GEOLOGICAL SURVEY CIRCULAR 607 

Platinum and Associated Elements 

at the New Rambler Mine and Vicinity 

Albany and Carbon Counties 

Wyoming 

Platinum and Associated Elements 

at the New Rambler Mine and Vicinity 

Al-bany and Carbon Counties 

Wyoming 

By P. K. Theobald, Jr., and C. E. Thompson 

G E 0 L 0 G I C A L S U R V E Y C I R C U L A R 607 

Washington 1 968 
United States Department of the Interior 

WALTER J. HICKEL, Secretary 

Geological Survey 

William T. Pecora, Director 

First printing 1968 

Second printing 1969 

Free on application to the U.S. Gftological Survey, Washington, D.C. 20242 
CONTENTS 

Page Page 

Abstract_____________________ __________________ 1 

Introduction____________________________________ 1 

Geology and mineral deposits_____________________ 2 

Analytical procedures____________________________ 3 

Sampling and analysis of mine waste, New Rambler 

mine ________________________________________ _ 3 

Sampling and analysis of soils_____________________ 7 

Sampling and analysis of stream sediment_ _ _ _ _ _ _ _ _ _ 10 

Analysis of rocks__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 12 

Conclusions_____________________________________ 13 

References cited___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 14 

ILLUSTRATIONS 

Page 

FIGURE 1. Simplified geologic map of Precambrian rocks in the east-central part of the Medicine Bow Mountains___ 2 

2. Map of mine waste in the vicinity of the New Rambler mine______________________________________ 4 

3. Comparison of spectrographic analyses for copper and silver with analyses by colorimetric and atomicabsorption methods________ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 7 

4. Histograms of spectrographic determinations for selected elements in mine waste_____________________ 7 

5. Histograms of analyses of metal content of soils__________________________________________________ 8 

6. Distribution of soil samples and unusual metal concentrations in soils_______________________________ 9 

7. Generalized geologic map showing drainage and location and sample numbers of heavy-mineral concentrates panned from stream sediment in the vicinity of the New Rambler mine____________________ 10 

8. Histograms of analyses of heavy-mineral concentrates from stream sediment___________________ _ _ _ _ _ 12 

TABLES 

Page 

TABLE 1. Comparison of analytical procedures__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 5 

2. Analyses of mine waste_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 6 

3. Platinum and palladium in five samples of mine waste_____________________________________________ 6 

4. Comparison of analytical data for bulk samples and heavy-mineral concentrates______________________ 8 

5. Comparison of gold and platinum plus palladium in various sample media__ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 11 

6. Analyses of rocks __________________________________________________________________________ ---- 13 

III 

PLATINUM AND ASSOCIATED ELEMENTS AT THE NEW RAMBLER MINE 

AND VICINITY, ALBANY AND CARBON COUNTIES, WYOMING 

By P. K. THEOBALD, Jr., and C. E. THOMPSON 

ABSTRACT 

Platinum-group metals in the Medicine Bow Mountains 

were first identified by W. C. Knight in 1901. In the Medicine Bow Mountains, these metals are commonly associated 

with copper, silver, or gold in shear zones that cut a series 

of mafic igneous and metamorphic rocks. At the New 

Rambler mine, where the initial discovery was made, about 

50,000 tons of mine and mill waste contain an average of 

0.3 percent copper, 7 ppm (parts per million) silver, 1 ppm 

platinum plus palladium, and 0.7 ppm gold. This material 

is believed to be from a low-grade envelope around the 

high-grade pod of complex ore that was mined selectively in 

the old workings. 

Soil samples in the vicinity of the New Rambler mine exhibit a wide range of content of several elements associated 

with the ore. Most of the variation can be attributed to contamination· from the mine "'Jrkings. Even though soil 

samples identify a low-level copper anomaly that persists 

to the limit of the area sampled, soils do not offer a promising 

medium for tracing mineralization owing to the blanket of 

transported overburden. 

Stream sediments, if preconcentrated for analysis, do reveal anomalies not only in the contaminated stream below 

the New Rambler mine, but in adjacent drainage and on 

Dave Creek. Examination of a spectrum of elements in 

heavy-mineral concentrates from stream sediment may contribute to knowledge of the nature of the mineralization and 

of the basic geology of the environment. 

The sampling of bedrock exposures is not particularly 

fruitful because outcrops are sparse and the exposed rocks 

are the least altered and 'mineralized. Bedrock sampling 

does, however, provide information on the large size and 

provincial nature of the platinum-rich area. We feel that a 

properly integrated program of geological, geophysical, and 

geochemical exploration in the Medicine Bow Mountains 

and probably in the Sierra Madre to the west has a reasonable probability of successfully locating a complex ore body. 

INTRODUCTION 

The New Rambler n1ine is in the Centennial 

mining district, near the crest of the Medicine 

Bow Mountains in Albany County, Wyo. The 

mine is shown on the topographic map of the Keystone quadrangle (U.S. Geol. Survey 7.5-minute 

series, 1961) where, on editions with the green 

overprint, the extent of the treeless scar surrounding the mine and millsites may be seen. On this 

map the abbreviated name "Rambler mine" is 

used though we prefer to use the n2 me New 

Rambler in order to distinguish this min€ from the 

Doane-Rambler mine in the Encampment mining 

district of the next range to the west. The name 

of the townsite, Holmes, that served the mine 

is perpetuated in the title of the Holmes 

Campground, southeast of the mine. 

