134 



BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



In the Haynes Stellite Co.'s mine on Blackbird Creek, 4 miles 

 below the old camp of Blackbird and 2 miles above the mouth of 

 the creek, cobaltite occurs as extremely finely diffused microscopic 

 grains of reddish-gray color in black tourmalized quartz associated 

 with larger crystals of danaite. Such material, which makes up the 

 ore, shows no cobaltite to the naked eye unless polished. Another 

 specimen from this property contains crystals of reddish cobaltite 

 up to 5 mm. in diameter disseminated in quartz with schistose 

 biotite, chlorite, and long prisms of apatite (pi. 6, lower). These 



11 12 13 



Figs. 11-13.— 11, Cobaltite. Latest Out claim, Blackbird district, Lemhi County. Cube 

 truncated by octahedron. 12, cobaltite. same locality. 13, cobaltite. cube truncated 

 by octahedron and pyritohedron. tom jefferson claim, blackbird district 



crystals are, for the most part, simple cubes or octahedrons, and 

 show well-defined cubic cleavage. 



A specimen of ore from the Nickel Plate mine shows granular 

 residual patches of cobaltite in greenish masses of oxidation products 

 consisting principally of olivenite and scorodite. 



GERSDORFFITE (90) 



Nickel-cobalt-iron sulpharsenide, (Ni, Fe, Co) AsS. Isometric. 



An isometric sulpharsenide of nickel, iron, and cobalt recently 

 received for examination and report at the National Museum may be 

 classed as gersdorffite. 



