recent (The Northern 

Miner, Toronto, Feb. 18, 1971) estimates for the Lost River 

area, Alaska, where about 10 million tons of material contain 28.5 percent CaF2 and 0.2 percent Be; 5.3 million tons 

of this material also contain 0.42 percent Sn and 0.1 percent W03 (Sainsbury, 1964b; 1969). 

Sedimentary phosphate rock which contains 3-4 percent F constitutes a largely untapped fluorine resource; 

fluorine has been recovered from phosphate rock only in 

recent years and it does not yet constitute an appreciable 

fraction of the market. On the basis of a fluorine content of 

about 3 percent in marine phosphate rock, the phosphate 

deposits of Florida, North Carolina, South Carolina, 

Tennessee, Alabama, Utah, Wyoming, Idaho, and Montana contain about 1/ 3 billion tons of fluorine in known 

reserves and about 2 billion tons of fluorine in identified 

resources. This indicates that marine phosphate rock constitutes by far the United States' and the world's largest 

fluorine resource. 

Phosphate rock soon could become an important source 

of artificial fluorite, artificial cryolite, fluorine, or fluorine 

chemicals; two new fluosilicic acid recovery units were put 

into operation in recent years (Everhart, 1963) by phosphate producers in Florida to supply raw material to a new 

fluorine chemical plant in the area. Aluminum Company 

of America has announced (American Metal Market, 1969) 

construction of a new plant in central Florida to make 

aluminum fluoride and cryolite from fluosilicic acid from 

phosphate rock. The production of fluosilicic acid and 

sodium fluosilicate from phosphate rock for water fluoridation is increasing, especially with greater efforts to 

reduce air pollution around phosphate plants. 

Topaz, found relatively rarely in large concentrations, 

occurs in probable commercial quantity and grade in at 

least two localities in the United States. Reserves at the 

Brewer gold mine in South Carolina were estimated at 

about 100,000 tons of schist averaging approximately 15 

percent topaz and about 1,200 tons of topaz in adjacent 

placer deposits that contain 1-24 percent topaz. The hypothetical resources at this deposit are estimated at about 

800,000 tons of topaz rock. In the Front Range, Colo., a 

lens in Precambrian gneiss containing about 15 percent 

topaz was estimated to constitute a reserve of about 600,000 

tons of topaz-bearing rock. The hypothetical resources of 

this topaz-bearing rock are estimated to be about 250,000 

tons for every 100 feet (30 m) of depth. 

Topaz also occurs in significant amounts (along with 

fluorite) in the major molybdenum porphyry deposits at 
PRESENT AND FUTURE RESOURCES OF FLUORINE 85 

Climax and Henderson, Colo., and Questa, N. Mex. 

Reserves of fluorine at these deposits have not been 

estimated but byproduct resources in molybdenum porphry deposits may constitute as much as several million 

tons of fluorine. 

Bastnaesite in carbonatite at Mountain Pass, Calif., contains a potential fluorine resource. This rare-earth mineral 

constitutes 5-15 percent of the carbonatite rock and contains a bout 7 percent fluorine. Based on an estimate of 100 

million tons of potential ore resources at Mountain Pass 

(Olson and others, 1954), nearly 1,000,000 tons of fluorine 

exists as a potential byproduct of rare-earth extraction. 

KNOWN FAVORABLE AREAS FOR FLUORINE 

EXPLORATION 

By D. R. SHAWE, R. E. VAN ALSTINE, R. G. WoRL, and A. V. HEYL 

Search for fluorspar naturally should first be made close 

to areas where the mineral already has been found. In the 

productive districts extensions of known fluorspar bodies 

should be explored along strike and in depth. Additional 

ore bodies may be found along nearby faults in mineralized districts. Search should be directed especially for 

stratiform deposits in limestone which have been susceptible to replacement by fluorite; these deposits tend to 

be large and amenabJe to large-scale low-cost mining 

operations, and in the important southern Illinoiswestern Kentucky district sizable areas having economic 

potential have not yet been adequately explored. 

Geochemical investigation of fluorine and related metal 

anomalies may reveal commercial deposits. Disseminated, 

lower grade deposits marginal to known bodies may be 

profitable; some drab, fine-grained, earthy material is 

difficult to recognize visually as fluorite. An increasingly 

important source of fluorspar will be as a coproduct from 

the mining of iron, base-metal, barite, and rare-earth ores. 

As in Mexico, £I uori te may be recovered also from mine 

dumps and tailings ponds, where it is already ground and 

partly concentrated. More fluorine analyses should be 

made routinely on earth materials; thus a new 

environment for fluorspar may be discovered, as recently 

described in Tertiary tuffaceous lake beds of Oregon 

(Sheppard and Gude, 1969). 