The crestal area of the Medicine Bo"v Mountains at this latitude has a subdued, wooded 

topography with rounded ridge crests rising to 

9,500-10,000 feet in altitude. The mine is at an 

altitude of 9, 700 feet. Bedrock geology is largely 

obscured by a thick cover of forest litter that 

generally rests on an additional cover of Tertiary 

or Quaternary gravels. Emmons (1903) visited 

the area while active prospecting was 2t a peak 

and noted that the prospectors had to dig through 

"6 to 16 feet of wash" in order to sample bedrock. 

Knight (1901) first called attention to the platinum at the New Rambler mine and noted previous 

knowledge of platinum in placer mines ir the area 

and of the association of platinum with "blue 

copper ore" -covellite. Wells and Penfield (1902) 

isolated and identified sperrylite in the covellite. 

Read (1905) verified the identification C'f' sperrylite and isolated native platinum and gc ld at the 

same time. He further noted that the ratio of 

palladium to platinum in the raw ore ir 5:1 and 

that the severe KCN-HNOa-caustic scda leach 

utilized to isolate the platinum minerals put all the 

palladium into solution. Finch (1925) appears to 

have discouraged further interest in the district by 

his statement that dikes had not been valuable 

platinum producers elsewhere in the wo~ld. 

We were attracted to the area by the need to 

test in the field an analytical procedur~~ for the 

determination of platinum-group metals in geologic materials. The presence of sperrylite (PtAs2) 

at the New Rambler mine lent this area to indirect 
evaluation through established analytical procedures for the determination of arsenic. The subsequent development of the platinum method 

(Thompson, 1967) and the near ubiquitous 

presence of platinum and palladium in our samples 

from the New Rambler mine and vicinity led us to 

examine several methods of geochemical exploration for the elements and environment found and 

prompted this summary of our findings. 

GEOLOGY AND MINERAL DEPOSITS 

The geology of the area is well outlined as a result of work by graduate students under Prof. R. S. 

Houston at the University of Wyoming. In particular, an unpublished map made available to us 

by M. E. McCallum provides an excellent summary of the geology of the east-central part of the 

Medicine Bow Mountains. A highly generalized 

EXPLANATION 

Shear ~ zone 

.-............. Thrust fault 

0 2 MILES 

form of this map is the basis for figure 1. Two reports of the Geological Survey of Wyoming 

(McCallum; 1968; McCallum and Or back, 1968) 

provide more detailed geologic descripi;ions of the 

Centennial Ridge mining district, northeast of the 

New Rambler mine, and of the immediate environment of the New Rambler mine. These reports 

should be consulted for more complete descriptions 

of the mines as well as· of the geology. 

Mineralized rock is concentrated along zones of 

intense cataclastic deformation that culminated 

in the formation of shear zones composed largely 

of phyllonite and mylonite. Platinum metals are 

most abundant in these zones where the host rocks 

are mafic to ultramafic metaigneous varieties. 

McCallum recognized an older and a younger 

group of Precambrian mafic rocks. The older 

group, comprising three of his large map units, 

106' 15' 

Granite 

FIGURE 1.-Simplified geologic map of Precambrian rocks in the east-central part of the Medicine Bow Mountains. (Modified 

from M. E. McCallum, unpub. map, 1964.) 

2 
includes a "lime-silicate" assemblage, "gabbroic 

material," and a variety of unassigned hornblendeor pyroxene-rich metamorphic rocks. This group 

is confined to the area south and east of the conspicuous shear zone extending in figure 1 from the 

Kentucky Derby and Independence mines south 

and west through sample localities 033 and 034. 

The younger group is more widespread and generally less metamorphosed. McCallum identified 

these rocks as metadiorite, metagabbro, metapyroxenite, metabasalt, and metaandesite. They 

form an extensive, generally chloritized, mass 

along the west edge of the mapped area (fig. 1), 

occur as dikes and sills throughout the older group, 

form extensive sills in other rocks along the east 

and north boundaries of the mapped area, and 

commonly are included within what may be a 

younger group of shear zones. 

The extensive cover of Tertiary and Quaternary 

gravels, not shown in figure 1, was subdivided into 

three general units by McCallum: (1) glacial deposits of Pinedale(?) and Bull Lake(?) age, (2) 

Pliocene(?) and Pleistocene quartzite boulder 

gravel, and (3) Miocene(?) and ·Pliocene(?) cobbleto-boulder gravel, composed chiefly of mafic rocks. 

The first of these surficial units is largely confined 

to the northern third of the mapped area, where it 

obscures most of the bedrock geology. The second 

mantles much of the upland south of the glacial 

deposits. The third appears to be confined to a 

few square miles in the extreme northwest corner 

of the Sherman Granite shown in figure 1. Placer 

deposits may have accumulated in the preglacial 

gravels. 

The most productive mine of the district was the 

New Rambler, which is located at a complex intersection of shear zones in the older group of mafic 

rocks (fig. 1). At this intersection, younger mafic 

rocks appear to be somewhat more abundant and 

in larger masses than usual. The n1ine workings are 

inaccessible, but an excellent description of the 

generally podlike masses of high-grade carbonateand sulfide-copper ores is given by Read (1905). 

On the basis of disconnected statements reported 

between 1901 and 1918, we surmise that the pod 

of ore was zoned downward from the oxidized zone 

through covellite to chalcopyrite and then to 

tetrahedrite. Taft (1918) listed recorded production at 7,000 tons of ore which contained 17 percent copper. He gave as a" typical assay": 5 percent copper and 0.02 oz (ounce) gold, 1 oz silver, 

0.4 oz palladium, and 0.6 oz platinum per ton. 

3 

The ratio of palladium to platinum inc1icated by 

this assay is 2:3 and thus differs markedly from 

the ratio of 5:1 estimated by Read (1905) and 

from the ratios we have found in the mine waste. 

