PLATINUM IN COPPER ORES IN WYOMING. 
By S. F. Emmons. 
INTRODUCTION. 
The occurrence of platinum in the form of sperrylite (arsenide of 
platinum), associated with copper ores in the Sudbury district of 
Canada, has been known since 1889. a It has since been discovered 
by Hidden 6 in North Carolina. In the past winter the occurrence of 
platinum in the ore of the New Rambler mine of Wyoming was 
announced by Prof . Wilbur C. Knight/ and upon examination of the 
ore by H. L. Wells and S. L. Penfield/* of Yale University, it was 
found to occur in well-defined crystals in association with covellite 
and pyrite. 
The known occurrences of platinum in definite mineral combination 
are so rare as to render this new locality of considerable importance; 
hence a brief visit to the mine was made by the writer during the past 
summer, after spending some time in camp with Mr. A. C. Spencer, 
who Avas engaged in a geological survey of the Encampment group of 
mountains, a northern extension of the Park Range of Colorado, lying 
on the west side of the North Platte River. The following is a brief 
but necessarily incomplete statement of the geological relations of the 
deposits as far as they were ascertained : 
The mine is situated a little east of south of Medicine Peak, the 
highest point of the Medicine Bow Mountains on Beaver Creek, a 
little stream tributary to the headwaters of Douglas Creek. It is con- 
nected with Laramie City on the Union Pacific Railroad by mail and 
stage line, the distance being about 32 miles in a straight line, though 
by the windings of the road it is about half as much again. A slightly 
shorter but more precipitous road runs westward across the North 
Platte Valley to the town of Encampment, where there is a smelter 
in which 2,000 to 3,000 tons of ore from the Rambler mine were 
smelted during the winter of 1901-2. The little settlement which has 
sprung up about the mine is designated by the postal authorities 
"Holmes, ,, from the name of the manager and principal owner of the 
"Am. Jour. Sci., 3d series, Vol. XXXVII, 1889, pp. 67-71. 
''Idem, 4th series, Vol. I, 1898, pp. 381, 467. 
cEng. and Min. Jour., Dec. 31, 1901, p. 845. 
'?Ain. Jour. Sci., Feb., 1902, 4th series, Vol. XIII, p. 95. 
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