Most fluorspar districts and localities in the United 

States remain as areas favorable for further exploration for 

fluorine resources. The recent discovery of large fluorspar 

reserves in the Lost River tin district, Alaska, suggests that 

similar geologic settings along the Rapid River thrust 

fault elsewhere in the York Mountains are favorable for 

the occurrence of such carbonate-replacement and pipelike fluorspar deposits. Other tin districts on the Seward 

Peninsula, fluorite-mineralized carbonate rocks north of 

Nome, breccia pipes in the Kigluaik Mountains, and 

carbonate rocks surrounding alkalic rocks in the Darby 

Mountains, all offer potential for undiscovered fluorspar 

deposits. Elsewhere in Alaska, areas where peralkalic 

granites are known or where fluorite and topaz are 

associated with sulfides are favorable for fluorine mineral 

concentrations. Large fluorine resources are available 

although currently inaccessible in phosphate rock in 

northern Alaska. 

In the northwestern part of the United States important 

fluorspar deposits that may have additional potential are 

the Challis, Big Squaw Creek, and Meyers Cove deposits, 

Idaho, where fluorite veins occur in dolomite, biotite 

gneiss, and volcanics and porphyries, respectively; and the 

Snowbird and Crystal Mountain deposits, Montana, 

which are pegmatitelike bodies. Numerous other fluorspar deposits associated with volcanic rocks, granitic 

intrusive rocks, and alkalic rocks, and occurring as pegmatites and disseminated in granite are widespread in the 

Northwest, specifically in north-central Washington, central and southwestern Idaho, western to central Montana, 

several areas in Wyoming, and the Black Hills of South 

Dakota, and the areas of these deposits may be favorable 

for further exploration for fluorspar resources. 

The States of Idaho, Montana, Wyoming, and Utah 

contain extensive fluorine-bearing phosphate rock; as the 

distribution of these deposits is well known, large 

unknown resources of fluorine in phosphate rock are not 

likely in this region. 

In the southwestern part of the United States substantial fluorspar potential is likely in the vicinity of major 

known districts as well as around districts of only minor 

production. Additional replacement bodies in limestone 

in the Fluorine district, Nevada, vein deposits in andesite 

and rhyolite at Broken Hills, Nev., pipe deposits in carbonate rocks at Spor Mountain, Utah, and veins in volcanic 

rocks in the Indian Peak Range, Utah may still be found. 

Throughout much of Nevada, southeastern California, 

western Utah, and western Arizona numerous minor 

occurrences of fluorspar in veins, mantos, and pipes in and 

associated with volcanic rocks, in contact zones and stockworks of hypabyssal and plutonic igneous rocks, in volcaniclastic sediments, and in pegmatites, mark possible 

targets for exploration for additional fluorspar resources. 

Of the localities having had only minor fluorspar production, perhaps the most promising are the Quinn 

Canyon Range, Nev., and the Castle Dome district, 

Arizona. 

The southern Rocky Mountain region of the Western 

United States in Colorado, New Mexico, western Texas, 

and southeastern Arizona offers numerous favorable areas 

where additional fluorspar resources may be discovered in 

the vicinity of known districts and deposits. Among the 

deposits characterized as layered and crustified veins in 

young steep tensional faults and breccia zones occurring 

in Tertiary volcanic rocks, Paleozoic and Mesozoic sedimentary rocks, and Precambrian silicic igneous and metamorphic rocks are the Northgate and Browns Canyon 

districts, and deposits at Crystal, Poncha Springs, and 

Wagon Wheel Gap, Colo., and the Gila, Burro Moun-
86 GEOLOGY AND RESOURCES OF FLUORINE 

tains, Anderson, Gold Hills, Steeple Rock, Sierra 

Caballos, Zuni Mountains, Fluorite Ridge, and Cooks 

Peak districts, and deposits at Tonuco, Tortugas 

Mountain, Bishop Cap, and Sierra Cuchillo, N.Mex. The 

Sierra Caballos, Sierra Cuchillo, and Tortugas and Bishop 

Cap deposits in New Mexico and the Eagle Mountains and 

Christmas Mountains-Corazones Peak districts in Texas 

also offer potential for manto-type deposits. Significant 

stockworks, pipelike shoots, and mineralized breccia zones 

near a middle Tertiary alkalic-silicic stock and containing fluorite, lead, silver, gold, copper, and uranium 

minerals may still be found in the Jamestown district, 

Colorado. Other minor occurrences in the Southern 

Rocky Mountain region also may mark favorable targets 

for significant undiscovered fluorspar deposits. 

Numerous favorable structures in the Illinois-Kentucky 

district should be explored further for fluorspar. A very 

large potential for undiscovered deposits still exists in the 

district. Large low-grade tonnages of fluorspar-mineralized breccia are known near Hicks dome but have not yet 

been developed. 

· Elsewhere in the Central and Eastern United States a 

large potential also exists for the discovery of new fluorine 

resources in the vicinity of known districts and deposits. 