Finch (1925) listed assays of seven samples from 

the district; five samples contained no detectable 

platinum metals, but when included with the 

other two, yield an average of 0.04 oz platinum 

and 0.05 oz palladium per ton. 

The present areal distribution of mine waste and 

workings is given in figure 2. Water issuing from a 

shaft at the toe of the mine dump has r0ated the 

stream channel with malachite for 500 feet 

downstream. 

ANALYTICAL PROCEDURES 

Analytical procedures for the metals other than 

the platinum group are those currently in use in 

geochemical exploration. Gold and silver were 

estimated by atomic absorption, tellurium, by the 

catalytic method of Lakin and Thompson (1963); 

and the remainder of the metals, by colorimetric 

field methods, as described by Ward and others 

(1963), or by standard semiquantitative spectrographic methods. The method used for determination of platinum plus palladium has been described 

by Thompson (1967) and is based on separation of 

platinum-group metals by precipitation with 

tellurium and estimation of their concentration 

by the catalytic effect of these metals in the reduction of molybdophosphoric acid to molybdenum blue. The precision of the methcd may be 

estimated from the comparison of analyses of five 

samples from the New Rambler mine wa<;<te shown 

in table 1. Differences between the results for individual samples may be due largely to sampling 

error because separate splits of the origiral sample 

were used. The generally higher results by Joseph 

Haffty's method reflect a more comple~e extraction of the platinum metals by much more 

thorough digestion. The analyses of platinum and 

palladium given in this report are conridered to 

represent a minimum content of these metals. 

Analyses for gold, like those for the platinum 

metals, often give erratic results owing to sampling 

errors. A measure of this variation is provided in 

table 2 in which gold analyses are give"l for two 

splits of each of the samples. 

SAMPLING AND ANALYSIS OF MINE WASTE, 

NEW RAMBLER MINE 

The locations of samples reported in tables 1 

and 2 are shown in figure 2. The boundaries of the 
1 

EXPLANATION 

xn& 

Sample locality 

649 Sample number 

iiQJ Mineral-concentrate number 

~ 

Prospect pit 

c;• I )I 

Trench 

~Dump 

rJ 

Shaft 

Building 

-

Graded road 

Unimprov~d road 

~ Dump 

FIGURE 2.-Map of mine waste in:the vicinity of the New Rambler mine. 

4 

·""'· ""' 
TABLE !.-Comparison of content of platinum plus palladium, 

in parts per million, of five samples of mine waste from the 

New Rambler mine, as determined by three analytical procedures 

Sample No. Platinum plus palladium 

1 (repeat) 2 3 

AAE 655 ____________ 0.4 1 0.5 0.82 

1.2 656 ____________ 1.7 5.3 10.1 666 ____________ 1.0 >2 1.7 3.9 

3 667 ____________ 6.0 .9 .3 .82 

.4 668 ____________ 2.5 3.7 4.0 

Average _______ 2.3 2.1 4.0 

1. Catalytic method of C. E. Thompson. 

2. Electrolysis and X-ray fluorescence method of J. S. Wahlberg. 

3. Fire-assay and emission-spectrographic method of Joseph Haffty. 

waste materials from which these samples were 

taken were generally well defined. The coarse mine 

waste forms prominent ridges radiating from the 

working shafts; smaller mounds of debris are 

present around outlying shafts, trenches, and 

prospect pits. Several ages of material are evident 

from the main workings; older, oxidized waste is 

generally to the west and is partially covered by 

less altered material to the east and south. Samples 

taken in the millsite area are mostly debris that 

filtered through the floor of the now-missing building. The slag-strewn areas around the millsite indicate that a minor amount of smelting was done, 

but the quantity of slag is insignificant in comparison with that of the coarse mine waste and mill 

tailings. The mill tailings, south of the millsite and 

confined on the east by a cribbed dam, consist of 

white, uniform, very fine grained stratified sand. 

The dam is breached at several places and a long 

cone of sand extends downstream from the mill 

tailings. Below the area of figure 2, the stream 

draining the mine area is confined to a narrow 

canyon, and deposits of mill tailings are insignificant. On the flood plain of Bear Creek, at the 

mouth of this canyon, a broad fan of outwash from 

the tailings has accumulated. The total amount of 

mine and mill waste is estimated to be about 

50,000 tons. 

Analytical data for the samples of mine waste 

are presented in table 2. Grab samples of about 

300 g (grams) were taken at each locality. Metals 

that were found to be of potential commercial 

interest were copper, silver, platinum, palladium, 

and gold. The variety of materials represented 

seemed to influence only slightly the overall variation for these elements. The relative proportions 

of the two principal platinum group metals were 

5 

determined for the five samples used r9 analytical 

control in table 1 and are given in table 3. The 

average ratio of palladium to platinum was 5:1 by 

the fire-assay and emission-sp~~trographic 

(Haffty) method and 8:1 by the elec+rolysis and 

X-ray fluorescence (Wahlberg) method. Comparison of these results with statements concerning 

shipments and assays when the mine was active 

leads to the conclusions that: (1) copper was 

selectively mined and effectively concentrated, 

(2) a sizable halo of low-grade material, now represented by the mine waste, bordered the high-grade 

material, and (3) the milling process was ineffective for separation of gold and the platinum group. 

The overall averages for these elements indicate 

that the mine and mill waste constitutes a potential resource in itself. Furthermore, if this waste 

material consists largely of rock removed to gain 

access to the ore body, it is possible that an additional sizable volume of similar rraterial still 

remains in the mine workings. 

Tellurium, particularly, and arsenic are sufficiently abundant in the tailings so that they may 

provide useful information as indicator elements 

for geochemical exploration. Molybdenum is 

slightly more abundant than normal. Neither zinc 

nor lead appears to be significantly e"'lriched; the 

single lead-rich sample from the millsite probably 

reflects contamination from litharge. 

