Fluorspar Deposits 

Near Meyers Cove 

Lemhi County, Idaho

GEOLOGICAL SURVEY BULLETIN 1015-A

Fluorspar Deposits 

Near Meyers Cove 

Lemhi County, Idaho

By D. C. COX

A CONTRIBUTION TO ECONOMIC GEOLOGY 

GEOLOGICAL SURVEY BULLETIN 1015-A

A study of fluorspar deposits in 

the Gravel Range mining district 

of the Salmon River Mountains

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1954
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

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

Washington 25, D. G. - Price $1.25 (paper cover)
CONTENTS

Fag*

Abstract.__-__---_--____-_._--_________.._____________ 1

Introduction. __ ___________________________________________________ 1

Location and general features..-.._________________________ 1

Previous field work_________________________..__________________ 3

Acknowledgments-_____________________________________________ 3

Geology.. __-_____-_---____-__--______-______-_-.____-_____-_____ 4

Lithology ______ ________________________________________________ 4

Structure.. ________________________________________________ 5

Fluorspar deposits._________________________________________________ 6

History of discovery________________________..________________ 6

Localization________________________________________________ 6

Mineralogy.__________________________________________________ 7

Origin_____________________________________________________ 8

Size and grade.__-_______-_________________.________________ 9

Fluorspar lodes____-_-_______-_____________-_--________-__-___--_ 11

Crystle area.-________________________________________________ 11

Purcell area_________________________________________________ 14

Antimony Lode.__________________________________________________ 18

Literature cited.__________________________________________________ 39

Index._______________________________________ 21

ILLUSTRATIONS

{Plates 1-5 in pocket]

PLATE 1. Geologic map of fluorspar area near Meyers Cove.

2. Geologic map of part of Crystle area.

3. Geologic map of Bear Trap Lead.

4. Geologic map of Big Lead.

5. Map o/ Red Spar Lode.

Page

FIGURE 1. Index map showing location of fluorspar district near Meyers

Cove__________________________ _ ___ 2

TABLES

Page

TABLE 1. Analyses of samples from fluorspar deposits near Meyers Cove_ 9

in

A CONTRIBUTION TO ECONOMIC GEOLOGY

Fluorspar deposits near Meyers Cove, Lemhi County, Idaho

By D. C. Cox

ABSTRACT

The fluorspar deposits near Meyers Cove, Lemhi County, Idaho, are localized 

along three groups of shear zones: one group strikes northeast and dips steeply 

northwestward, another strikes northeast and dips gently northwestward, and 

the third strikes northwest and dips gently southwestward. The country rocks 

are tuffs and flows of the Casto volcanics of Permian (?) age and the Challis 

volcanics of late Oligocene or early Miocene age. The known deposits are in a 

belt about 3 miles long and 2 miles wide and crop out at altitudes between 5,100 

feet and 7,200 feet above sea level.

The principal vein minerals are fluorite, chalcedony, and barite. The fluorite 

occurs as lodes, crusts around fragments of rock, and replacements of fine breccia. 

The lodes range in size from veinlets to vein zones several hundred feet long and 

as much as 20 feet wide and contain ore that ranges in grade from 40 percent to 

85 percent CaF2 ; the average grade is about 50 percent CaF2 .

INTRODUCTION

LOCATION AND GENERAL FEATURES

The fluorspar deposits near Meyers Cove are in the Salmon River 

Mountains in the Gravel Range mining district of western Lemhi 

County, Idaho. (See fig. 1.) Meyers Cove is a small settlement on 

the terraces of Camas Creek, a tributary to the Middle Fork of the 

Salmon River. Meyers Cove is in sec. 6, T. 17 N., R. 17 E., Boise 

meridian; the deposits are in an unsurveyed area about 2 miles north 

of, and downstream from, Meyers Cove. Fluorspar has been found 

on both sides of Camas Creek in a belt about 3 miles long and 2 

miles wide. This belt (pi. 1) trends southeast from the nose of the 

ridge north of Duck Creek, a tributary to Camas Creek, to the ridge 

south of Fluorspar Gulch, a name used locally for the first gulch south 

of Duck Creek and first applied by A. L. Anderson (1943, p. 3). In 

this belt Camas Creek is a little more than 5,000 feet above sea level. 

The fluorspar deposits are 100 to 2,200 feet above stream level.

The area is well dissected; the mountains have steep, relatively 

uniform slopes and sharp ridges. The larger valleys contain a few 

narrow, low terraces. Spurs on both sides of Camas Creek rise to 

altitudes of more than 9,000 feet within 4 miles of the creek. Northward-facing slopes in the area generally are covered by thick soil that

1
CONTRIBUTIONS TO ECONOMIC GEOLOGY

FIOUBB 1. Index map showing the location of the fluorspar area near Meyers Cove, Lemhi County,

Idaho.
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 3

supports the growth of heavy evergreen forests, and the bedrock is 

concealed. Southward-facing slopes, however, are generally grassy, 

and bedrock crops out abundantly.

A graded road from Meyers Cove to some of the deposits was 

completed in July 1943 by the United States Forest Service. The 

road leads down Camas Creek about a mile, then climbs steeply up 

Fluorspar Gulch to the ridge between the gulch and Duck Creek. In 

the winter of 1943-44 Chamac Mines Co. built a road from the 

Forest Service road down Camas Creek for an additional 2 miles.

Meyers Cove is accessible from both Challis and Salmon by graded 

roads, which are graveled for most of their lengths. The road from 

Challis crosses a 7,500-foot divide and is about 50 miles long. Meyers 

Cove may be reached from Salmon by two routes: a shorter road 

about 65 miles long, that crosses an 8,000-foot divide and an alternate 

route 106 miles long that avoids this pass.

The nearest railroads are Darby, Mont., on a spur line of the 

Northern Pacific Railway, and Mackay, Idaho, on a spur line of the 

Union Pacific Railroad. Darby is 78 miles north of Salmon over 

graveled and paved roads, and Mackay is 54 miles southeast of 

Challis over paved roads.

PREVIOUS FIELD WORK

The geology of the Casto quadrangle, which contains most of the 

fluorspar deposits, was mapped and described by Ross (1934), who 

mentioned the occurrence of fluorite in some of the mineralized areas. 

Both Ross (1927, 1934) and Anderson (1943) described an antimony 

deposit near Meyers Cove that contains fluorite.

