104 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



nium immediately, with the production of the characteristic odor, and 

 colors the flame blue, leaving behind a large mass of malleable silver. 

 In the closed tube it gives odors of sulphur and selenium, and 

 yields a series of sublimates in rings which grade from yellow (sulphur) 

 at the top, through red (selen-sulphur) , to deep red and black 

 (selenium). In the open tube there are obtained odors of sulphur 

 and especially selenium, and a white ring of volatile crystals of 

 selenous oxide which is faintly red in its lower portion from the 

 presence of unoxidized selenium. 



Many tons of such ore as that from which the above described 

 specimen came were mined, and the silver mineral was passed by as 

 argentite. It is not improbable that silver selenide has been sim- 

 ilarly overlooked in other western silver ores, although the distinc- 

 tive reactions of selenium are so easily recognized that it is the work 

 of but a moment to prove its presence or absence. 



CLAUSTHALITE (47) 

 Lead selenide, PbSe. Isometric. 



SHOSHONE COUNTY 



The rare mineral clausthalite has been reported to occur in the 

 Hypotheek mine, near Kingston in the western edge of the Coeur 

 d'Alene district. 74 Nothing is known to the writer regarding the 

 mode of occurrence or associations of the mineral nor have any 

 specimens been seen. 



CHALCOCITE (54) 

 Cuprous sulphide, Cu 2 S. Orthorhombic. 



Chalcocite, commonly known as copper glance, is a comparatively 

 uncommon mineral in Idaho and no bodies of important size are- 

 known. It has been recognized in small amounts at the following 

 localities : 



ADAMS COUNTY 



In the Seven Devils district chalcocite is always secondary and 

 occurs only sparingly as a replacement of chalcopyrite or bornite 

 in the contact copper deposits. In the Badger mine the ore consists 

 of chalcocite with tetrahedrite and bornite in a 15 cm. vein of quartz. 

 South of the Badger claim this mineral occurs in fractures and re- 

 placements in andesite. At the Wilford mine chalcocite is sparingly 

 disseminated through andesite. At the 1905 mine it occurs in 

 silicified andesite with bornite and tetrahedrite and their oxidation 

 products. In the Lucky Strike (Walter James) prospect chalcocite 

 is found sparingly with bornite along fractures in chalcopyrite which 

 it replaces and it occurs similarly replacing bornite and chalcopyrite 

 in the Panama Pacific and Gaarden mine. In the disseminated de- 



7 < Ernest Leroy Adkins. Personal letter, 1917. 



