232 ECONOMIC GEOLOGY 



tains 43.87 per cent, of chromic oxide. In 1908 an important 

 deposit of chromite was discovered in Converse County, Wyoming. 



The most important chromite deposits of the world are found 

 in Asia Minor. According to Thomas and MacAlister the ore 

 exists as stocks or dike-like masses, and ultra-basic patches in 

 serpentine formed from the alteration of peridotite. Similar 

 deposits exist in the neighborhood of Kraubat, in Upper Styria. 

 It occurs also in a fairly fresh peridotite in Norway. In New 

 Caledonia, deposits are commercially increasing in importance. 

 The deposits of chromite in Southern Rhodesia are peculiarly 

 interesting, for they are associated with platinum in small pro- 

 portions with the sulphides of cobalt and nickel. 



Geological Horizon. Chromite is confined in its workable ore 

 bodies to the pre-Cambrian, Cambrian and Ordovician deposits. 

 Therefore its association is with the older ultra- basic intrusives. 



Methods of Extraction. The electrolytic method: The ore 

 is crushed and fashioned into a large crucible where its complete 

 electrolytic reduction requires one hour. The only manufacturers 

 of chromium in this country are the Baltimore Chrome Works at 

 Baltimore, Maryland, and the Kalion Chemical Works at Phila- 

 delphia, Pennsylvania. Much of the ore treated at Baltimore 

 comes from Scotland, and for Philadelphia from Quebec and 

 Newfoundland. 



Uses of Chromium. Raw chromite is used in the manufacture 

 of refractory brick. These bricks are used for lining basic, 

 open-hearth furnaces in the steel industry and as a hearth lining 

 for water-jacket furnaces in modern copper smelting. Its 

 merits are as follows: It is infusible; it does not become friable 

 when heated and cooled; is unaffected by sudden heating and 

 rapid cooling; is not affected by the products formed in 

 the fusion of copper ores; it wears away very slowly under the 

 flow of the molten metal. Its use should continue to increase, 

 for the life of the brick is many times greater than that of any 

 other refractory linings and bottoms in the iron or copper in- 

 dustries. This use has been thoroughly tested in the water- j acket 

 furnaces both in New England and in Tennessee. The chro- 

 mite deposits therefore of California should find extensive use 

 in the furnaces for the treatment of the various copper ores in the 

 Cordilleran section. In the linings of one furnace where raw 

 chromite was used over 400 heats were turned out before the 

 basic chromite bricks had to be repaired or removed. Therefore 