Additional data on the mine waste are provided 

by spectrographic analyses. Of the 27 elements 

sought, five were consistently below the limits of 

sensitivity: arsenic <200, antimony < 100, tungsten <50, indium <100, cadmium <20. An additional five elements were found in only one or two 

samples: tin <10, except 700 ppm (parts per 

million) in sample 652 and 300 ppm in sample 666; 

bismuth < 10, except 10 ppm in sample 680; 

beryllium <1, except 1 ppm in sample 678 and 

3 ppm in sample 737; niobium < 10, except 10 ppm 

in samples 678 and 737; and lanthanum <20, 

except 70 ppm in sample 737. Evidently, samples 

678 and 737 are relatively rich in felsic components. Five elements also reported in table 2 were 

determined spectrographically, and the results 

verify those determined chemically. Analyses for 

two of these elements, copper and silver, are shown 

in figure 3 and have sufficient sprerd to enable 

comparison between chemical and sp~ctrographic 

precision. Average values obtained from the spectographic analyses, 5,000 ppm copper and 10 ppm 

silver, are similar to those given in table 2. 
TABLE 2.-Analyses of mine '/Daste from the New Rambler mine 

[Analyses by C. E. Thompson, reported in parts per million. Platinum plus palladium, determined by method 1 of table 11 

Gold 

Platinum -------- Sample No. Copper Silver plus 2-g palladium sample 

10-g 

sample 

Arsenic Tellurium Molybdenum Lead Zinc 

Coarse mine tailings in main mine area 

AAE 65L _______ _ 652 ________ _ 654 ________ _ 655 ________ _ 656 ________ _ 662 ________ _ 667 ________ _ 

2,000 

1,200 

>6,000 

2,000 

1,000 

3,000 

1,200 

7.8 

55 

1.5 

1.0 

14 

2.0 

1.8 

3.5 

3 

.1 

.4 

1.7 

.5 

6 

<0.1 

.9 

.3 

< .1 

.9 

.8 

.7 

1.3 

3.0 

.4 

.2 

2.5 

.5 

.2 

40 

10 

60 

30 

30 

40 

30 

8 

25 

1 

2.5 

2 

20 

2.5 

15 

15 

<5 

<5 

10 

<5 

5 

<25 

50 

25 

<25 

<25 

<25 

25 

25 

<25 

50 

25 

25 

25 

50 

Coarse mine tailings in outlying piles and mines 

664_________ 80 

649- - - - - - - - - > 6 '000 

666_________ 2,000 

680_________ 2,000 

668 ________ _ 669 ________ _ 670 ________ _ 

2,000 

2,000 

1,000 

675_________ 2,000 

678_________ 1;000 

1.0 

2.8 

7.2 

4.2 

4.5 

2.2 

2.8 

1.8 

.5 

0.2 

.4 

1.0 

1.6 

2.5 

.3 

1.0 

0.8 

.4 

0.2 

.9 

2.6 

.1 

0.3 

1.6 

.6 

0.8 

.5 

0.04 

1.0 

10 

30 

Millsite debris 

0.3 

.5 

120 

160 

Mill tailings 

0.9 

.2 

.3 

80 

30 

60 

Outwash from mill tailings 

0.3 

.02 

Slag 

40 

10 

0.25 

2.5 

13 

15 

13 

4 

7 

7 

.1 

<5 

<5 

5 

<5 

10 

5 

5 

<5 

<5 

25 

<25 

750 

25 

<25 

25 

<25 

<25 

<25 

25 

50 

25 

25 

25 

25 

25 

50 

25 

679- - - ------ > 6, 000 3. 8 0. 7 1. 5 0. 08 <10 1.3 5 <25 75 ------------------------------------------------------ Average_ _ _ _ 3 , 000 7 1. 1 . 8 . 7 

Outwash from mill tailings on Bear Creek flood plain 

737_________ 600 

738_________ 2,000 

0.8 

4.8 

0.6 

2.0 

0.3 

.1 

Analytical data for the remaining 12 elements 

are summarized in the histograms in figure 4. The 

six ferride elements of the upper tier of histograms 

are enriched, as expected from both the mafic 

environment and the copper-platinum association 

in the ore deposit. In this group, only the concentration of nickel approaches economic significance. 

Concentration of the six elements of the lower tier 

of histograms is near normal. The range for zirconium is exceptional and the lower limit Is 

abnormally low. Zirconium appears to have a 

negative correlation with the ore metals, but the 

correlation is not statistically significant in these 

samples. 

In order to compare analyses of heavy-mineral 

concentrates and bulk samples, concentrates were 

6 

0.06 

1.0 

20 

80 

0.5 

7 

<5 

5 

<25 

<25 

50 

50 

prepared by panning four samples of about 10 

pounds each from localities in the mine waste. The 

concentrates represent about a thousandth part of 

the original sample. In table 4, analyses of these 

concentrates are compared with analyses of the 

TABLE 3.-Platinum and palladium contents, in parts per 

million, in five samples of mine waste from the New Rambler 

mine 

Method 2 (Wahlberg) Method 3 (Haffty) 

Sample No. Palla- Platidium num 

AAE 655_ _ ___ 0 . .4 

656 _____ 5 

666 - - - -- 1. 5 

667----- .3 

668_- --- 3 

0.1 

.3 

.2 

<.03 

.7 

Average__ 1.8 0.26 

Palla- Pl~tiRatio dium num Ratio 

4 0.58 0.24 2.4 

17 9.2 .91 10 

7 . 5 3 . 2 . 67 4 . 8 

> 10 . 68 .14 4. 9 

4.3 2.7 1.3 2.1 

8 3.3 0.65 4.8 
7 

Colorimetric limiting value >6000 ----------------- -*--*-t< 

5000 

X COPPER X 

X X 

X X 

X 

X 

100 Q5 

70~,-------~--~r-------,----.----~ <0.5,~~--~--------r---~-------,-, 

70 100 500 1000 5000 10.000 >20,000 <0.5 0.5 1 5 10 50 70 

SPECTROGRAPHIC ANALYSIS, IN PARTS PER MILLION 

FIGURE 3.-Comparison of spectrographic analyses for copper and silver with analyses by colorimetric and atomic-

. absorption methods. 

