132 ECONOMIC GEOLOGY 



cassiterite, and wolframite may sometimes be present. The sul- 

 phide of bismuth is sparingly soluble in the alkaline sulphides 

 and in that way may be transported some distance from the 

 original ore body. The artificial sulphide is precipitated in the 

 chemical laboratory whenever hydrogen sulphide comes in con- 

 tact with a neutral or slightly acid solution of the metal. Ac- 

 cording to F. W. Clarke, the precipitated sulphide of bismuth 

 heated with an alkaline sulphide at a temperature of 200 has 

 given crystals of bismuthinite. The carbonates of bismuth are 

 of secondary origin. The action of carbonated waters upon 

 other bismuth minerals has produced bismutite. In Aus- 

 tralia bismutite has been observed as an ocherous deposit around 

 a thermal spring. Bismite is also secondary in origin, the oxida- 

 tion product of bismuthinite. According to Mayengon, bis- 

 muthinite occurs as a product of sublimation from burning coal 

 mines. 



Character of the Ore Bodies. There appears to be no well- 

 marked group of bismuth veins. The bismuth ores are best re- 

 garded as subordinate constituents of other mineral-bearing veins, 

 yet occurring occasionally in such commercial quantities as to 

 establish exceptional modifications of those veins. Veins of 

 bismuth minerals occur in gneiss and other crystalline rocks, 

 also in clay slate, accompanying various ores of silver, cobalt, 

 lead and zinc. In Queensland auriferous bismuth ores are con- 

 nected with granite intrusives. In New South Wales auriferous 

 bismuth veins occur near the contact of granite and slate. In 

 Bolivia the tin-bismuth veins appear to be connected with dikes 

 of dacite and trachyte traversing altered clay slates. 



Geographical Distribution. The best known locality for bis- 

 muth minerals in the United States is in Colorado. Lake 

 County is the best producer of the brittle metal. According to 

 H. Ries, some of the gold ores on Breece Hill near Leadville 

 contain from 5 to 8 per cent, of bismuth. In the same state 

 near Golden at Bismuth Queen Lode bismuth ores are encoun- 

 tered. It is found also at Beaver City, Utah, and near Tucson, 

 Arizona. In fact, the Cordilleran section bears many scattered 

 occurrences of bismuth ores. Bolivia, Germany and Austria are 

 the large producers of the metal. 



Geological Horizon. The ores of bismuth do not appear to 

 be confined to any geological horizon, but are more abundant 

 in the older geological formations. 