All districts and deposits warrant further evaluation for 

additional resources, but only those with the most promise are mentioned here. The Central Tennessee district 

may have the largest fluorspar potential in the United 

States outside of the Illinois-Kentucky district. Breccia 

fluorspar deposits are known at depth in the Central Tennessee district, and similar deposits may occur in quantity in Ordovician carbonate strata in the Cumberland 

River vein district in Kentucky. The Central Kentucky 

district offers good possibilities for undiscovered fluorspar-bearing bedded and breccia deposits and veins. 

Fluorspar-bearing veins in or near the Rossie district, 

New York, promise additional potential. The Sweetwater 

district of eastern Tennessee and similar zinc-barite districts with fluorite throughout the Appalachian Valley 

and Ridge province between Alabama and Pennsylvania 

offer fluorspar potential. Districts where fluorite occurs 

with quartz and in mineralogically more complex veins 

are known in the Blue Ridge, Piedmont, and New Jersey 

Highland provinces from Alabama to southern New York 

and in New England. The most favorable for exploration 

are the Del Rio district, Tennessee, and the Hot Springs 

district, North Carolina. Ordovician carbonate rocks in 

the subsurface in the vicinity of the alkalic intrusive center at Magnet Cove, Ark., may have potential for fluorspar 

deposits. 

Careful geologic mapping where fluorine minerals are 

known but where adequate geologic maps are not now 

available will be essential to the development of additional fluorine resources in many areas, for example, as 

demonstrated at Lost River, Alaska. 

SUGGESTIONS FOR LIKELY FUTURE 

FLUORINE PROVINCES: SPECULATIVE 

FLUORINE RESOURCES 

By D. R. SHAWE, R. G. WoRL, and A. V. HEYL 

Exploration for and evaluation of speculative fluorine 

resources-those occurring in districts and environments 

that are yet to be identified-must be based on knowledge 

of the geologic environment and the geochemical cycle of 

fluorine. Geologic mapping in areas not now adequately 

covered by geologic maps will be essential to evaluation of 

geologic environment and to successful exploration in 

such areas. Major geologic parameters that partly define 

the geologic environment of fluorine mineral deposits are: 

(I) extensional tectonism related to deepseated northwesterly and northeasterly conjugate strike-slip structures; (2) high heat flow from the mantle; and (3) magmatism of alkalic affinity characterized by abundant fluorine. 

Regions of extensional tectonism are clearly the locales 

of fluorine mineral deposition in the recent geologic past 

and presumably have been in older geologic periods. 

Fluorine deposits of middle Tertiary and younger age are 

widespread in regions of rift and block faulting also of the 

same age, and in fact numerous fluorine deposits occur in 

tension faults in these provinces. Tension fractures in 

regions of extension appear to be a phenomenon of the 

upper part of the crust, but no geologic evidence suggests 

that most of the fluorine itself was derived from the upper 

part of the crust to be concentrated into tension fractures. 

Furthermore, the patterns of distribu~ion of fluorine 

mineral deposits within tensional provinces, that is, the 

tendency for deposits to form northwesterly and northeasterly alinements, reflects the similar alinement of 

deeper-seated regional fracture zones of strike-slip 

character that probably penetrate downward through the 

crust and constitute the basic structural framework of 

regions of tension. The general distribution of fluorine 

mineral belts in extensional provinces thus suggests 

derivation of fluorine from deep within the crust or from 

the upper mantle. 

Broad regions of high heat flow in the United States 

coincide with regions of extensional tectonism that is now 

going on or has occurred in the recent geologic past. Such 

regions in the Western United States are further distinguished by low seismic velocity in the upper mantle, 

suggesting abnormally high temperature in the upper 

mantle that in turn accounts for the high heat flow in the 

overlying crust. Of course such regions are also characterized by abundant hydrothermal activity, including 

present-day hot springs. Low seismic velocity in the upper 

mantle also may indicate a phase change from dunitic to 

eclogitic composition, implying chemical transfer 

between mantle and crust, perhaps fractionation of mobile 

components from the mantle into the crust. Regions of 

high heat flow thus provide two significant factors 

essential to the formation of fluorine mineral deposits: an 
PRESENT AND FUTURE RESOURCES OF FLUORINE 87 

original source of fluorine (from the upper mantle), and 

the energy necessary to mobilize fluorine into upper levels 

o.f the crust. 

The distribution of fluorine-rich igneous rocks of 

alkalic affinity in the Western United States coincides with 

regions of extensional tectonism and high heat flow. 

