18 g KEPOET OF NATIONAL MUSEUM, 1899. 



Analyses of samples from (I) Schneeberg, Saxony, and (II) Gunnison 

 County, Colorado, as given by Dana, yielded results as below: 



The mineral occurs like cobaltite in veins associated with other 

 metallic arsenides and sulphides. 



SKUTTERUDITE is the name given to a cobaltic arsenide of the 

 formula CoAs 3 , = arsenic^ 79.3; cobalt. 20.7. It is of a tin- white color, 

 varying to lead-gray, has a hardness of 6, and specific gravity of 6.72 to 

 6.86. It occurs associated with cobaltite, titanite, and hornblende in 

 a vein in gneiss at Skutterud, Norway, The name safflorite is given 

 to a cobalt diarsenide closely resembling smaltite but differing in being 

 orthorhombic, rather than isometric in crystallization. The composi- 

 tion as given by Dana is quite variable, running from 61 per cent to 70 

 per cent arsenic, and 10 to 23 per cent cobalt, with 4 to 18 per cent of 

 iron and smaller amounts of sulphur, copper, nickel, and bismuth. It 

 is found associated with smaltite in various localities. 



GLAUCODOT is a sulpharsenide of cobalt and iron of the formula 

 (Co, Fe) AsS, = sulphur, 19.4 per cent; arsenic, 45.5 per cent; cobalt, 

 23.8 per cent; iron, 11.3 per cent. Color, grayish; hardness, 5; specific 

 gravity, 5.9 to 6. Actual analysis of a Chilean variety yielded (accord- 

 ing to Dana) As 43.2, S 20.21, Co 24.77, Fe 11.90. It is therefore essen- 

 tially a ferriferous cobaltite, that is, a cobaltite in which a part of the 

 cobalt has been replaced by iron. The mineral is found at Huasco, 

 Chile, associated with cobaltite in a chloritic schist. The name allo- 

 clasite is given to a variety of glaucodot containing bismuth and 

 answering to the formula Co (As, Bi) S. The composition as given is 

 somewhat variable. Arsenic, 28 to 33 per cent; bismuth, 23 to 32 per 

 cent; sulphur, 16 to 18 per cent; cobalt, 20 to 24 per cent; iron, 2.7 

 to 3.8 per cent. It is reported only from Orawitza, Hungary. 



LINN^EITE (Specimens Nos. 56159, 65309, U.S.N.M.) is a sulphide of 

 cobalt with the formula Co 3 S 4 , = sulphur, 42.1per cent; cobalt, 57.9 

 per cent; a part of its cobalt is commonly replaced by nickel, giving 

 rise to its variety siegenite. The mineral is brittle, of a pale steel- 

 gray color, tarnishing red. Hardness, 5.5 and specific gravity 4.8 

 to 5. When crystallized it is commonly in octahedrons. The fol- 

 lowing analyses of a nickel-bearing variety (siegenite) are quoted from 

 Dana: 