NICKEL COBALT CHROMIUM TITANIUM VANADIUM SCANDIUM 

j 

~~u 

STRONTIUM BORON YTTRIUM ZIRCONIUM 

•• 

PARTS PER MILLION 

FIGURE 4.-Histograms of spectrographic determinations for selected elements in mine waste at the New Rambler mine. 

Analyses by D. J. Grimes. 

bulk sample from the same locality. Of the four 

elements determined, only the gold approaches a 

hundredfold enrichment. Platinum plus palladium 

is enriched only by a factor of 10 or less, indicating 

that our efforts to concentrate these metals 

gravimetrically were no more successful than 

many other attempts have been in the Centennial 

district. We suspect, as did Read (1905) in his experiment, that we may have concentrated only 

the platinum and that the palladium was lost in 

the waste. It is difficult to establish whether 

arsenic and tellurium were concentrated at all. 

7 

SAMPLING AND ANALYSIS OF SOILS 

Soil samples, 52 in number, were collected during mapping of the mine waste at the New 

Rambler mine in order to assess soils as a medium 

for geochemical exploration. As has been noted, a 

nearly continuous, thick mantle of debris obscur:es 

bedrock on the upland surface. Blocks of white 

quartzite throughout the surficial debris were 

transported from sources miles to the north and 

northwest. Virtually all outcrops of bedrock 
TABLE 4.-Comparison of analytical data for bulk samples and heavy-mineral concentrates from the New Rambler mine 

!Analyses of bulk samples and all platinum determinations by C. E. Thompson. Heavy-mineral concentrates, analyzed by R. L. Turner and Eric Welsch for arsenic and tellurium and by R. L. Turner and J. B. McHugh for gold. All analyses reported in parts per million] 

Platinum plus 

Sample No. palladium Gold Arsenic Tellurium Weight of concentrate Material sampled Heavy Heavy Heavy Heavy Heavy (grams) Bulk mineral Bulk mineral Bulk mineral Bulk mineral Bulk mineral 

AAE 649 AAE 650 0.4 3 1.0 67 30 656 657 1.7 2 2.5 160 30 666 665 1.0 19 .3 38 120 670 671 1.0 4 .3 12 60 

t Insufficient sample. 

are in artificial exposures. Soils offer the only 

reasonably continuous sampling media. 

The soils are poorly developed and consist generally of a surface coating of forest litter and a thin 

humic layer, resting on the oxidized surface of the 

poorly sorted surficial mantle. Samples were collected from the oxidized zone beneath the humus 

at depths of from 2 to 8 inches. These were passed 

through 10- and 80-mesh sieves and the coarsest 

fraction was discarded. Two size fractions, -10 

+80 mesh and -80 mesh, were ground and 

analyzed for copper, silver, platinum plus palladium, gold, arsenic, tellurium, molybdenum, and 

zinc. The results are summarized in figure 5. There 

was little difference in the distributions of analyses 

for the two sieve fractions; therefore, only that of 

the finer fraction is discussed. 

PLATINUM 

AND 

SILVER PALLADIUM 

88:32:!! 

~cicicic) 

60 2.5 25 3 Mine tailings. 40 2.0 12 2 · Do. 80 13 10 19 Millsite debris. 

(') 7 2 4 Mill tailings. 

The ranges obtained for the eight determinations, except for copper, are slight. As expected 

from analyses of the mine waste, neither molybdenum nor zinc exhibits more than background 

concentrations. Significant anomalously high 

values are evident for all the other elements determined despite the small range. For copper the 

overall distribution and range are unusual. 

Figure 6 shows the distribution of copper, as related spatially to the mine and mine waste, and 

the localities of anomalous values for the other 

elements. The major part of the anomaly can be 

explained by contamination from the former mining operations. Only the relatively low-level (less 

than 100 ppm) copper anomaly still incompletely 

defined to the east and west of the area sampled 

would seem likely to reflect a high copper content 

GOLD 

S2S!81!2 

cicicicicicici 

vv 

ARSENIC TELLURIUM MOLYBDENUM ZINC 

88~1<1'!ii!lilli!l! eoooooo-r.~ 

lnii'IOO 

NNV)Q 

v -

ll)ltl00 

NNit)O 

v -

PARTS PER MILLION 

FIGURE 5.-Histograms of analyses of metal content of soils in the vicinity of the New Rambler mine. Analyses by Allan 

Meier, C. E. Thompson, Eric Welsch, R. L. Turner, J. B. McHugh, and James Watteson. 

8 
..c: 

00 

(j) 

E 

0 

00 

I 

100 

Au Te Ag, ?t, X l(JO 

0 

locality Sample er content, . ndicates copp d symbol Number 1 er million, an ·nor- in parts p h following mt indicates t e . 

metal contents. m silver d 

Ag, 0 6 or 0.8 pp platinum an · 0 15 ppm Pt, 0.1 o.r . 

palladlUm m gold 

Au, 0 08 or O.l PP llurium · 0 6 ppm te Te,0.1to .. 