Again, the ages of the igneous rocks generally coincide 

with the periods of tectonism and of inferred correlative 

high heat flow. The foregoing generalization needs 

elaboration, however, in order to account for the occurrence and distribution of alkalic rocks of different ages and 

petrologic character with which fluorine mineral deposits 

are associated. According to one model, during early to 

middle Tertiary time in the Western United States 

imbricate subduction took place as a result of differential 

crustal plate movements, such that an eastward-dipping 

oceanic plate underrode the continent in two northtrending zones parallel to the continental margin, one 

underlying the western segment of the Cordillera and the 

second underlying the present Rocky Mountain trend. In 

each zone potassium content of the andesitic igneous rocks 

that were generated by subduction increases eastward 

(Lipman and others, 1972). Rocks formed along the 

eastern edge of the Rocky Mountain zone are typically of 

alkalic character-including trachytes, trachybasalts, 

phonolites, and other alkalic types-suggesting that their 

derivation from the subduction zone was at greater depth 

and under stronger influence of mantle conditions than 

was the derivation of calc-alkalic types of similar age. Our 

colleague T. A. Steven suggested orally to us that derivation from a mantle environment also accounted for the 

higher fluorine content of these rocks and the association 

with them of fluorine mineral deposits. 

In middle Tertiary time extensional tectonism was initiated in the Western United States, marked by a cessation 

of subduction in the regions of extension ·(Lipman and 

others, 1972). Onset of extensional tectonism in the 

Western United States was marked by transition from 

andesitic to fundamentally basaltic or basaltic-rhyolitic 

volcanism (Christiansen and Lipman, 1972). The cause of 

the generation of fluorine enriched magmas of alkali 

rhyolite and associated basaltic types during the episode 

of extension is problematical. We infer it to be likely that 

such magmas originated in the upper mantle, probably as 

molten fractions of components with high vapor pressure, 

that were transported upward into the lower-pressure environment of the crust. According to our belief, distention 

of the continental lithospheric plate due to differential 

plate motion resulted in at least incipient dilatant zones in 

the crust and in the underlying mantle, such that fluorineenriched magma and fluids moved into" the crust from the 

mantle, and the system of northwesterly and northeasterly 

strike-slip faults in the crust which implemented the distention and accounted for the block faulting in the upper 

part of the crust allowed passage of magmas and fluids 

from the mantle farther upward through the crust. The 

suggestion that change in state within the upper mantle 

resulted from dilatancy due to differential plate motion, 

rather than the converse, was also proposed by 

Christiansen and Lipman (1972, p. 276). 

Thus we see that although fluorine-enriched magmas 

are spatially associated with regions of extensional 

tectonism they are in minor part older than the episode of 

extension and related to other processes. We believe the 

significant fact of their origin is that it was influenced by 

mantle processes, and the material of the magmas was 

derived from the mantle. 

The generalizations above, drawn on the relations 

observed in the Western United States, can be extrapolated to other regions. We propose, for example, that 

fluorine-enriched magmas of late Paleozoic age in the 

Eastern United States were derived from the lower zones of 

subduction-and hence strongly influenced by the 

mantle-in a tectonic belt that then bordered the eastern 

edge of the continent. These magmas were responsible for 

formation of some but not all of the fluorine mineral 

deposits in the Appalachian belt of the Eastern United 

States. Also probably in late Paleozoic time deeppenetrating strike-slip faulting along the 38th parallel of 

latitude in the Eastern United States (Heyl, 1972) allowed 

mantle-derived magmas and fluids to move upward into 

the upper part of the crust in the area of southern Illinois 

and western Kentucky to account for the extensive 

development of fluorine mineral deposits there. In Africa, 

the notable restriction of halogen-rich igneous rocks and 

fluorine mineral deposits to the rift-valley zones reflects 

the deep penetration by those structures. 

Fluorine apparently is very mobile in the geologic environments described in preceding paragraphs. Fluorinebearing solutions genetically related to the major geologic parameters specified have permeated country rock, 

such as altered and mineralized volcaniclastic sediments of 

the Western United States; have filled fractures in and 

replaced receptive country rock, as in the IllinoisKentucky district; and have filled subsidiary fractures in 

places some distance from igneous activity and major 

structures, as in many fluorspar districts of the Western 

United States. Fluorine also moved into other geologic environments associated in time and space with the major 

geologic parameters to form deposits in the other environments. To use an example from another continent, 

fluorine mobilized by exhalations or weathering has been 

transferred from alkalic igneous rocks and carbonatites 

along African rift structures into lake brines, to be concentrated in evaporites of the rift valleys. Formation of the 

marine sedimentary carbonate fluoraptite deposits is an 

important example of reconcentration of fluorine in the 

supergene cycle. 

Older concentrations of fluorine minerals may be reworked virtually in place by younger processes that tend to 
88 GEOLOGY AND RESOURCES OF FLUORINE 

mobilize fluorine. In such cases it is impossible to tell on 

the basis of current knowledge whether younger deposits 

associated with older deposits consist entirely of 

"primary" introduced fluorine, or entirely of remobilized 

older fluorine, or a combination of these. One example is 

fluorite in the Tertiary gold ores of Cripple Creek, Colo., 

that are associated with fluorine-rich phonolites and 

related rocks of Tertiary age (Lindgren and Ransome, 

1906, p. 122, 219, 100) and also occur within fluorine-rich · 

Pikes Peak Granite of Precambrian age. Another is 

fluorite in faults of post-Precambrian age at Mountain 

Pass, Calif., that are associated with dikes of Tertiary age 

and also are close to bastnaesite-bearing carbonatite of 

Precambrian age. These occurrences recall the point 

emphasized by Peters (1958, p. 667, 683-684) of recurrent 

mobilization of fluorine from older deposits in fluorinerich regions. 