The fluorspar deposits, discovered in 1942, were first described by 

A. L. Anderson (1943), who made a reconnaissance study of the area 

in July of that year. In September 1942 J. W. Taber made a preliminary examination of the fluorspar deposits (U. S. Bur. Mines, 

1943). Flotation tests on fluorspar from the district were made by the 

Idaho Bureau of Minos and Geology (Prater, 1943). In 1944 the 

U. S. Bureau of Mines trenched and sampled some of these deposits 

(U. S. Bur. Mines, 1945).

As part of the wartime fluorspar investigations by the U. S. Geological Survey, the author spent about a month mapping and studying 

the deposits near Meyers Cove during August and September 1943. 

During part of September J. O. Fisher assisted with this field work. 

The author revisited the area in June and September of 1944.

ACKNOWLEDGMENTS

Chamac Mines Co. furnished information about the deposits, for 

which acknowledgment is gratefully made. A. E. Chambers, owner
4 CONTRIBUTIONS TO ECONOMIC GEOLOGY

and manager, who was especially helpful in making accommodations 

available at the mining camp, deserves particular mention. Thanks 

are also due other individuals residing in the district and to officials of 

the Challis National Forest.

The base line and transit triangulations in the vicinity of the Red 

Spar and Purple Spar Lodes were made in cooperation with the U. S. 

Bureau of Mines.

GEOLOGY 

LITHOLOOY

The rocks of the area are mainly tuffs and flows that range in composition from rhyolite to andesite, but a few small bodies of granophyre 

and lamprophyre also are present (pi. 1). The two small exposures of 

quartzite of pre-Cambrian age that Koss (1934, pi. 1) mapped on the 

east side of Duck Creek were not found because time was lacking.

The contact between the Casto (Permian?) and Challis (Tertiary) 

volcanics was mapped in the fluorspar area with the assistance of 

C. P. Ross. The distinction between these two formations is based 

principally on regional evidence and locally upon the degree of alteration of some of the original minerals, especiaUy feldspars and dark 

minerals, in the flows and tuffs. The Challis volcanics generally are 

lighter colored, more finely jointed, and more conspicuously bedded 

than the Casto volcanics. In several places, however, the Challis is 

the darker, as along the contact between these two formations mapped 

on the ridge between Duck Creek and Fluorspar Gulch. Most of the 

Crystle lodes are in the Challis volcanics, but the Big Lead and the 

North Lead are in the Casto volcanics, as are all of the Purcell lodes 

that are not in intrusive masses.

The tuffs commonly are very difficult to distinguish from the flows. 

Some sandy rocks are almost certainly water-laid tuffs and some 

porphyritic rocks are definitely flows, but many of the rocks containing 

fine-grained rock fragments and feldspar crystals or fragments in a 

glassy groundmass may be either tuffs or flows. The banding, which 

is common in many of the unidentifiable rocks, may be either flow 

banding or bedding in a tuff. The glass in both tuffs and flows is 

generally devitrified.

Several irregular bodies of granophyre, which are a few tens to more 

than 1,000 feet across, have been mapped. Granophyre fragments in 

talus in various parts of the area indicate the presence of more granophyre bodies than have been mapped. The granophyre is pinkish 

brown, weathering to buff, and consists of rectangular phenocrysts of 

feldspar as much as one-fourth of an inch across and round phenocrysts of quartz as much as one-eighth of an inch across in a finegrained groundmass. Some dark rocks in the area contain pheno-
FLUORSPAR DEPOSITS NEAR MEYERS COVE, IDAHO 5

crysts similar to those of the granophyre but have a glassy groundmass 

that commonly shows flow banding; these are regarded as units of the 

Casto volcanics. Although the granophyre is probably of Miocene 

age, none of these intrusive bodies were found in Challis rocks of late 

Oligocene or early Miocene age. The soil above granophyre bodies has 

a yellowish cast that is distinctive from the dark soil above Casto 

volcanics. Yellow soils that do not appear to have been derived from 

the granophyre, however, occur at some places.

The granophyre bodies apparently were favorable for the formation 

of fluorspar deposits. Many of the Purcell lodes are in or adjacent to 

granophyre bodies. The fluorspar is clearly later than the granophyre 

because it is found in shear zones that cut the granophyre. The 

localization may be structural, due to some difference in physical 

properties between the granophyre and the surrounding Casto 

volcanics.

Several bodies of lamprophyre were found in the Meyers Cove area. 

Most of the bodies are lenticular and range in length from a few tens of 

feet to several hundred feet. The lamprophyre is a black, generally 

very fine grained rock, although in a few places feldspar laths can be 

seen with the unaided eye. The lamprophyre was intruded after the 

granophyre was emplaced and before the fluorspar mineralization 

occurred. About 500 feet southwest of the Purple Spar Lode (pi. 1), 

lamprophyre has intruded granophyre, and south of the Big Lead 

fluorspar cuts a lamprophyre body (pi. 2).

STRUCTURE

According to Ross (1934, p. 77) the fluorspar area is on the southeast 

flank of a broad, low anticline whose axis is 6 to 8 miles to the northwest; the original average dip of the Tertiary rocks on this southeast 

flank was not much over 5°, but in minor flexures, as at Meyers Cove, 

the dip is generally 45° or more. The attitude of bedding is difficult 

to determine in most of the fluorspar area. On the north slope of the 

ridge between Duck Creek and Fluorspar Gulch the strikes range 

from N. 40° E. to N. 65° E. and the dips range from 40° to 80° SE. 

The steep dips near Fluorspar Gulch probably represent local extreme 

steepening of a subordinate flexure.

One group of steep normal faults in the region has an average trend 

of about N. 37° E., and a second group has an average trend of about 

N. 27° W. (Ross, 1934, p. 77-78). Several faults or shear zones of the 

northeast-trending group were found in the fluorspar area. Their 

courses commonly are marked by silicified rock and, in the northern 

part of the area, by fluorspar deposits. Two groups of gently dipping 

shear zones trending northeast and northwest also are mineralized and 

contain the best fluorspar deposits in the southern part of the area.

295162 54 2
6 CONTRIBUTIONS TO ECONOMIC GEOLOGY

FLUORSPAR DEPOSITS 

HISTORY OP DISCOVERY

Although the stibnite-barite deposit near Meyers Cove had been 

known for many years (Ross, 1927) and fluorite was noted in the vein 

material (Ross, 1934, p. 132), the fluorspar deposits in the area about 

a mile io the north were not discovered until the summer of 1942 

(Anderson, 1943, p. 1).

Two principal groups of claims have been located on the fluorspar 

deposits. The southeastern, or Crystle, group was located in 1942 

by Reese Miles and Roy Johnson of Salmon, Idaho. The northwestern group, known as the Purcell (also Parcell) group, was located 

in the summer of 1943 by H. V. St. Clair, Don Shulenberger, and 

Elmer Purcell, of Shoup, Idaho. Chamac Mines Co. owned the 

Purcell group in 1943 and had an option on the Crystle group.