. LANATION 

EX p R CONTENT 

-·s 

CIJ 

..c: 

Ul 

Q) 

E 

0 

00 

I 

COPPE(PPM) 

D 

I ess t h an 20 

~ 20-80 

~ 100-200 

More 

~ than 200 

300 FEET 

0 

Mine waste 

~ 

Prospect pit 

~ 

Trench 

rl 

Shaft 

Building • 

--- Graded ---road 

:-..:-:e~ roa1 Unimprov 

X 

<5 

FIGURE 6. . n of sm "1 samples an d unusual m -Distributw 9 etal concentratlo . ns in smls, . New Ram ble~ mine. 

~5 
in bedrock. However, designation of this level of 

· copper content as anomalous presumes a low 

regional background of less than 20 ppm copper, 

a value compatible with the supposed source for 

the surficial debris in quartzitic terrane but incompatible with the mafic nature of the underlying 

rocks. Therefore, areas of shallow cover might well 

appear anomalous, as would areas of deeper cover 

overlying bedrock rich in copper sulfides. 

We conclude that soils are of limited usefulness 

for exploration in this environment. 

SAMPLING AND ANALYSIS OF STREAM SEDIMENT 

Stream sediment commonly provides an excellent reconnaissance geochemical medium. To 

evaluate this medium in the New Rambler mine 

area, 10 samples were collected in the area around 

the New Rambler mine and an additional two 

samples on Dave Creek were obtained from 

J. C. Antweiler (fig. 7). Most streams cf the area 

have a low gradient and have been extensively 

dammed by beaver. The coarsest available material was collected; at some locaEtief this was 

sandy muck. Samples 692 and 734, in th~ drainage 

below the New Rambler mine, consisted mainly 

of debris washed from the mill tailings 2nd clearly 

are contaminated; sample 822 was from a terrace. 

At each sample site about 20 pounds of material 

was panned to produce a heavy-mineral concentrate, because both the gold and platinum should 

be enriched in this heavy fraction of the sediment. 

N 

FIGURE 7.-Generalized geologic map, enlarged from a part o£ figure 1, showing drainage and location and samr1e numbers 

of heavy-mineral concentrates panned from stream $ediment in the vicinity of the New Rambler min€. 

10 
The concentrates weighed from 0.9 to 31 g and 

averaged 6 g; the concentration ratio was about 

1,000 to 1. At six localities a -10 +80 mesh and a 

-80 mesh screened fraction of the raw sediment 

were also collected. Chemical analyses for arsenic, 

gold, platinum plus palladium, and tellurium were 

made on all samples; spectrographic analyses were 

obtained on only the heavy-mineral concentrates. 

Table 5 compares mineral contents in bulk 

samples and concentrates from tailings and from 

both contaminated and uncontaminated stream 

sediments. From the comparison it is clear that: 

(1) enrichment is considerable in the heavymineral concentrates from all sources even though 

it is not of the same order of magnitude as the 

concentration ratio, and (2) for the uncontaminated stream sediments, this enrichment 

raises the content of gold and platinum-palladium 

to an easily determined level. The heavy-mineral 

concentrates are reduced from a large volume of 

stream sediment; therefore, any discrete particles 

of gold and platinum-group metals which may be 

present are more effectively sampled. It is not 

surprising, therefore, that an anomalous value for 

platinum in heavy-mineral concentrate 731, from 

the drainage adjacent to the New Rambler mine 

on the west, is not evident in the analyses of the 

raw sediment. We conclude that heavy-mineral 

concentrates provide a useful medium for reconnaissance exploration of this environment, whereas 

the raw stream sediment is not likely to do so. 

Analyses of the heavy-mineral concentrates of 

all samples of uncontaminated stream sediments 

are summarized in the histograms in figure 8. In 

addition to the elements shown, bismuth and 

antimony were sought spectrographically but were 

consistently below their limits of sensitivity, 10 

and 100 ppm respectively. Silver was detected at 

the limit of sensitivity, 0.5 ppm, in sample 692 

only. All samples contain 1 percent or more of 

titanium. In figure 8, the elements are grouped 

according to the geochemical associations evident 

in this suite of samples. The five elements in the 

upper row are enriched in the tailings of the New 

Rambler mine and in the two sediment samples 

from a contaminated stream. As noted above, the 

drainage just west of the mine is also enriched in 

platinum plus palladium. The Dave Creek drainage is enriched in platinum-palladium and is further enriched in gold-the richest sample of the 

suite came from that creek-and in molybdenum. 

11 

TABLE 5.-Comparison of analytical results for gold and 

platinum plus palladium in various sample media in the 

vicinity of the New Rambler mine 

[Analyses by C. E. Thompson, R. L. Turner, and J. B. McHugh, reported in parts per million] 

Sample No. for concentrate 

AAE 650 _________ 657 _________ 

665- - ------- 671. - -------

AAE 692 _________ 

734- - - - - - - - -

AAE 725 _________ 728 _________ 731_ ________ 

739- - - - - - ---

Gold Platinum plus palladium 

Bulk Concentrate Bulk Concentrate 

Tailings 

1.0 67 0.4 3 2.5 160 1.7 2 .3 38 1.0 19 .3 12 1.0 4 

Contaminated stream sediment 

Concen- Concen- Coarse Fine trate Coarse Fine trate 

0.08 0.4 4 0.05 0.4 4 .2 .2 5.6 .1 .07 5.4 

Uncontaminated stream sediment 

0.02 0.06 0.2 0.5 0.05 0.4 .04 .04 .2 <.05 <.05 .5 .04 .04 .1 .05 <.05 1.5 .06 .06 .1 .07 .07 .4 

There is evidently another economic target 

somewhere in the Dave Creek drainage. 

