SUMMARY
The principal and most essential use of magnesite is in metallurgy, as a refractory material for lining furnaces. Magnesite is also used in the manufacture of Sorel cement and of paper from wood-pulp, in fire-resisting paints, as a non-conductor of heat in pipe and furnace coverings, and in the manufacture of magnesium chloride, light carbonate and other products, including metallic magnesium.
Magnesite occurs in two forms, amorphous and crystalline, and the deposits originate in three ways: by the decomposition of serpentine, as sedimentary deposits, and by the replacement of calcareous sedimentary rocks by magnesium-bearing solutions. In advance of development work it is impossible to make reliable estimates of available tonnage of the first type, but fairly accurate estimates can be made of deposits of the second and third types.
Developed magnesite deposits that have been productive at one time are situated in California and Washington; in Quebec and British Columbia, Canada; on Santa Margarita Island, Lower California; on the Island of Margarita, Venezuela; in Austria-Hungary, Germany, Spain, Greece, Macedonia, Russia, Norway, Transvaal, and India. Other deposits, some of which have produced small amounts, are situated in Nevada, Ontario, New Brunswick, on Cedros Island, Lower California; in Asia Minor, Sweden, Rhodesia, Portuguese West Africa, Australia, Tasmania, and New Caledonia. There is no reason to believe that there will be in the near future any marked shift in the important sources of supply. In 1916 and 1917 the production from the deposits of the Pacific Coast of the United States increased very rapidly, but since January, 1918, there has been a severe slump in California production.
The magnesite deposits of California and Washington are owned by a number of companies, all of them American. American refractory manufacturers are believed to be interested in some of the Canadian deposits. The deposits on Santa Margarita and Cedros islands, Lower California, seem to be owned or operated for the most part by residents of California. The deposits off the coast of Venezuela are held by a Philadelphia company. Two of the large magnesite companies of Austria-Hungary have agreed to make all of their sales outside of Austria-Hungary through a German firm in Coblenz. Two other companies, the Austro-American Magnesite Co. and the General Magnesite Co., are owned mainly by Americans. The magnesite deposits of Greece are controlled by seven companies, one of them being English, one American, one Dutch, and the remainder seemingly Greek. The other magnesite deposits of the world are of little importance at present.