LOCALIZATION

The fluorspar deposits are in northeast-striking shear zones with 

steep northwesterly dips, northeast-striking shear zones with gentle 

northwesterly dips, and northwest-striking shear zones with gentle 

southwesterly dips. The steep shear zones that strike northeast 

probably represent the regional group of steep normal faults whose 

strike averages about N. 37° E. Strikes in the fluorspar area range 

from N. 10° E. to N. 45° E., and dips range from 60° to 75° NW. In 

the northern part of the area these steep shear zones contain fluorspar 

deposits. The Purple Spar, Red Spar, and Florspar Lodes (pi. 1) have 

northeast strikes and steep northwest dips, and all may be in or near the 

same shear zone, although the fluorspar lodes are probably not continuous between any of the exposed deposits. The Morning Sun Lode 

and the northwesternmost heavily silicified zone shown on plate 2 

also are on steep northeast-striking shear zones.

Most of the fluorspar deposits in the southern part of the area are 

on shear zones that strike from N. 20° E. to N. 45° E. and dip from 

20° to 45° NW. Three of these zones were traced for several thousand 

feet, and several shorter ones are exposed on the south slope of Fluorspar Gulch. (See pi. 1.) The short mineralized shear zone (North 

Lead) exposed on the north side of the ridge between Duck Creek and 

Fluorspar Gulch at an altitude of about 6,750 feet may be a more 

gently dipping branch of the long mineralized shear zone (Bear Trap 

Lead) exposed on the south side of the ridge. The Big Lead, the most 

promising deposit in the southern part of the area, is on a shear zone 

whose strike ranges from north to N. 60° W., averaging N. 20° W., 

and whose dip ranges from 35° to 45° W. or SW.

In general, individual shears in several of the gently dipping zones 

are short, and these may differ widely in attitude from the attitude of
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 7

the whole zone. An individual shear generally is steeper than the zone 

of which it is a part. Slickensides and striations are common. The 

plunge of the striations is generally about as steep as the dip of the 

shear surface; the direction of plunge rarely diverges from the direction 

of dip by more than 15°.

Most of the important fluorspar deposits are in those parts of the 

zones that are greatly fractured or brecciated. The fluorspar deposits 

are massive veins in fissures, replacements of the finer parts of breccias 

and even of fragments in the breccias, crusts around fragments, and 

fillings of openings that were formed either by late movement in the 

shear zones or by shrinkage due to decrease in volume resulting from 

replacement.

MINERALOGY

Only fluorite, chalcedony, and barite can be distinguished by eye 

in most of the fluorspar deposits. Calcite was not recognized in the 

veins, but samples contain one-half of one percent to several percent 

of calcite or other carbonates. (See table 1.)

The fluorite occurs chiefly in coarsely crystalline massive and finegrained columnar forms. The earliest fluorite deposited was of two 

varieties: white, purplish, or greenish, coarse-grained aggregates or 

masses; and white, moderately fine grained aggregates. The later 

fluorite was also deposited in two forms: as concentric colorless, white, 

purple, or greenish, very fine granular coatings; and purplish or white, 

finely or coarsely columnar coatings. In some of the deposits, late 

colorless cubic crystals are a quarter to half an inch across. Purple 

fluorite with complexly crested edges fills a narrow vein in one deposit. 

In some deposits fluorite has replaced country rock for a distance of 

a few inches to \% feet beyond the walls and also has replaced wallrock 

fragments within the veins. The resulting material is white and 

resembles silicified country rock except that it is softer.

Chalcedony forms a small part of the veins, perhaps 10 percent at 

most where fluorite is present. Intensely silicified rock and chalcedony together commonly form from 30 to 60 percent of the veins, 

and silicified rock marks the extensions of veins in many places where 

no fluorite occurs. The wall rocks for a distance of a foot or two 

beyond the veins, and inclusions of country rock in the veins, generally 

are intensely silicified. Silicified rock is common for distances of 

several tens of feet from the veins. As a result of the extensive 

silicification, the veins and adjacent wall rocks are the best outcrops 

in the area and in many places form conspicuous ledges.

The chalcedony, which is generally white, was deposited early, 

probably contemporaneously with silicification of the country rock, 

and also late, as it filled voids in the last fluorite deposited. Chalcedony that was deposited at the same time as the fluorite is intermixed
87 : CONTRIBUTIONS TO ECONOMIC GEOLOGY -

and banded with purplish fine-grained fluorite. The hardness of the 

mixtures of chalcedony and fluorite is a clue to their composition.

Barite occurs in clear or white tabular crystals, commonly a quarter 

of an inch to half an inch across; less commonly the crystals are an 

inch to several inches across. In many of the veins barite either was 

not seen or formed less than 10 percent, in some it constitutes from 

10 to 30 percent, and in parts of a few veins it forms as much as 60 

percent. Although barite was deposited later than some of the 

fluorite, the barite crystals commonly are covered by later fluorite.

ORIGIN

The fluorspar deposits were formed by solutions that ascended 

along the shear zones. The mineral composition of the deposits 

indicates that they were formed under epithermal conditions of low 

temperatures and pressures.

The fluorspar mineralization was later, at least in part, than the 

intrusion of the lamprophyre, as some fluorspar veinlets cut lamprophyre bodies. The mineralizing solutions and the lamprophyre intrusions may have come from the same deep-seated magmatic source, 

and the mineralization may have followed immediately the period 

of igneous activity during Miocene tune.

The deposits are younger than the Challis volcanics of late Oligocene 

or early Miocene age and presumably older than the erosion surface 

of Pliocene age, the oldest such surface known hi the area (Ross 

1934, p. 84-86, 93). According to Ross (1934, p. 52-53), the thickness of the main mass of the Challis volcanics near Meyers Cove is 

at least 5,500 feet, and the original thickness of an upper rhyolite 

member, the youngest rock in the stratigraphic sequence, may have 

been 2,000 feet, making a total of 7,500 feet. The deposits in the 

southern part of the area, which are highest in the stratigraphic 

sequence, are in the lower part and probably near the base of the 

Challis volcanics. The deposits in the northern part of the area, 

which are lowest hi the stratigraphic sequence, are probably 1,000 

to 4,000 feet stratigraphically below the Challis volcanics.