The second row of elements from the top are 

those commonly associated with mafic rocks of the 

type exposed in these drainage basins. As expected, the modes are high, even for heavy-mineral 

concentrates. The contaminated drainage below 

the New Rambler mine has even more of these 

elements than the mode. Samples 717 and 719 

were collected northwest of a major shear zone in 

quartz monzonitic terrane and contain somewhat 

less of these elements than the mode. Surprisingly, 

Dave Creek appears to be even leaner in these 

elements than the quartz monzonitic terrane. 

The third row shows elements commonly associated with a felsic terrane. These are enriched in 

the two samples from the quartz monzonitic 

terrane. Boron is enriched in the entire Elk Creek 

drainage; two other samples with more than 20 

ppm suggest that there has been redistribution of 

this element either outward from the quartz 

monzonite gneisses or along the major shear zone. 

Dave Creek exhibits a felsic association. 

The bottom row is largely self explanatory. 

Scandium exhibits no variation. The mine drainage is unusually poor in manganese, perhaps owing 

to supergene leaching. Dave Creek is unusually 

poor in barium; barite is evidently not a gangue 

mineral. Despite the lack of evidence of zinc 

enrichment in soil and tailings at the mine, zinc is 

enriched in the heavy-mineral concentrates in the 

drainage below the mine and also on Dave Creek. 
ARSENJC 

~ 

~ 

!lc 

ORE-ASSOCIATED ELEMENTS 

MOLYBDENUM 

GOLD o COPPER ~ 

CVJ ~ ca ~ n --N~·~~~o~oooooooo ~~~R8_~-~~~~~-~-8 ~Ocicicicicici N~·~~~8gg ·~···-.. -~ •. ~ 

COBALT 

::~ : 

PARTS PER MILLION 

MAFIC-ASSOCIATED ELEMENTS 

CHROMIUM NICKEL 

0 

PARTS PER MILLION 

FELSIC- ASSOCIATED ELEMENTS 

TUNGSTEN 

~' PLATINUM 

AND 

PALLADIUM [b 0 ~ 

n~ Ch 8 <"!"'!--:~"'!GI! C!II'!C!C!C!C! oooooo ........ N,..,._..., 

VANADIUM 

0~ ~ 

~ 

NIOBIUM LEAD TIN l YTTRIUM ZIRCONIUM 

[! qm qm 

~~R8 

v - ~~~~~~n 

07HER ELEMENTS 

BARIUM MANGANESE SCANDIUM ZINC 

:__J J ~ t: 

PARTS PER MILLION 

' 

EXPLANATION 

The following symbols are placed above a column 

to identify certainjsampies that differ markedly 

from the mOde for the samples!as a group 

0 qm 

Drainage contaminated from the 

dumps of the New Rambler 

mine (samples 692 and 734) 

Dave Creek •(sampie 821) Drainage from quartz monzonite 

gneiss (samples 719 and 717) 

A 

FIGURE 8.-Histograms of analyses of heavy-mineral concentrates from stream sediment in the vicinity of the New Rambler 

mine. Analyses by J. B. McHugh, E. L. Mosier, C. E. Thompson, R. L. Turner, and Eric Welsch. 

The following conclusions seem warranted 

from these limited data on the heavy-mineral 

concentrates: 

1. The drainage from the New Rambler mine is 

easily distinguished from the surrounding 

drainage. 

2. The felsic and mafic source areas are separable. 

12 

3. The Dave Creek drainage has another economic 

target, probably one of a different nature 

from the New Rambler. 

ANALYSIS OF ROCKS 

The paucity of outcrops in the wooded, tillblanketed highland of the Medicine Bow Moun-
TABLE 6.-Analyses of rocks in the east-central part of the Medicine Bow Mountains, Albany an,d Carbon Counties, Wyo. 

[Rocks collected by M. E. McCallum. Analyses in parts per million by C. E. Thompson, Eric Welsch, and J. B. McHugh. Sample localities shown in 

figure 1] 

Platinum 

Field No. Sample plus Gold Silver Copper ComJI'ents 

palladium 

11 _______________ 018 _____________ 0.1 3.5 6 3,000 1ndependen ce mine. 12 _______________ 019 _____________ . 4 (1) .9 300 Do . 

.6 13 _______________ 020 _____________ . 05 .02 .4 50 Do . 14 _______________ 021_ ____________ .1 . 1 .6 160 Do . KD1 _____________ 022 _____________ <.05 .04 1 10 Kentucky Derby mine. 

KD2 _____________ 023 _____________ .1 . 06 1 120 Do . ~53 _____________ 024 _____________ .05 <.02 .2 10 Shear zone. 

.1 ~L1 _____________ 025 _____________ <.05 <.02 .6 10 ~other Lode mine. ~46 _____________ 028 _____________ .2 .02 .2 10 Phyllonitic dike rock. ~48A ____________ 029 _____________ <.05 <.02 .3 50 Do. ~94B ____________ 030 _____________ .15 <.02 .2 <10 Coarse-grained 

amphibolite. ~125B ___________ 031 _____________ .1 .02 .6 100 Fine-grainei 

. 9 cataclasite . ~188 ____________ 032 _____________ .1 <.02 .4 160 Sheared mylonite. 

.6 ~193A ___________ 033 _____________ .1 <.02 .2 20 Sheared, chloritized 

amphibolite. ~256 ____________ 034 _____________ .2 .1 .4 25,000 Malachite-stained 

quartz-veined 

mylonite. M259 ____________ 035 _____________ .1 . 02 .3 20 Mylonite . M280 ____________ 036 _____________ .1 <.02 .3 80 Chloritic phyllonite. 

