186 



REPORT OF NATIONAL MUSEUM, 1899. 



Analyse.s of samplo.s from (I) Schneeberg, Saxony, and (II) Gunnison 

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



Constituents. 



Arsenic 71. 53 



Sulphur I 1. 38 



Cobalt I 18. 07 



Iron ' 7. 31 



Nickel 1. 02 



Copper 0. 01 



63. 82 



1.55 



11.59 



15.99 



Trace. 



0. 1(5 



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 CoAsg, = 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, Norwa}", The name sajfiorite 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 anaWsis 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 cobalt has been replaced by iron.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 ((lk>- 

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

 cobalt with the formula CosS^, = 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: 