On this basis the total vertical range through which fluorspar is 

exposed is about 4,000 feet, and these exposed fluorspar deposits 

must have formed between 7,500 and 11,500 feet stratigraphically 

below the top of these volcanics of late Oligocene or early Miocene 

age. It is not known how much of the overlying sequence had been 

removed by erosion before mineralization occurred, but the Pliocene 

erosion surface, at altitudes between 8,500 and 9,000 feet, would not 

have been attained at that time. The fluorspar deposits at altitudes 

of approximately 7,200 feet are more than 1,000 feet below this 

erosion surface, and those at an altitude of about 5,000 feet are
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 9

approximately 3,500 feet below the surface. The depths of formation of the exposed deposits, therefore, were at least 1,000 feet and 

probably not more than 11,500 feet below the surface that existed 

at the time of the mineralization.

SIZE AND GRADE

The deposits range in size from isolated fluorspar veinlets in otherwise barren parts of shear zones to large ore bodies along shear zones. 

The ore bodies are as much as several hundred feet long and 20 feet 

wide. Those parts of shear zones that are of mineable or possibly 

mineable grade are known locally as lodes or leads, and these terms 

are so used in this report.

Table 1 gives analyses of samples taken from several deposits in 

the area. Additional information about some of the samples is 

given in the descriptions of individual lodes.

TABLE 1. Analyses of samples from fluorspar deposits near Meyers Cove, Lemhi

County, Idaho

[Symbols: Oh, channel; G, grab; Or, crusher; S, specimen; Op, chip]

Sample

no.

1 1

2 2 

2 3 

2 4 

2 5 

3 6

37

3 8

9

10

11

2 12 

3 13

3 14

3 15

3 16

17

18

19

20

21

22

CaFj

74.2

67.37 

61. 62

93.77 

92.59

77.84

85.0

73. 48

53. 19

30.92

51.72

85. 10 

97. 64

95. 34

89. 30

84. 5

70.57

80.06

38.81

92.07

43.7

28. 39

SiO2

20. 6

8.93

12.42 

4.21 

1.97 

16.82

14. 6

17. 8

9.59 

1. 33

3.39

7. 29

15.4

33. 5

60. 32

Percent

BaSOi

19. 64 

16. 11 

. 14 

2.22

1. 58

CaCOs

1.85

.73

. 64 

.46 

.57

.50

4 4. 57

R2 03

1.68 

2.40 

. 64 

1.05

.80

4. 34

Anal zedb

Clarence Zeuch, Idaho Bur. Mines

and Geology. 

U. S. Bur. Mines. 

Do. 

Do. 

Do. 

Booth, Garrett, & Blair, Philadelphia, Pa. 

Kinetic Chemicals Inc., Wilmington, Del. 

Union Assay Office, Inc., Salt Lake

City, Utah. 

Charles O. Parker & Co., Denver,

Colo. 

Do.

Do.

U. S. Bur. Mines. 

Kinetic Chemicals Inc., Wilmington, Del. 

Booth, Garrett, & Blair, Philadelphia, Pa. 

Do.

Kinetic Chemicals Inc., Wilmington, Del. 

Charles O. Parker & Co., Denver,

Colo. 

Do.

Do.

Do.

Metallurgical Laboratory, Seattle,

Wash., and Union Assay Office 

Inc., Salt Lake City, Utah. 

Norman Davidson, U. S. Geol.

Survey.

See footnotes at end of table.
10 CONTRIBUTIONS TO ECONOMIC GEOLOGY

TABLE 1. Analyses of samples from fluorspar deposits near Meyers Cove, Lemhi

County Idaho Continued

[Symbols: Ch, channel; G, grab; Cr, crusher; S, specimen; Cp, chip] 

Description of Samples

Sample 

no.

1 1

22

2 3

24

2 5

3 6

37

»8

9

10

11 2 12

3 13

3 14

3 15

3 16

17

18

19

20

21

22

Source

Crystle area __

Bear Trap. ________

_____do____________

_____do_ ___ _____

Powder House _ ___

Big Lead. ________

___ do ___ _______

___ do. ______ _

___ do ___ _ ___ _

___ do ________

___ do ____ _ __

_____do____________

RedSpar__ _______

_____do__ _ ___ _ _

_____do_ __ ____ _

_ _do__ _

_ do

_____do____________

_____do ____ _____

_____do_ __ _______

Florspar. __________

____.do___ __ _ _ _

Type

?5

Ch?

Ch? GO Ch?'

Ch?

Ch?

Cr i

Ch

Ch

Ch

Ch? S«

Ch

Ch?

Ch?

Ch

Cp

Cp

S«

Ch

S

Width 

(feet)

1.9

2.3

0.5

?

?

7

15

4

18

4

?

?

6

1

2

14

Sampled by

A. L. Anderson, Idaho Bur. Mines

and Geology. 

J. W. Taber, U. S. Bur. Mines.

Do.

Do.

Do.

Chamac Mines Co.

Do.

Do.

D. C. Cox, U. S. Geol. Survey.

Do.

Do.

J. W. Taber, U. S. Bur. Mines.

Chamac Mines Co.

Do.

Do.

Do.

D. C. Cox, U. S. Geol. Survey.

Do.

Do.

Do.

P. J. Shenon, U. S. Geol. Survey.

Do.

i Prater, 1943, p. 2.

*U. S. Bur. Mines, 1943, p. 5; analyses published in Anderson, 1943, p. 14, 20. 

3 Oral communication, A. E. Chambers, Chamac Mines Co. 

« Carbonates.

* For flotation test.

6 Sorted ore.

7 Mined and sorted.

8 Best ore.

Ore that can be shipped direct to a consumer or after simple sorting, 

washing, or screening, occurs in very few deposits and in v,ery small 

quantities. The optimum cutoff grade appears to be between 40 and 

50 percent CaF2 in the larger deposits.

Metallurgical tests made by the Idaho Bureau of Mines and Geology 

(Prater, 1943) on a sample of ore from the district (sample 1, table 1) 

indicate that this type of ore is amenable to concentration by flotation. 

A concentrate that contained 98 percent CaF2 and 1 percent SiO2 was 

produced with 60 to 67 percent recovery. The sample, containing 

about 74 percent CaF2 and 21 percent SiO2 , represented a higher 

grade of ore than could be mined in large tonnages at Meyers Cove, 

and it contained very little barite, which is generally difficult to 

separate from fluorspar.

The possible production of an acid-grade product is corroborated 

by experiments made on ore that ranged from about 55 to 75 percent 

CaF2 . These tests were conducted for Chamac Mines Co. by General
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 11

Engineering Co., Inc., of Salt Lake City in February 1944. As the 

result of these metallurgical tests a 70-ton flotation mill was erected 

at the junction of Camas Creek and Duck Creek (pi. 1).

