W. F. Hillebrand— och From Colorado. 129 
only by dint of much effort that material in sufficient purity 
for decisive tests was obtained by Prof. R. A. F. Penrose, Jr., 
who transferred it to me for chemical examination. The 
material was derived from three different mines in order to 
ascertain whether it was of constant or varying composition, or, 
in fact, whether there might not be more than one specific tel- 
luride. That the composition does vary within narrow limits 
the analyses show, but there is no reason apparent for assum- 
ing more than one species. 
The material from the Prince Albert mine, the first received, 
was with little trouble brought into an almost ideal condition 
of purity. It was in part apparently fairly well crystallized, 
but the measurements made by Prof. 8. L. Penfield, of New 
Haven, are unfortunately not decisive as to the system of erys- 
tallization, as shown by his notes at the close of this paper. 
The specific gravity of this material was 8°91 at 24° C., which 
becomes 9:00 when corrected for a small admixture of silico- 
ferruginous gangue of assumed specific gravity 2°70 (probably 
low). The other samples were imperfectly crystallized and 
held too much foreign matter of uncertain composition to 
make specific gravity determinations of any value. 
ANALYSES OF CALAVERITE. 
ile I ig Ay 
Prince Albert Raven C.O.D. 
Mine. Mine. Mine. 
memurmunt (Ve) 22. 222... 57°27 47°69 53°89 
Pemenpee ys Oe | 88°95 33°93 39°31 
mremer (Ag) 02. 222. 225-22 3°21 1°47 "85 
Mepemrbher (25 2\) lb lL 33 5°80 “91 
Ferric oxide (Fe, O Sy as wae se 225 
LCG) eo 5°41 1°67 
Baenur (8): 22s -)-22 «2222 - 6°17t 1°58(2°96 FeS,) 
Manganese (Mn) ---.----- ‘23t 
Meare (Ca) 42.2... +. “51 
Magnesium (Mg).-------- "10 
Oxygen, Fluorine and Solu- | ‘Pye: 58 
ble Silica by difference -- | 
99°88 100°47 100°00 
Selenium has been reported to occur in traces in the district, | 
*This was included with the insoluble matter in arriving at the corrected 
density. 
+ Calculated from the Fe to make FeS&:. 
; As MnO, ? 
§ A part of the calcium found in solution was derived from fluorite, whieh 
likewise constituted some of the insoluble matter in this instance. 
|| F. C. Knight, Proc. Colo, Sci. Soc., Oct. 1, 1894. 
Am. Jour. So1.—Tairp Series, Vou. L, No. 296.—Aveust, 1895. 
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