286 ECONOMIC GEOLOGY 



There are also three well-known tellurides of bismuth: 

 Tetradymite, Bi 2 Te 3 ; Joseite, Bi 2 Te; Wehrlite, Bi 3 Te 2 , and a 

 sulphotelluride of bismuth, Grunlingite, Bi/TeSs. 



Tellurite, TeO 2 , the dioxide, is an oxidation-product of 

 tellurium. 



There are complex tellurides and sulphotellurides of the 

 precious metals that need not be mentioned here. 



Origin of the Ores. The most of the tellurium minerals are 

 of primary origin. The oxide, the tellurates and the tellurites 

 are alteration-products. 



Character of the Ore Bodies. The tellurides of the precious 

 metals occur in large fissure-veins, often in pockets of immense 

 richness. The intrusive granites are traversed by younger 

 irruptives, with which the tellurides are connected. H. Ries 

 states that they are not found in contact deposits. (Calaverite 

 occurs as a coating on the walls of fissures at Cripple Creek, 

 Colo.) 



Geographical Distribution. The tellurides of the metals in 

 the United States are largely confined to the Cordilleran and 

 Pacific Coast belts. Altaite has been found in Gaston County, 

 North Carolina. The tellurides are found abundantly at the 

 Red Cloud mine, Boulder County, Colorado; the Camp Bird 

 and Torpedo-Eclipse mines in Ouray County; in many mines at 

 Telluride and Cripple Creek, Colorado; and in the Stanislaus 

 and Golden Rule mines in Calaveras County, California. The 

 tellurides occur abundantly in western Australia. 



Geological Horizon. A little tellurium may be found in the 

 mineral deposits of the older geological formations; but it is 

 far more abundant in association with the Cretaceous and 

 Tertiary formations of the west. 



Uses. The aluminum alloy, Al 2 Te 3 is made by melting 

 aluminum and throwing in from time to time small pieces of 

 tellurium. When the powdered metals are heated together, 

 they unite with great violence. The uses of the semi-metal 

 tellurium are few. 



Economics. The output is small, like that of selenium. A 

 small amount of tellurium may be obtained in the electrolytic 

 refining of copper, where the tellurium is deposited in the anode 

 slime or mud, with its associates, selenium, gold, and silver. 



