108 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



by covellite, as is also the associated chalcopyrite. Another speci- 

 men of ore washed from a sericitic gouge shows nearly colorless to 

 yellow and brown crystals of sphalerite in quartz with tetrahedrite 

 and a little purplish barite. Ore from the Native Missourian No. 2 

 claim contains very dark brown fine massive sphalerite intergrown 

 with pyrite in quartz and resinous dark brown sphalerite occurs with 

 pyrite and chalcopyrite forming heavy masses of sulphides in quartz. 



In the Summit Flat (Pioneerville) district the occurrence of 

 sphalerite is in gold veins similar to the last. Ore from the Enter- 

 prise vein, Blackbird tunnel shows granular brilliant black sphalerite 

 with pyrite in sericitized granite. 



In the Ingle Group claims sphalerite of the usual dark brown 

 massive type is the most abundant mineral in heavy masses of 

 auriferous sulphides several centimeters in diameter in quartz. 

 Specimens from the Fairmont claim show black sphalerite with a 

 pinkish carbonate in thin seams in granite. Fine brown sphalerite 

 in masses in quartz from the stope between the upper and lower 

 levels of the Mohawk mine is largely fractured and slightly separated, 

 the space between the fragments being filled by later quartz. This 

 sphalerite is blue on fracture and on polished surfaces is found to be 

 replaced along cracks and seams by covellite like that from the 

 Carroll- Driscoll mine mentioned above. Considerable masses of 

 granular brown sphalerite with less galena and pyrite occur in quartz 

 in ore from the Pool Group, Diana Mines Co.; and black sphalerite 

 with much pyrite and a little galena makes up masses of sulphides 

 replacing altered granite in the Golden Age mine, occurring in this 

 mine also in crystalline grains disseminated in crushed quartz with 

 pyrite, galena, and tetrahedrite. Gold ore from the Overlook mine 

 contains coarse black sphalerite intergrown with galena, pyrite, and 

 tetrahedrite in quartz. 



In the Pearl district sphalerite occurs as an auriferous sulphide in 

 gold ores as in the Checkmate mine where zinc sulphide of the usual 

 very dark brown color intergrown with galena and pyrite forms seams 

 1.5 cm. wide in altered granite containing disseminated minute 

 crystals of arsenopyrite, as heavy masses intergrown with arseno- 

 pyrite and as segregated masses. The best sulphide gold ore from 

 the Lincoln mine in hand sized specimens shows mainly coarsely 

 crystalline sphalerite of dark brown color associated with some 

 silvery sericite. Porous cavities in the massive granular sphalerite 

 contain small crystals of sphalerite exhibiting positive and negative 

 tetrahedra, associated with pyritohedral crystals of pyrite. Other 

 specimens from the Black Pearl mine contain sphalerite intergrown 

 with much pyrite and some galena as heavy masses of auriferous 

 sulphides in sericitized granite; and those from the Granite State 

 mine contain resinous dark brown sphalerite as the most prominent 