FLUORSPAR LODES 

CRYSTLE AREA

The lodes near Meyers Cove are in two main areas: the Crystle 

area and the Purcell area. One lode, the Antimony Lode, is outside 

of these areas and is described separately.

The Crystle area is east of Camas Creek, between Duck Creek and 

Fluorspar Gulch. (See pi, 1.) The area is covered by claims known 

as the Crystle group; most of the Crystle area is shown on plate 2,

Chamac Camp Lode. Two pits and a road cut expose the Chamac 

Camp Lode east of Camas Creek about 1,000 feet north of the 

camp of the Chamac Mines Co. at altitudes of 200 to 700 feet above 

the creek. (See pi. 1.) The road cut, at an altitude of about 5,370 

feet, exposes a faulted vein segment 2 feet wide that has slid out of 

position from an unknown source. A vein from 1 to 1% feet thick 

that strikes N. 60° E. and dips 35° NW. crops out and also is exposed 

in a small pit at an altitude of about 5,650 feet. The grade of ore is 

fairly high, ranging from 60 to 80 percent CaF2 in this and the aforementioned lower vein. An opencut at an altitude of about 5,840 

feet exposes a vein of coarse barite and coarse fluorite which strikes 

N. 25° E. and dips 45° NW. The ore grade is low, about 30 percent 

CaF2 . These veins may be parts of a single, irregular, narrow lode.

Crystle No. 1 Lode The Crystle No. 1 Lode (Lode No. 1 of 

Anderson, 1943) is on the north side of Fluorspar Gulch about 2,200 

feet east of its junction with Cama-s Creek. (See pi. 1.) It consists 

of a silicified zone exposed in two pits approximately 200 feet apart. 

The zone in the western pit is of unknown width and contains a 

fluorspar vein 6 inches thick that strikes N. 10° E. and dips 45° W. 

The zone in the eastern pit is about 12 feet wide and contains 2 

fluorspar veins, one 6 inches thick and the other 1 foot thick. One of 

these veins was reported to have been 4 feet thick, but the thickest 

part was blasted out in opening the prospect.

Anderson Lead. The Anderson Lead (Lode No. 2 of Anderson, 

1943) is located at an altitude of about 6,500 feet (pis. 1, 2) on 2 

silicified shear zones that are believed to merge into a zone approximately 150 feet wide. The zones have not been prospected by workings but are well exposed in outcrops. The strike of the southern 

zone is N. 20° E.', and that of the northern zone about N. 10° E. 

Both zones generally have westerly dips of from 30° to 45°, although 

the northern zone steepens to 60°. The best parts of the Anderson 

Lead are near its northern edge; one vein is 50 feet long and 2% feet
12 CONTRIBUTIONS TO ECONOMIC GEOLOGY

wide and ranges in grade from 35 to 65 percent CaF2 . In one place 

a 7-foot wide section of the zone has an average CaF2 content of 

approximately 45 percent, but this width does not continue for more 

than 5 feet along the strike and the whole vein is only about 20 feet 

long. Other veins are smaller, and in other parts of the zone the fluorspar 

is too low grade to mine. A little chalcedony and barite are present.

South Lead. The South Lead (Lode No. 3 of Anderson, 1943; vein 

-no. 1 of U. S. Bur. Mines, 1943) is at an altitude of about 7,050 feet 

(pis. 1, 2) and is on the southernmost of two shear zones that apparently merge at the Anderson Lead. Only one cut has been made on 

the South Lead, but natural exposures are very good. Strikes of 

veins and shears range from north to N. 45° E., and dips range from 

20° to 45° NW. A fluorspar vein with a maximum width of 1 foot 

follows the hanging wall of the shear zone, which is about 25 feet wide. 

A 10- to 15-foot section next to this vein is barren. A 10- to 15-foot 

section next to the footwall is highly silicified and contains .from 10 to 

40 percent barite. Within this silicified zone is an irregular mineralized zone 1 to 5 feet wide and 85 feet long; the average width is 

3 feet, and the grade of ore is about 50 percent CaF2 . j

Bear Trap Lead. The Bear Trap Lead (Lode No. 4 of Anderson, 

1943; vein no. 2 of U. S. Bur. Mines, 1943) is at an altitude of about 

7,200 feet (pis. 1, 2, 3) and is on the northernmost of two shear zones 

that merge at the Anderson Lead. Only one cut has been made on 

the Bear Trap Lead, but natural exposures are very good. As in the 

South Lead, there is a hanging-wall fluorspar vein, 1 to 2 feet thick, 

though not continuous for the whole length of the zone. Next to 

this is a 6- to 10-foot wide barren or low-grade part; next to the footwall is a 10- to 15-foot wide part that is estimated to contain between 

20 to 50 percent fluorite, 10 to 30 percent barite, and 30 to 80 percent 

chalcedony and highly silicified tuff. The best part of this zone, 5K 

feet wide and 235 feet long, probably averages about 40 percent 

fluorite.

Powder House Lead. The Powder House Lead (Lode No. 8 of 

Anderson, 1943; vein no. 4 of the U. S. Bur. Mines, 1943) is at an 

altitude of about 6,800 feet, about 1,200 feet northeast of the Anderson 

Lead. (See pis. 1,2.) This deposit is a mineralized shear zone with 

a maximum width of 50 feet; it is commonly silicified throughout and 

locally contains small lenses of fluorspar. In a fissure a few feet from 

the hanging wall is a vein of purple, massive, and crested fluorite % to 

1 foot thick and ajbout 100 feet long. A fault near the hanging wall 

of the zone strikes about N. 35° E. and dips about 35° NW. Between 

the vein and the indefinite hanging wall is a zone 4 to 5 feet wide that 

contains 20 to 40 percent fluorite in veinlets.
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 13

A mineralized shear zone (Lode No. 7 of Anderson, 1943) about 500 

feet east of the Powder House Lead is probably the eastward extension 

of this vein. (See pis. 1,2.) The strike of a shear surface in the zone 

is N. 30° E., and the dip is 20° NW. Parts of the zone contain 

fluorspar. The best lens exposed is 40 feet long, averages about 2 

feet in width, and contains about 40 percent fluorite.

Big Lead. The Big Lead (Lode No. 9 of Anderson, 1943; vein no. 