The major geologic parameters previously discussed define environments and processes in which fluorine was 

intrinsically available in abnormal amounts in some part 

of the system, and could be mobilized into concentrations 

of economic interest. On the other hand, geologic 

processes in other environments also have acted to concentrate minor (crustal abundance) amounts of fluorine into 

deposits of economic interest, for example, the precipitation of fluorapatite from seawater. 

The geochemical cycle of fluorine can be summarized to 

show that the inferences are valid regarding the geologic 

environments in which fluorine is concentrated. Despite 

the fact that fluorine-rich alkalic rocks appear to be 

derived from the mantle, and perhaps from deeper in the 

mantle than its top, rocks irrupted through oceanic crust 

and clearly derived from the mantle are low in fluorine. In 

the oceanic environment only magmas that have differentiated in near-surface chambers have tendencies toward 

alkalic affinities and fluorine enrich~ent. In the 

continental environment, however, some fluorine-rich 

magmas likely were derived from the mantle by a process 

that resulted in fluorine enrichment, or were differentiated in higher crustal levels to account for fluorine enrichment; some fluorine-rich magmas may have been 

generated within the crust in a local fluorine-enriched environment, but we do not believe that this was a dominant 

process, and it probably occurred in a sporadic fashion. 

The tendency for nigh mobility of fluorine within the 

crust is exhibited by the occurrence of fluorine mineral 

halos around fluorine-rich intrusives, by the fact that extrusive rocks tend to contain less fluorine than do intrusive rocks, showing a loss of fluorine under lower pressure 

conditions, and by the fact that volatile components 

emitted by volcanoes formed from fluorine-rich magmas 

include substantial fluorine. Geochemical data also show 

that crystallization of magma tends to drive off fluorine if 

minerals that can take up fluorine are not formed. 

Weathering of rocks at the earth's surface transfers large 

amounts of fluorine into surface and ground waters; some 

of this may be reconcentrated in the near-surface environment, such as in lake brines, but much is transported to the 

oceans where it is redeposited in sedimentary rocks that 

generally contain amounts of fluorine comparable to 

those of igneous rocks. Under special conditions in the 

oceans large amounts of fluorine become concentrated in 

sedimentary phosphate deposits, yet these amounts are 

still only a small percentage of the total fluorine deposited 

in marine sediments having lower fluorine content. 

Metamorphism of sedimentary rocks may cause segregation of fluorine, but evidence of this process is fragmentary. In this respect, Cannon and Pierce (1967) stated that 

most stratiform lead-zinc-barite-fluorite deposits "in the 

central lowland of North America contain J-lead of 

variable isotopic composition, part or all of which 

originated by mobilization of rock-lead from the Precambrian basement or enclosing marine sedimentary rocks." 

Whether the source of the fluorine in these deposits is the 

same as that of the lead is a moot point. Ultrametamorphism of sedimentary and other rocks having concentrations of fluorine may result in development of fluorinerich magmas and associated fluorine mineral deposits, but 

again more evidence is needed to prove that such a process 

has occurred. Negative fluorine-silica correlations in some 

igneous suites suggest this mechanism as they indicate 

formation of the igneous rocks by other than magmatic 

differentiation. 

The principles discussed in preceding pages assure us 

that numerous possibilities exist for new fluorine 

resources. At present it is impossible to give a quantitative 

indication of speculative resources other than that they are 

probably very large. 

Generally, prospecting for fluorine mineral deposits in 

regions of relatively young tectonism and magmatism 

should have greatest success where regional northwesterly and northeasterly strike-slip structural zones have 

been intruded by fluorine-rich magmas, or are underlain 

by large volumes of alkalic volcanic rocks. In regions 

where older tectonism and magmatism have been 

obscured by younger geologic events these major geologic 

features should still be sought. Of course, other deeply 

penetrating structural zones, particularly major east-west 

fault zones, where fluorine-rich mantle-derived magmas 

have been irrupted, also should be favorable locales for 

fluorine mineral deposits. 

In the United States new fluorspar districts may be 

found northwest of the important Illinois-Kentucky district in carbonate rocks beneath Pennsylvanian rocks, and 

also northeast of this district toward Ohio and the Michigan basin, beneath Pleistocene cover where fluorite occurrences are known in Silurian and Devonian dolomites. 

Northern Ohio in the vicinity of Toledo, the Serpent 

Mound cryptoexplosion structure in southeastern Ohio, 

southern Indiana west of Louisville, Ky., and the Ste. 

