170 



BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



firmation by exact methods. The mineral often has a red streak or 

 powder and many occurrences might be identified as pyrargyrite on 

 this property. 



BOISE COUNTY 



In Boise County polybasite is reported to occur commonly as a 

 constituent of rich silver ores in the Banner district where it is asso- 

 ciated with pyrargyrite, cerargyrite, and native silver. 



BONNER COUNTY 



Polybasite has been identified by Edward Sampson, of the United 

 States Geological Survey, in a specimen of rich ore from the Blue Bird 



mine near Talache on the 

 north side of Blacktail Moun- 

 tain on the west shore of 

 Lake Pend d'Oreille. The 

 mineral occurs as a thin platy 

 layer along joints in the ore, 

 associated with native silver. 

 The plates show no crystal 

 outlines, but exhibit tabular 

 faces of the basal pinacoid 

 on which the triangular rul- 

 ings characteristic of the min- 

 eral are visible. The streak 

 of the mineral is black but the 

 powder under the miscroscope 

 is very slightly translucent 

 with a suggestion of red color. 



ELMORE COUNTY 



Polybasite occurred com- 

 monly but in minor amount 

 as a constituent of rich silver 

 ores of the Atlanta lode, 

 Atlanta district. 



Fig. 31.— Polybasite. Tabular crystal from Rich 

 Gulch mine, Silver City districy, Owyhee County 



OWYHEE COUNTY 



In Owyhee County polybasite is probably common in the silver 

 ores of the Silver City, De Lamar, and Flint districts. In ore from 

 the De Lamar mine it occurs as abundant dark gray, steel gray 

 masses up to 1 cm. in diameter, showing distinct cleavage, in quartz 

 (Cat. No. 74623, U.S.N.M.). In the Leviathan mine polybasite is 

 associated with pyrargyrite and stephanite. In similar form the 

 mineral has been abundant in many of the rich silver mines of the 

 Silver City district, particularly the Poorman mine. It is reported 

 that in 1864 a specimen of pure polybasite weighing 6 pounds and 



