102 DESCRIPTIONS OF MINERALS. 



BismutJdnite. A bismuth sulphide, B)2 S 3 , in acicular crystals of a 

 lead-gray color. 



Gaanajuatite. A bismuth selenide, from Guanajuato, Mexico, called 

 also freazelite. Silaoaiie is a selenide from the same locality, cf a 

 lead-gray color. 



Bisinite. Bismuth ochre, an impure oxide, grayish, to greenish and 

 yellowish white, and massive or earthy, found with native bismuth. 



Tetradymite. — Bismuth Telluride. 



Hexagonal ; R A B = 81° 2'. Crystals often tubular, with 

 a very perfect basal cleavage. Also massive, and foliated 

 or granular. Lammas flexible, and soil paper. Lustre 

 splendent metallic. Color pale steel-gray, a little sectile. 

 H. =1-5— 2. G.=7-2— 7-9. 



Composition. Consists of bismuth and tellurium, with some- 

 times sulphur and selenium, affording for the most part the 

 formula Bi,(Te, S) 3 . A variety from Dahlonega, Georgia, 

 gave Tellurium 43-1, bismuth 51-9 = BL Te 3 ; G. =7-642. 

 Joseite is a bismuth telluride from Brazil, in which half the 

 bismuth is replaced by sulphur ; and Wehrlite is another 

 containing sulphur, from Deutsch Pilsen, Hungary, having 

 G = 8-44. 



Obs. Found with gold in Virginia, North. Carolina, and 

 Georgia ; Highland, Montana Territory ; Red Cloud Mine, 

 Colorado ; Montgomery Mine, Arizona. 



Gene al R°mark8. — The metal bismuth is obtained mostly from 

 native bismu:h. Besides the above ores, there are also others in which 

 the metal is combined with silver, lead, and cobalt pp. 116, 166); 

 and a ca bonate of bismuth, which occurs rarely in connection with 

 native bismuth or the ores of the metal, as a result of oxidation ; also 

 a silicate. 



IV. CARBON GROUP. 



The Carbon group in chemistry comprises carbon and 

 silicon, in which the formula for the most prominent oxide 

 is K 0.,. Only carbon occurs native. 



Carbon occurs crystallized in the diamond and graphite ; 

 as oxides, in carbon oxide, and carbon dioxide (ordinarily 

 called carbonic acid); combined with hydrogen, or hydrogen 

 and oxygen, in bitumen, mineral oils, amber, and a num- 

 ber of native mineral resins, and mineral wax; and as the 

 chief constituent of mineral coal, in which it is combined 