Genevieve fault zone of southeast Missouri and southern 

Illinois, may all contain undiscovered fluorspar deposits. 
GEOCHEMICAL AND GEOPHYSICAL PROSPECTING METHODS 89 

Similarly, the Paleozoic carbonate rocks of central 

Tennessee and central Kentucky are widely mineralized 

with fluorite, as shown in recent drilling, and may contain other commercial deposits. Carbonate rocks in subsurface in the vicinity of alkalic intrusives, at Magnet 

Cove, Ark., may have potential for new fluorspar districts. 

Large but lower grade stratiform fluorspar deposits in 

carbonate rocks, like those worked in the United States, 

Frarice, USSR, and southern Africa, probably will be 

popular targets for exploration in the United States. 

In the Western United States fluorspar deposits undoubtedly underlie parts of the widespread cover of Tertiary and Quaternary sediments and volcanic rocks. 

Cenozoic calcareous tuffaceous lake beds in the Western 

United States may be fluorite-bearing, similar to those 

known in Oregon, Italy, and southern Africa, some of 

which are of commercial interest. These and other occurrences of this type of fine-grained fluorite may offer potential for large fluorine resources. Some fluorspar 

deposits of the Western United States are related 

genetically to areas of silicic-alkalic volcanic rocks, 

namely the Big Bend igneous subprovince of Texas; the 

Nacimiento igneous subprovince of Arizona, New 

Mexico, and Colorado; and the Shoshone igneous 

province of Nevada, Utah, Idaho, and Montana. Other 

areas with relatively high fluorine contents in the volcanic rocks might merit further prospecting, especially 

southeastern Idaho, northwestern Wyoming, and northwestern Utah. In the Thomas Range of west-central Utah, 

topaz is disseminated in volcanic rocks and commercial 

fluorspar deposits are distributed around the western 

periphery of a caldera. Only a third of the caldera is 

exposed; the remainder, which is covered by rhyolite flows 

or alluvium, may contain undiscovered deposits (Shawe, 

1972, p. B76-B77). A tectonic unit consisting of the Rio 

Grande trough in New Mexico and its northern extension 

through Colorado is especially rich in fluorspar deposits 

and should be explored further. Deposits of syngenetic 

fluorite associated with gypsum and limestone are 

reported from Permian marine evaporites in the Bighorn 

Basin, Wyo. These resemble extensive deposits known in 

the Permian of USSR; similar evaporites elsewhere in the 

United States should be investigated for fluorite deposits. 

Chao and others (1961) reported a new fluorine mineral, 

neighborite (NaMgF3), from the Green River Formation, 

Utah; the economic potential of this mineral here and elsewhere is unknown. 

Large deposits of fluorapatite in marine phosphate rock 

probably exist beneath the sea in Tertiary (and younger?) 

coastal plain sediments extending east from phosphate 

deposits in the Carolinas and Florida. Although fluorine 

is recovered from huge deposits of fluorapatite in alkalic 

rocks of the USSR, the possibility is not great that deposits 

of this type may be found and profitably explored in the 

United States. 

Probably millions of tons of topaz-bearing rock are yet 

to be discovered in widespread metamorphic terranes 

throughout the United States as well as in still-unknown 

molybdenum-bearing porphyry deposits. Because cryolite is a rare mineral, it may not be an important source of 

fluorine; the world's only known commercial deposit of 

natural cryolite, in Greenland, has been depleted, but 

similar deposits elsewhere are conceivable. Sodium 

fluoride has been found in saline lake beds in Tanganyika; it may be present in similar rocks in the ~nited States 

and may some day be a source of fluorine. 

Some brines, volcanic gases, fumaroles, and hot springs 

with relatively high fluorine contents may suggest 

fluorine-rich provinces in which deposits of fluorspar, 

phosphate rock, or other fluorine materials should be 

sought. Deep-sea sediments, which have more fluorine 

than most other marine sediments except phosphate rock, 

contain about 700 ppm F; these types of sediments and sea 

water itself, which has about 1 ppm F, may be sources of 

fluorine in the distant future. 

Other possible new resources of fluorine, not in thecategory of speculative resources but classified as conditional 

resources, are known small but high-grade deposits, and 

very large probably low-grade multicommodity ores. 

Numerous high-grade but small deposits of fluorspar, 

such as those of the Western and Eastern United States 

might be utilized. To do so would require better techniques than now used of locating and evaluating small 

pods of fluorspar, and it would also require the use of 

portable extraction and processing equipment. Even 

though mining of this type of deposit may be feasible elsewhere in the world it is not likely to be in the United States, 

however, because of high labor costs and land problems. 

Very large low-grade multicommodity ores offer potential fluorine resources. These include deposits in which 

fluorine, mainly in the form of fluorite, is associated with 

metallic minerals and those in which it is associated with 

or contained in other minerals of commercial interest such 

as barite, bastnaesite, fluorapatite, zeolites, and feldspars. 

It may be possible in the future to process such multicommodity ores in which no single commodity is of high 

enough grade to be commercial by itself. 

