SULPHUR AND PYRITE 355 



volume considerably from the action of the heat, the Ijottoni 

 of the vessel should be made of much larger cross section than 

 the top, in order to facilitate the dischar^';e of the spent ore 

 after the sulphur has been extracted. The steam jets are 

 so arranged that the melted sulphur cannot accumulate at 

 any point within the vessel except at the bottom. If properly 

 arranged and operated the extraction of sulphur by means of 

 superheated steam should he accomplished with the loss of 

 not more than from 1.5 to 2 per cent of the quantity of sul- 

 phur treated. 



The name pyrite is derived from a Greek word meaning 

 of the nature of fire, and alludes to the property possessed 

 by the mineral of producing sparks when struck with a hard 

 substance. Specifically, the name pyrite is restricted to the 

 isometric crystalline form of the native iron bisulphide mineral 

 (FeS2) containing 46.6 per cent of iron and 53.4 per cent of 

 sulphur. The mineral marcasite is also a native iron bisulphide 

 (FeS2) of identically the same chemical composition as p>Tite, 

 but it occurs in crystals of the orthorhombic S3'stem of cr>'stal- 

 lization. In a general sense, pjTite includes that class of native 

 minerals in the massive or crj'stalline form composed of a 

 metallic sulphide or arsenide, or both. Iron, copper, nickel, 

 and cobalt pyrite are the principal minerals of this class. 



Pyrite occurs abundantfy in rocks of all geologic ages, 

 from the oldest crystalline to the most recent alluvial deposits. 

 In crystalline formation it usuall}' occurs in small cubes, 

 pyritohedrons, or in more highly modified shapes; also in ir- 

 regular spheroidal nodules, and in the massive form in clay 

 slate, argillaceous sandstone, coal formation, etc. 



Pyrite is used principally in the manufacture of sulphuric 

 acid. Recently it has also been used in pjaite and allied smelt- 

 ing processes and, to some extent, in making sulphur dioxide 

 gas for use in bleaching wood pulp. In vulcanizing rubber 

 and in the preparation of medicinal compounds the use of 

 pyrite is impracticable. 



The deposits of p^^ite in the United States are quite 

 numerous and widespread. The largest deposits so far dis- 

 covered are at Mineral, Va., and Charlemont, Mass. Deposits 

 are also found in Alabama, CaHfornia, Georgia, Indiana, New 



