TWO TELLURIUM MINERALS FROM COLORADO. 
By W. F. HlLLEBRAND. 
1. EMMONSITE (?) FROM A NEW LOCALITY. 
Messrs. F. L. Ransome and Waldemar Lindgren, of the Geological 
Survey, collected, in the W. P. H. mine at Cripple Creek, a green min- 
eral which has been observed in other mines there, and which on exami- 
nation in the laboratory showed close resemblance to the emmonsite 
described by the writer nearly twenty years ago/' It differed from 
t, however, in outward appearance by assuming mammillary forms 
nstead of crystalline plates. In its optical properties, so far as they 
vere determinable, there is perhaps no positive disagreement with 
hose reported for emmonsite. Mr. W. T. Schaller reports as follows: 
There are two cleavages, one paralled to 6(010) and another parallel to a form in 
he orthozone. Axial plane parallel to 6(010). Bx ;i perpendicular to a cleavage face 
In the orthozone. The extinction on the clinopinacoid in inclined 25° to 30° to the 
r ertical axis. 2E is approximately 40°. Double refraction medium, and the min- 
ral nonpleochroic. 
The gangue in which the specimens were found is granite and schist, 
ose to their contact with a porphyritic breccia, in a vein pocket, at a 
istance of about 150 feet from the surface. Associated with it was 
ery rich native gold ore and also tellurite, though neither of these 
fas apparent on the few specimens that came to the laboratory. 
Like emmonsite, the mineral melts at a low heat to a red-brown liquid, 
ut, unlike it, gives on stronger heating only tellurous oxide with no 
race of selenium or selenious oxide. Analysis confirmed the absence 
f selenium. Its density, too, differs from that of emmonsite, if the 
eterminations in both cases on scanty material are to be depended 
n. After allowing for gangue, the original emmonsite was judge*] to 
ave a density of at least 5, while that of the present mineral is but 
ttle above 4.53, after allowing for 24.44 per cent of gangue, consist- 
ig mainly of quartz, and to which the specific gravity of quartz was 
;signed. 
In its appearance the present mineral would seem to resemble 
irdenite more than emmonsite, but the marked difference in water 
a Proc. Colorado Sei. Soc, vol. '2, p. 20, 1885. 
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