THE NONMETALLIC MINEEALS. 189 



Other cobalt ores, carrying from 13 to 15 per cent of cobalt oxide, 

 occur near Nina. 1 



Uses. Cobalt is produced and sold in the form of oxide and used 

 mainly as a coloring constituent in glass and earthen wares. Only 

 some 200 tons are produced annually the world over. The market 

 value of the material is variable, but averages about $2 a pound. 



BIBLIOGRAPHY. 

 Fuchs et De Launay, Traite des Gites Mineraux, II, pp. 75-91. 



4. ARSENOPYRITE; MISPICKEL; OR ARSENICAL PYRITES. 



Composition. Somewhat variable. Essentially a sulpharsenide of 

 iron of the formula FeAsS, or FeS 2 , FeAs 2 ,= arsenic, 46 per cent; 

 sulphur, 19.7 per cent, and iron, 34.3 per cent. The name danaite is 

 given to a cobaltiferous variety. The specific gravity of the min- 

 eral varies from 5.9 to 6.2. Hardness, 5.5 to 6. Colors, silver white 

 to steel gray, streak dark gray to black; luster, metallic. Brittle, 



Occurrence. The mineral occurs principally in crystalline rocks, and 

 is a common associate of ores of silver, gold, tin, and lead. It is at 

 times highly auriferous, forming a valuable ore of gold, as -in New 

 South Wales and more rarely in California and Alaska. It is found 

 in nearly all the States bordering along the Appalachian Mountain 

 system, but in no instance is regularly mined excepting incidentally 

 in the process of working other metals. Concerning its occurrence 

 abroad Dana states that it is "abundant at Freiberg and Munzig, where 

 it occurs in veins (Specimens Nos. 62803, 66809, 66810, 73104, U.S.N.M.); 

 at Reichenstein in Silesia in serpentine; at Auerbach in Baden; in beds 

 at Breitenbrunn and Raschau, Andreasberg and Joachimsthal; at 

 Tunaberg in Sweden; at Skutterud in Norway; at Wheal Mawdlin 

 and Unanimity, Cornwall, and at the Tamar mines in Devonshire, 

 England (Specimens Nos. 67456, 67457, U.S.N.M.) and in Bolivia. 



Uses. The only use of the mineral is as an ore of arsenic. 



5. LOLLINGITE; LEUCOPYRITE. 



The prismatic arsenical pyrites, or leucopyrite, is essentially a diar- 

 senide of iron, with the formula FeAs 2 , though usually contaminated 

 with a little sulphur and not infrequently cobalt, bismuth, or antimony. 

 It has a specific gravity of 7 to 7.4, hardness of 5 to 5.5, metallic luster 

 and silver-white to steel-gray color. 



The mineral has been found at Edenville, New York (Specimen No. 

 67744, U.S.N.M.); Roxbury, Connecticut, and other places in the 

 United States and associated with other arsenides and sulpharsenides 

 in the gold and silver mines of Europe. 



1 Complete analyses of these are given in Catalogue of the New South Wales 

 Exhibit, World's Columbian Exposition, Chicago, 1893, p. 330. 