3 of U, S. Bur. Mines, 1943) appears to be the largest and highest 

grade lode in the Crystle area. (See pis. 1, 2, 4.) Outcrops of a part 

of its length are excellent; additional exposures were made in several 

trenches, opencuts, and a road cut. The attitude of the Big Lead, 

however, is difficult to determine from present exposures. Strikes 

of well-exposed parts of the body, of walls, and of banding within the 

deposit, range from N. 60° W. to north, and dips range from 25° to 

60° SW. and W. The strike of the Big Lead probably changes from 

N. 50° to 60° W. at the north end to N. 10° W. or north in the central 

part and at the south end. The average dip of the deposit probably 

is between 35° and 45°.

The exposed length of the Big Lead is about 500 feet; maximum 

horizontal widths are about 25 feet. The northern end, which has 

horizontal widths generally between 3 and 8 feet, and the southern 

end, which has a maximum width of 20 feet, are of relatively uniform 

grade estimated to range from 50 to 75 percent CaF2 at the north end 

and from 40 to 65 percent CaF2 at the south end. Samples 6 and 7 

(table 1) were taken across the vein at the opencut at the north end, 

and sample 8 represents material from this same opencut. The ore 

at the'ends consists of veinlets of fluorspar and partly replaced tuff; 

silicified tuff is the principal impurity. Shear surfaces along the walls 

and in the ore are common.

The central part of the Big Lead contains lenses having the lowest 

and highest content of CaF2 . Samples 9 and 11 (table 1) were 

taken across moderately high grade parts of the Big Lead near the 

walls. Sample 10 was taken across a low-grade lens between the 

high-grade parts. Sample 12, containing 85 percent CaF2 , was taken 

across the high-grade part of the Big Lead. The four sample localities 

are shown on plate 4.

The ore consists of (1) veinlets in tuff; (2) breccia ore composed |of 

fragments of silicified tuff, or early fluorspar surrounded by columnar 

or banded fluorspar locally cemented by fluorspar; and (3) massive 

veins with a maximum thickness of about a foot.

North Lead. The North Lead is on the north side of the ridge 

between Fluorspar Gulch and Duck Creek (pis. 1, 2)'at an altftude of 

about 6,700 feet.
14 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The attitude of the shear zone containing the fluorspar is not 

definitely known because several sets of joints are present in the zone. 

The hanging wall of the exposed western part, however, dips about 

20° NW. Although the western part of the North Lead is not well 

exposed, it appears to consist of fluorspar veinlets in a deposit 150 

feet long and 12 feet wide; this part is estimated to average about 40 

percent CaF2 . The eastern part of the North Lead is well exposed 

and is composed of discontinuous en echelon fluorspar veins, with 

maximum widths of 1 foot, cutting very highly silicified country rock.

Other lodes. A lode that consists of several veins that strike N. 

35° E. and dip 80° NW., in a zone about 100 J !eet wide, crops out 

about a mile northeast of Camas Creek near the junction of Duck 

Creek and its first southern tributary. (See pi. 

the zone, traced for about 200 feet, is a vein zon<

feet in width and estimated to average about 30 

veins in the zone are very high grade but have 

only IK feet. Other parts of the zone having a <

percent CaF2 . The 

maximum widths of 

omparable or higher

grade do not seem large enough to mine. The w lole zone appears to

be cut off at its upper end by a silicified shear zone that strikes N.

943) about 200 feet

30° E. and dips 20° NW.

A mineralized area (Lode No. 5 of Anderson, 

east of the southeast end of the Big Lead (pi. 2) iacludes several small 

shear zones with thin fluorspar veins. Attitudes of the mineralized 

shear zones differ widely; one of the zones is shown on plate 2 as 

striking N. 35° E. and dipping 45° NW. None

are more than 2 feet wide, and few average more 

shear zone (Lode No. 6 of Anderson, 1943) in 

300 feet to the southwest (pi. 2), contains sevt

f the fluorspar veins 

han 1 foot wide. A 

[amprophyre, about 

ral small veins also

with northeast strikes. The largest is about 1 foot thick.

Several other parts of shear zones in the Cryst 

worthy quantities of fluorspar,' but none appro 

Two of these lodes are on northeast-striking sh 

feet northwest of the Anderson Lead. (See pis.

PUBCELL AREA

The Purcell area is in the northwestern part o 

plate 1 and contains the Morning Sun, Red Spar, 

Red Spar No. 2, Purple Spar, Purple Spar Ext 

No. 2, Purple Spar No. 4, Florspar, and East Flo

Morning Sun Lode. The Morning Sun Lode, 

of Duck Creek at an altitude of about 5,400 feet 

shear zdhe striking N. 25°-45° E. The dip is pn 

on shears and veins within the zone range from 

The deposit has an exposed length of about 400

.) The best part of 

ranging from 2 to 6

e area contain notech economic value, 

ar zones about 400 

,2.)

the area shown on 

Red Spar Extension, 

insion, Purple Spar 

rspar Lodes, 

bout 500 feet south 

(pi. 1), is a silicified 

bably steep, as dips 

30° NW. to 60° SE. 

feiet and an additional
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 15

length of 200 feet indicated by float; it has a maximum width of about 

50 feet. The fluorspar occurs as irregular veinlets in the silicified 

zone.

On the surface above the adit shown on plate 1 is a lens about 8 

feet wide which contains approximately 60 percent CaF2 . In the adit 

the lens is about 5 feet wide and is of lower grade. Several lenses 

about 25 feet northeast are a few feet wide and contain about 40 

percent CaF2 .

Red Spar Lode. The Ked Spar Lode is about 3,100 feet northwest 

of the junction of Duck and Camas Creeks and is southwest of Camas 

Creek at altitudes ranging from 30 to 250 feet above the valley, floor. 

(See pis. 1,5.) Bedrock crops out only as ledges projecting above the 

talus slope. The fluorspar occurs as veins and veinlets in a fractured 

zone in granophyre of Tertiary age.

Several sets of joints transect the zone; the strike of the principal 

set ranges from N. 10° E. to N. 45° E., and the dip ranges from 65° 

to 75° NW. In general, the fluorspar veins parallel this set of joints. 

The largest veins are at the north end, where two high-grade veins 

have maximum widths of 6 and 8 feet. These veins pinch abruptly 

in the outcrop, however, and the maximum widths probably do not 

extend more than a few tens of feet either along strike or vertically. 

A high-grade vein more than 100 feet long but only 1 or 2 feet wide 

branches southwest from one of these wide veins. Samples 13 to 18 

(table 1), containing from 71 to 98 percent CaF2 , are from high-grade 

parts of the vein. Sample 19, containing 39 percent CaF2 , is from a 

low-grade zone next to one of the wide veins.