I Insufficient sample. 

tains makes systematic sampling of bedrock 

impossible. Furthermore, the few natural outcrops 

undoubtedly represent the least-altered, leastbroken rock masses and are not likely to be 

enriched in the ore metals. Therefore, we made no 

attempt to seek outcrops for sampling purposes. 

During his geologic mapping of the area, however, 

M. E. McCallum collected as nearly a representative suite as he could obtain. He sorted through 

this suite and provided us with 17 specimens 

ranging, in his estimation, from the most likely to 

have unusual platinum content to the least likely 

country rocks. These specimens were crushed, 

pulverized, and analyzed for platinum plus 

palladium, gold, silver, and copper. 

The localities are plotted on the geologic map 

(fig. 1), and the analytical results, along with a 

brief sample description, are given in table 6. 

Only sample 034 is outstanding, and it is outstanding only for copper. It was collected from a 

prospect pit on the major shear zone extending 

west from the New Rambler mine and serves to 

identify what appears to be a copper-rich trend, 

as well as another local target for further study. 

The most striking feature of the whole data set is 

the uniform presence of both the platinum group 

and silver in amounts an order of magnitude 

greater than estimated crustal abundance. This 

13 

feature indicates that a platinum-silver province 

exists in this part of the Medicine Bow Mountains, 

but its full extent is not known as we have not done 

any systematic sampling beyond the area of this 

investigation. Because rocks similarly rich in platinum have been obtained from the Sierra Madre, 

the next range to the west, in a similar geologic 

environment, the overall province may be large. 

CONCLUSIONS 

Reconnaissance examination in the vicinity of 

the New Rambler mine indicates a pron1ising target for exploration for a complex ore boc1

y. Analysis of concentrates derived from stream sediment 

can define smaller targets within the platinum-rich 

province and can provide informatio'1 on the 

nature of the target. We do not yet have a decisive 

means of moving from stream sedime'1t to the 

target by geochemical means. Analyses of soils on 

the transported cover appear to be of little use. 

The thick cover of surficial debris has tampered, 

and will continue to hamper, exploratio'1. 

More geologic mapping is needed in the area in 

order to define further, and in more detail, the 

distribution of both the shear zones and the maficrock series; mapping as well as exploration will be 

hampered by cover, but perhaps geophysics and 

geochemistry can provide aids in crucial areas. 
The marked physical and chemical differences 

of the felsic- and mafic-rock series should be 

detectable through the cover. 

Systematic reconnaissance is needed to deJineate 

the platinum-rich province and define the more 

promising targets within it. Where targets are 

identified, means are needed to more clearly define 

the surface expression of ore bod~es. Although our 

attempts to utilize soils appear to have been ineffective, possibilities for geochemical exploration 

still exist with the use of concentrates from the 

soils, humus, or the vegetation itself. A variety of 

geophysical techniques appears promising, particularly for the more mafic, copper-sulfide-rich 

deposits like the New Rambler. 

Large segments of the Medicine Bow Mountains 

and the Sierra Madre to the west are underlain by 

a mafic-rock complex that is unusually rich in 

platinum and associated metals. Within this complex, high-grade pockets of copper sulfides have 

been mined locally. Prospecting has continued 

sporadically over many years, but as noted by 

Emmons (1903), digging of test pits through 6-16 

feet of overburden is costly and, we might add, 

statistically unlikely to be effective. Previous exploration has rarely been guided by sound geologic 

reasoning. We feel that systematic, geologically 

guided exploration in this province has a reasonable probability of discovering an ore deposit. 

REFERENCES CITED 

Emmons, S. F., 1903, Platinum in copper ores in Wyoming: 

U.S. Geol. Survey Bull. 213, p. 94-97. 

Finch, J. W., 1925, Platinum discoveries in ·wyoming [Encampment district]: Eng. Mining Jour., v. 120, no. 3, 

p. 95-96. 

Knight, W. C., 1901, The discovery of platinum in Wyoming: Eng. Mining Jour., v. 72, no. 26, p. 845. 

Lakin, H. W., and Thompson, C. E., 1963, Tellurium-A 

new sensitive test: Science, v. 141, no. 3575, p. 42-43. 

McCallum, M. E., 1964, Geologic map of the east-central 

portion of the Medicine Bow Mountains, Albany and 

Carbon Counties, Wyoming: Laramie, Wyoming Univ., 

Ph. D. thesis map. 

--- 1968, The Centennial Ridge gold-platinum district, 

Albany County, Wyoming: Wyoming Geol. Survey 

Prelim. Rept. 7, 13 p. 

McCallum, M. E., and Orback, C. J., 196?, The New 

Rambler Copper-gold-platinum District, Albany and 

Carbon Counties, Wyoming: Wyoming Geol. Survey 

Prelim. Rept. 8, 12 p. 

Read, T. T., 1905, Platinum and palladium in c~rtain copper 

ores: Eng. Mining Jour., v. 79, no. 20, p. 985-986. 

Taft, H. H., 1918, A Wyoming platinum mine: Eng. Mining 

Jour., v. 106, p. 900. 

Thompson, C. E., 1967, A spectrophotometric method for 

the determination of traces of platinum and palladium 

in geologic materials, in Geological Survey research 

1967: U.S. Geol. Survey Prof. Paper 575-D, p. D236-

D238. 

Ward, F. N., Lakin, H. W., Canney, F. C., and others, 1963, 

Analytical methods used in geochemical exploration by 

the U.S. Geological Survey: U.S. Geol. Survey Bull. 

1152, 100 p. 

Wells, H. L., and Penfield, S. L., 1902, On a new occurrence 

of sperrylite [Wyoming]: Am. Jour. Sci., 4th ser., v. 13, 

p. 95-96. GP 0 868-143 

14