GEOCHEMICAL AND GEOPHYSICAL 

PROSPECTING METHODS 

FOR FLUORINE 

By W. R. GRIFFITIS and R. E. VAN ALSTINE 

Fluorspar deposits have commonly been found by identification of fluorite in outcrops and surficial materials 

(Grogan, 1960, p. 374; 1964). The surficial materials 

include soils, anthills, spoil piles of burrowing animals, 

landslides, and alluvium. The persistence of fluorite 

during weathering under certain conditions, and the high 

fluorine content of the mineral, suggest that geochemical 

methods might be used in prospecting for fluorspar. 
90 GEOLOGY AND RESOURCES OF FLUORINE 

Nevertheless, geochemistry has not been used much, in 

part because of the lack of rapid analytical precedures that 

could be used to determine the fluorine contents of 

samples with the necessary reliability and low cost. 

Recent work in western North America has shown that 

fluorite deposits may effectively be sought there by heavy 

mineral and geochemical techniques. The mineral persists for long distances during transport in the sediment of 

streams, and can be concentrated therefrom with the gold 

pan. Thus, the fluorite of the Jamestown district, Colorado, can be detected in stream sediment as far downstream as the South Platte River, a distance of about 35 

miles (55 km). In southwestern New Mexico fluorite has 

similarly been traced in the sediment of dry washes for distances of several miles. The softness and excellent cleavage of the mineral thus do not cause rapid destruction of 

the grains during transport, nor does the rather low specific gravity prevent its recovery by panning. The occurrence 

of fluorite in stream and seashore sand was summarized a 

decade ago by Milner (1962, p. 107). 

A systematic heavy-mineral survey near Winston, N. 

Mex., during 1970 by H. V. Alminas and K. C. Watts (oral 

commun., 1971; Alminas and others, 1972) showed that 

fluorite is plentiful in sediment near two major subparallel north-trending faults. Near the intersection of the two 

faults Ira Young of Socorro, N. Mex., had independently 

found a large fluorspar deposit. The fluorite that occurs 

without associated metals or with barite in wash sediments is colorless or pale green, whereas many of the 

fluorite grains found in sediments with anomalous basemetal contents are purple. It may be possible in some areas 

therefore to distinguish accessory fluorite of metal 

deposits from fluorite of higher grade fluorspar deposits. 

Preliminary chemical analyses show that silts of dry 

washes contain most fluorine near known fluorspar 

deposits and where fluorite was panned from the 

sediment. 

Geochemical exploration investigations in the semiarid Browns Canyon district, Colorado, by Van Alstine 

(1965) showed that fluorine is found in abnormal concentrations in residual soil directly above and downslope 

from the principal vein and in alluvium downstream from 

the vein. The highest anomalous values were about 6-20 

times the background value in the soil and 3 times the 

background in the alluvium. Fluorine thus can have 

rather low mobility in soils and alluvium in semiarid 

regions. Van Alstine also pointed out the problems introduced where samples contain abundant biotite and hornblende that increase the background fluorine values-a 

problem which is avoided by the determining of contents 

of fluorite instead of fluorine. 

Neither heavy mineral nor geochemical prospecting 

methods for fluorite have been widely applied in fluorspar districts in humid regions. Sang Kyu Yun and others 

(1970) found geochemical studies of stream sediment and 

soils to be useful in prospecting the H wanggangri region 

of Korea. Nackowski (1957) found that fluorine was technically unsuited as an indicator element for preliminary 

exploration for fluorspar in the Illinois-Kentucky district; evidently the humid climate there is unfavorable for 

fluorine to be highly concentrated in the soil. 

Development of thick or well-zoned soils in humid areas 

is commonly accompanied by removal of fluorine from 

near-surface materials. Hence, soil samples taken at 

shallow depth might show subdued anomalies or no 

anomalies over fluoritic bedrock. Therefore, where soils 

are well developed, samples should be taken as deep as 

possible. Soils now being eroded generally have a low 

fluorine content and may result in stream sediments 

diluted sufficiently to be ineffective indicators of mineralized rocks. The great concentration of elements of interest 

that is provided by heavy-mineral separations may be particularly useful in seeking fluorspar. 

Friedrich and Plliger ( 1971) found that lead, zinc, and 

mercury contents of soils were useful guides in exploring 

for fluorite in Spain and that mercury was useful in the 

Wolsendorf district, Germany. They also found that the 

fluorine content of Black Forest stream water increased by 

factors of 2 to 5, exceptionally even higher, in flowing 

through fluorite districts. The use of pathfinder elements 

instead of fluorine avoids the problems of low-level 

fluorine analysis but is successful only where the pathfinder metal is consistently associated with fluorspar. 

lheson (1970) found fluorine to be widely and uniformly dispersed in the limestone wallrocks of the Derbyshire 

district, England, and suggested that the element might be 

used as a guide to fluorite-galena-barite ore. 

