importance owe their positions and values mainly to the action of surface processes, rather than to igneous activity.
ZIRCONIUM ORES
Economic Features
The oxides of zirconium have high refractory properties which make them useful for refractory bricks and shapes for furnace linings, for chemical ware, and for other heat, acid, and alkali resisting articles. For these purposes they find a limited market. Experimental work seems to show possibilities of a very considerable use of zirconium as a steel alloy; indeed, results are so suggestive that during the war the government conducted an active campaign of investigation with a view to using it in ordnance and armor steel. For such purposes the alloy ferrozirconium is used, which carries 25 to 35 per cent zirconium metal.
The principal known deposits of zirconium ores, in order of commercial importance, are in Brazil, in India, and in the United States (Pablo Beach, Florida). The Brazilian and Indian deposits are also the principal sources of monazite (pp. 288-289). The United States controls one of the important Brazilian deposits. Germany before the war controlled the Indian deposits, and is reported to have taken much interest in the development of zirconium steels. During the war German influence in India was effectively broken up. The use of zirconium has been in an experimental state, and known sources of supply have been ample for all requirements.
Geologic Features
The zirconium silicate, zircon, is a fairly common accessory constituent of granitic rocks and pegmatite veins. From these rocks it is separated by weathering, disintegration, and stream transportation, and, having a high specific gravity, it becomes concentrated in placers. The deposits of southern India, of the coast of Brazil, and of Pablo Beach, Florida, all