An adit driven from the lower end of the outcrop of the Red Spar 

Lode is believed to follow the principal vein for about 170 feet. The 

vein width averages nearly 3 feet for the first 70 feet beyond th& 

portal but only a few inches for the next 100 feet.

At the southwestern end of the Red Spar Lode, at an altitude of 

5,270 feet (pi. 5), is a fractured zone 30 feet long and 10 feet wide 

which contains fluorspar as veinlets and replacements of blocks of 

tuff. About half of the mineralized zone is fluorspar, but the quantity 

of fluorspar appears to decrease in depth.

The existence of a southern extension of the wide part of the Red 

Spar Lode does not seem probable. An area showing fluorspar float 

about 100 feet southwest of, and on strike with, the widest part of the 

Red Spar Eastern vein has been trenched deeper without disclosing 

bedrock since the Red Spar Lode was mapped. Trenches on the 

mineralized fractured zone at the southwest end of the outcrop of the 

Red Spar Lode have conclusively shown pinching of that lens. About 

600 feet southwest of the southwesternmost deposit described above, 

and at an altitude of approximately 5,600 feet (pi. 1), a new vein,
16 CONTRIBUTIONS TO ECONOMIC GEOLOGY

probably in the Casto volcanics, is exposed in one place by a bulldozer 

trail. The vein is about 3 feet wide, strikes N. 40° E., and dips 30° 

NW. No assays are available, but the grade appears low, perhaps 

about 30 percent CaF2 . ' A vein that appears to be an extension of one of the veins in the 

adit was exposed northeast of the adit and on the south bank of 

Camas Creek during excavation for a bridge, according to A. E. 

Chambers of Chamac Mines Co.

Red Spar Extension Lode. The Ked Spar Extension Lode is on a 

spur about 4,000 feet west of the intersection of Duck Creek and 

Camas Creek, and about 1,200 feet above Camas Creek. (See pi 1.) 

The outcrops are poor, but the fluorspar has been exposed by bulldozer 

cuts made by the U. S. Bureau of Mines.

The largest deposit is exposed for almost 200 feet in six bulldozer 

cuts across the strike. These cuts are about 40 feet apart, measured 

horizontally on the trace of the vein. The average strike appears to 

be about N. 55° E., and the dip ranges from 60° NW. to vertical. 

The first or northernmost cut did not reach the vein. The second 

cut, to the south, shows 14 feet of low-grade material containing not 

more than 30 percent CaF2 . The third cut, farther south, shows 22 

feet of mostly high-grade material estimated to contain 80 percent or 

more CaF2 . The fourth cut exposes only 2 feet of high-grade material. The fifth cut did not reach bedrock, and a switchback that 

makes the sixth cut shows only a few stringers of fluorspar that are 

off the strike of the rest of the lode. Most of the country rock is 

granophyre, although the hanging wall at the second cut may be part 

of the Casto volcanics.

Another deposit is exposed in a bulldozer cut that trends east about 

300 feet southwest of the largest deposit. (See pi. 1.) A lens of 

fluorspar is exposed for 30 feet in the direction of the cut, 10 feet 

normal to the cut, and 5 feet vertically. The attitude is not known. 

The grade is estimated to be 30 to 40 percent CaF2 . The country 

rock is poorly exposed but is probably granophyre.

A bulldozer trail exposes two low-grade zones about 250 feet and 

500 feet, respectively, southeastward from the second deposit. These 

zones are a few feet wide and probably contain less than 30 percent 

CaF2 .

Red Spar No. 2 Lodes. Two deposits, called the Ked Spar No. 2 

Lodes, are exposed in bulldozer trails about 400 and 600 feet west of 

the southwest end of the Ked Spar Lode. (See pi. 1.) The eastern 

deposit is a 3-foot vein in the Casto volcanics. It strikes N. 30° E., 

dips 45° NW., and appears to be of good grade.

The western deposit strikes N. 30° W. and dips 40° SW. The 

vein is in Tertiary granophyre and is exposed for a length of about 25
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 17

feet along the side of a bulldozer trail. The vein is about 5 feet wide 

along most of this distance and pinches toward the northeast end. 

No assays are available, but the grade appears good. Some fluorspar 

float in a bulldozer trail 200 to 300 feet to the northwest suggests the 

possible continuation of the vein.

Purple Spar Lode. The Purple Spar Lode is about 3,000 feet west 

of the junction of Camas Creek and Duck Creek. (See pi. 1.) It has 

been extensively explored on the surface. The total length is almost 

300 feet; the width and grade are extremely erratic. The strike 

appears to average about N. 30° E. and the dip about 45° NW. 

Like the southwest end of the Red Spar Lode, this deposit appears to 

have been localized by three sets of joints in the granophyre.

The northeast end of this lode is low grade for a length of about 40 

feet; the average grade apparently decreases to the north. An adjoining section to the south, about 90 feet long, shows well how 

fluorspai deposition was controlled by the three sets of joints; widths 

of this section range from 5 to 8 feet, and the ore grade may average 

60 percent CaF2 . Trenches to the south expose the lode for about 

80 feet; the average width appears to be about 8 feet, and the grade is 

estimated to be similar to that of the section to the north. A bulldozer trail about 80 feet still farther south shows fluorspar-bearing 

material about 10 feet wide in the lode but apparently somewhat 

lower in grade.

Purple Spar Extension Lode. The Purple Spar Extension Lode is 

exposed in a bulldozer trail about 400 feet west of the Purple Spar 

Lode. It is in granophyre, strikes N. 20° E., and appears to dip 

steeply. The width is about 8 feet, and the ore grade is about 40 

percent CaF2 .

Purple Spar No. 2 Lode. The Purple Spar No. 2 Lode is exposed 

about 1,000 feet southeast of the Purple Spar Lode. (See pi. 1.) 

The vein strikes N. 20° E. and is about vertical. The width is about 

5 feet and the average grade ranges from 40 to 50 percent CaF2 in 

the 20-foot length of vein exposed.

According to Paul Raymond, who was then foreman for Chamac 

Mines Co., a narrow vein on strike with the Purple Spar No. 2 Lode 

crops out about 1,000 feet to the southwest.

Purple Spar No. 4 Lodes. The Purple Spar No. 4 Lodes are exposed 

in prospect trenches about 3,000 feet southwest of the junction of 

Camas Creek and Duck Creek. (See pi. 1.) The western vein, in 

the Casto volcanics, at an altitude of about 6,300 feet, is 5 feet wide 

and of very low grade. The fluorspar, which follows a breccia zone, 

is sugary white and contains some fragments of early purple fluorite.