Heavy-mineral methods and geochemistry-using zinc 

as a pathfinder metal-both have been tried in the IllinoisKentucky district, but without completely overcoming the 

problems posed by the cover of loess and the segregation of 

fluorite and sphalerite within separate ore bodies along 

the mineralized faults (Keighin, 1968). 

In the Illinois-Kentucky district silver and antimony are 

concentrated in galena, and cadmium~ gallium, and germanium are in sphalerite (Hall and Hey}, 1968). These elements, as well as elements like mercury or vanadium that 

may have been introduced with the mineralizing solutions, may be clues to fluorspar bodies. In the Northgate 

district, Colorado, Worl (U.S. Geol. Survey, 1970) found 

anomalous molybdenum values as high as 800 ppm 

centered on one fluorspar vein. If a fluorspar contains 

uranium minerals-as in the Thomas Range, Utah 

-scintillation counters or Geiger counters might be 

helpful in prospecting for fluorspar. 

Districtwide studies, intermediate between regional reconnaissance surveys and detailed surveys of individual 

vein zones, are still needed. It is obvious, of course, that 

neither geochemical surveys nor heavy-mineral surveys 

alone can reliably show the presence of economic fluor-
REFERENCES 91 

spar deposits, regardless of the scale or detail of the work. 

Such surveys should be used in conjunction with evaluation of the regional geology and of the known structural 

and stratigraphic controls of mineralization. 

The widespread presence of accessory fluorite in metal 

deposits of several types can result in fluorine anomalies 

that are useful primarily as guides to metal ore. J. H. 

McCarthy and G. B. Gott (oral commun., 1971) observed 

that a fluorine anomaly correlates with the area of highest 

gold values in the Cripple Creek gold district, Colorado. A 

fluorine anomaly extends from the Tertiary rocks into the 

Precambrian granite and metamorphic rocks north and 

south of the caldera and closely follows an aeromagnetic 

high. The fluorine values were mostly between 1,000 and 

2,000 ppm; and a few were greater. 

J. E. Gair (oral commun., 1971) reported that fluorine 

anomalies in stream sediments are associated with quartzfluorite-huebnerite veins in the Hamme tungsten district, 

North Carolina. 

Fluorine forms broad anomalies around tungstenbearing skarn in the Pyrenees, according to CachauHerreillat and Prouhet (1971). These authors therefore 

concluded that fluorine would be a useful pathfinder element in a regional search for additional tungsten districts. Ail introduction of fluorine during skarn mineralization is not universal, however. Darling (1971) found 

that biotite from intrusive rock contains less fluorine near 

tungsten-bearing skarn than at some distance from such 

ore. 

Geochemical investigation (Kesler and others, 1973) of 

fluid inclusions in certain igneous rocks, using a simple 

and economical method of analyzing water-extractable 

fluoride in rock powders, may be a helpful tool in searching for fluorine-bearing rocks possibly genetically associated with fluorspar deposits. The study by Kesler and 

others (1973) of nine Laramide granodiorite intrusive 

complexes in the Greater Antilles and Central America 

shows fluoride values in intrusives mineralized with base 

metals to be higher than values in barren intrusives. 

In summary, the fluorite contents of concentrates 

panned from creek and wash sediments are useful in reconnaissance in hilly areas of the semiarid southwest and 

of humid southern Korea. At some places, as in southwestern New Mexico, a visual examination followed by 

determination of the total heavy metal content of concentrates may distinguish between fluorspar and fluoritic 

base-metal deposits. The fluorine contents of soil overlying and downhill from outcrops of faults can be used to 

determine the presence of fluorite mineralization, as 

demonstrated by Van Alstine and by Sang and associates. 

Bardovskiy and Kolpakov (1961), Bardovskiy (1964), 

and Ingerman (1965) indicated that fluorite-bearing zones 

can be effectively distinguished in boreholes by the 

induced activity method, in which the short-lived isotope 

F20 is activated by neutrons from a polonium-beryllium 

source. Percentage of CaF2 determined from the induced 

activity logs agrees well with that determined by chemical 

analysis (error ± 1-2percent). 

Faults in the Illinois fluorspar district (Hubbert, 1944) 

were studied by the earth-resistivity method. The main 

faults were clearly shown by anomalies; elsewhere the 

causes of observed anomalies were not evident. Many of 

the faults are mineralized with fluorite, but it is impracticable to try to detect minable bodies by direct methods of 

geophysical prospecting. The refraction seismic method 

has been used as an indirect means of exploring for fluorspar in southern Illinois (Johnson, 1957). Faults and dikes 

are detectable by this method but the presence of fluorspar 

is not. Self-potential investigations also have been made 

by the Illinois Geological Survey (Weller and others, 1952, 

p. 36-43). 

Alteration zones surrounding the main fluorspar vein at 

Northgate, Colo., were outlined by induced potential 

methods, but the veins in unaltered rock were not (Worl, 

oral commun., 1972). 

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