172 BULLETIN 12, UNITED STATES NATIONAL MUSEUM. 



combinations of these. Its baiduess is 5 and its specitic gravity from 

 4.8 to 5. It has a metallic luster and steel-gray color, giving a red 

 tarnish. 



Linn^eite is an important source of cobalt and nickel in some of the 

 Missouri lead mines, where it is found associated with lead and copper 

 ores. To illustrate the occurrence of linnfeite three specimens are 

 shown : 



(1) Crystallized, with clialcopyrite, in magnesian limestone. Mine La Motte, Madi- 

 son County, Missouri. (56109.) 



(2^, With chalcopyrite, in magnesian limestone. Mine La Motte, Madison County, 

 Missouri. (65309.) 



(3) Crystallized, also radially fibrous, with decomposed material. Mine La Motte, 

 Madison County, Missouri. (17111.) 



XiCKEL AND Cobalt Ores. 



The chief source of nickel and cobalt is not the nickel and cobalt 

 minerals, but the magnetic sulphide of iron, pyrrhotite, which fre- 

 quently carries a small percentage of these metals. Millerite is, how- 

 ever, frequently found with the pyrrhotite. The mining of these ores 

 in the United States has been mostly confined to two localities, the 

 pyrrhotite mine at Gap, Lancaster County, Pennsylvania, and some of 

 the lead mines of Missouri, especially Mine La Motte, where linuteite 

 occurs with the lead ore and nickel and cobalt are obtained in a matte 

 in the lead smelting. Other localities have at times produced small 

 amounts of these ores. Recently mines at Lovelocks, in Nevada, have 

 produced considerable nickel and cobalt. The ore at the surface con- 

 tained oxidized products, but as depth was gained the sulphide ores 

 appeared. 



To illustrate the occurrence of nickel and cobalt ores four specimens 

 are shown : 



Oxidized ore. 



(1) Aunabergite and erythrite, on decomposed nuiterial. Soudan Mine, Lovelocks 

 Humboldt County, Nevada. (56463.) 



Sttlphide ore. 



(1) Nickeliferous pyrrhotite, chalcopyrite, hornblende, enstatite, and quartz; two 

 characteristic samples. Averages 2 to 3 per cent, nickel and 0.5 per cent, cobalt. 

 Gap Mine, Lancaster, County, Pennsylvania. (18725.) 



(2) Linnieire and chalcopyrite, in magnesian limestone. Mine La Motte, Madison 

 County, Missouri. (65384.) 



(3) Millerite, in long, thin crystals and rosettes of small, fine crystals, in decomposed 

 material. 8(»ndan Mine, Lovelock',s, Humboldt County, Nevada. (66582.) 



Application of Nickel and Cobalt. 



The applications of nickel and cobalt are illustrated by the following 

 collection from the American Nickel Works of Mr. Joseph Wharton at 

 Camden, New Jersey. 