About 200 feet to the east and about 150 feet lower, a2K- to 3-foot 

vein of white sugary fluorspar cuts a breccia zone in granophyre. The
18 CONTRIBUTIONS TO ECONOMIC GEOLOGY

strike of the vein is N. 40° E., and the dip is vertical. The vein is of 

good grade for a length of about 40 feet, but to the northeast the 

breccia zone is barren.

Florspar Lode. The FlorSpar Lode is about 2,700 feet north of the 

junction of Camas Creek and Duck Creek and about 1,000 feet higher 

than Camas Creek (pi. 1). Outcrops are very scarce, but the lode is 

exposed in a trench near the north end of the lode and in an opencut 

about 400 feet to the south. The total length of the vein is apparently almost 400 feet. The lode is in the Casto volcanics, strikes about 

N. 45° E., and dips 60° NW.

The trench shows 14 feet of fluorspar containing 44 percent CaF2 

(sample 21, table 1). The fluorite occurs as veinlets and botryoidal 

coatings on fragments of tuff. Adjoining this 14-foot section on the 

northwest is at least 2 feet of lower grade material containing an 

estimated 20 percent CaF2 . The southeast margin of the lode is a 

10-foot zone containing 10 to 20 percent CaF2 ; next is a heavily 

silicified zone as much as several hundred feet thick. The fluorspar is 

not exposed for more than 15 feet northeast and southwest of the 

trench, but the silicified zone can be traced more than 100 feet northeast and about 150 feet southwest.

The opencut exposes very poorly, and probably incompletely, a 

shear zone at least 8 feet wide containing a few high-grade fluorspar 

veins but mostly material with less than 20 percent CaF2 . Sample 22 

(table 1), containing 28 percent CaF2 , represents a specimen from 

the cut.

East Florspar Lode. The East Florspar Lode is about 1,500 feet 

northeast of the Florspar Lode, at an altitude of about 7,000 feet on 

the divide between Camas Creek and Duck Creek. (See pi. 1.) The 

lode consists of a breccia zone, cemented by fluorite and silica, which 

strikes N. 20°-^5° E. and apparently dips about 30° NW. The 

highest grade section, about 50 feet long and 4 feet wide, contains 

about 60 percent CaF2 . The breccia zone was traced 200 feet southeast of this section, but only a few small lenses of fluorspar were 

observed.

ANTIMONY LODE

The Antimony Lode is about 4,000 feet south of the junction of 

Camas Creek and Fluorspar Gulch, at an altitude of about 5,900 feet. 

(See pi. 1.) The deposit has been described by Ross (1927; 1934, 

p. 131-132) and Anderson (1943, p. 15-16). According to Anderson 

the mineralized shear zone strikes N. 70° E. and dips from 40° to 

45° NW.

The lode is composed of chalcedony, barite, stibnite, and a little 

fluorite, and cuts light-colored tuff of the Challis volcanics. It is
FLUORSPAR DEPOSITS NEAR METERS COVE, IDAHO 19

exposed or indicated by 4 cuts for a length of about 500 feet. Fluorite 

was seen in one of these cuts but only in broken pieces of the lode. 

Some of the fluorite is in open spaces between crystals of barite. The 

fluorite is finely granular, pale purplish, and apparently later than 

the barite and stibnite; it is later than some of the chalcedony but is 

cut by late-stage chalcedony veinlets. Neither the fluorite nor 

stibnite appears to be of economic interest.

LITERATURE CITED

Anderson, A. L., 1943, The antimony and fluorspar deposits near Meyers Cove, 

Lemhi County, Idaho: Idaho Bur. of Mines and Geology, Pamph. 62, 20 p.

Prater, L. S., 1943, Flotation tests on fluorite ore from Lemhi County, Idaho: 

Idaho Bur. Mines and Geology, Pamph. 63, 8 p.

Ross, C. P., 1927, Ore deposits in Tertiary lava in the Salmon River Mountains, 

Idaho: Idaho Bur. Mines and Geology, Pamph. 25, p. 17.

 1934, Geology and ore deposits of the Casto quadrangle, Idaho: U. S.

Geol. Survey Bull. 854, 132 p. 

United States Bureau of Mines, 1943, Fluorite veins near Meyers Cove, Lemhi

County, Idaho: War Minerals Rept. 145, 7 p.

 1945, Meyers Cove fluorspar deposits, Gravel Range mining district, 

Lemhi County, Idaho: War Minerals Rept. 460, 11 p.

INDEX

Page

Accessibility of the area. ___________ 3 

Acknowledgments. ... -.__ 3-4 

Age of deposits____. _._._______ 8 

Analyses--___.- _ _ 9-10 

Attitudeof bedding-..--.-------------------- 5

Casto volcanics, character of._._-___.._- 4 

Challis volcanics, character of _. - -._--.---__ 4,8

Description of lodes:

Anderson Lead._-.._.__-_ 11; pis. 1, 2 

Antimony Lode ------- 18; pi. 1

Bear Trap Lead-.-.-_........... 12; pis. 1,2,3

Big Lead ---------------------- 13; pis. 1, 2, 4

Ohamac Camp Lode_--____..... 11; pi. 1

Orystle No. 1 Lode..... ........... 11; pi. 1

East Florspar Lode.--.__.--.-___ 18; pi. 1 

Florspar Lode.---____---_____ 18; pi. 1 

Morning Sun Lode-------..--.-.__-. 14; pi. 1

North Lead---.------.-----------.. 13; pis. 1, 2

Powder House Lead _...__._ 12; pis. 1, 2 

Purple Spar Extension Lode-...___ 17; pi. 1 

Purple Spar Lode. ...____.__ 17; pi. 1 

Purple Spar No. 2 Lode...___.__ 17; pi. 1

Description of lodes Continued Page 

Purple Spar No. 4 Lodes............... 17; pi. 1

Red Spar Extension Lode ...... . 16; pi. 1

Red Spar Lode___________ 15; pis. 1, 5 

Red Spar No. 2 Lodes ..--.-----.. 16; pi. 1

South Lead...._....-....-..--.-.. 12; pis. 1, 2

Flotation tests. 10

Granophyre, description of--- ...... 4-5

Lamprophyre, description of-- ---- --- 5

Literature cited---.-.---. ... 19

Location of the area...--.---- .. _. 1-3

Mineralization-.-.--.__- 8 

Origin of deposits.___..-.. 8-9

Physiographic features. 1-3 

Pliocene erosion surface .. 8

Shear zones ..... . . 5,6-7

Siliciflcation- - - 7

Size and grade of deposits .. 9-10 

Stibnite-barite deposit._ - 18-19

Vein minerals....... .. - 7-8,18-19

o

21