GEOGRAPHICAL DISTRIBUTION

The known distribution of magnesite deposits is as follows:

The following description by countries is in the order given above:

North America.

Canada.

—The principal magnesite deposits in Canada are in the Grenville district, Argenteuil County, Quebec, where the mineral is associated with serpentine, dolomite, and other minerals. The magnesite in the Grenville district is a glistening cream-white to milk-white or gray material that occurs in extensive masses associated with bands or lenses of dark green to light-yellow serpentine. Throughout the great mass of the deposits the magnesite and dolomite are so similar in appearance that the detecting of dolomite is difficult. There is considerable positive evidence in support of the hypothesis that the deposits have been formed by the solution and replacement of crystalline limestone through the agency of magnesia-rich solutions. Outcrops of the deposits are up to 1,000 feet long and 300 feet wide. It is estimated that there are in sight 686,900 tons of magnesite containing less than 12 per cent. CaO and 483,700 tons of magnesite-dolomite containing more than 12 per cent. CaO.

In the Atlin mining district, in British Columbia, both magnesite and hydromagnesite have been noted, but the extensive masses of hydromagnesite near the town of Atlin are the most important. These deposits are superficial beds of fine powdery white hydromagnesite 6 to 8 feet thick, that cover areas up to 18 acres in extent. Two groups of these deposits are estimated to contain 180,000 tons of hydromagnesite.

United States.

—Magnesite in commercial quantity occurs in California, Nevada, and Washington. Reports of workable deposits in other states have not been verified.

In California there are magnesite deposits in many places throughout the Coast Range and on the west slope of the Sierras, from Mendocino and Placer counties on the north to Riverside County on the south. Before the war, mining was limited to a few localities and the annual output was about 10,000 tons, but the demand caused by large reduction in imports started active prospecting and development, with the result that in 1917 thirteen counties yielded a total of 211,663 tons, valued at $2,116,630. In nine counties the deposits are large and in four counties only small deposits have been found as yet. The most important deposits are in Napa, Santa Clara, San Benito, and Tulare counties. In 1917, 63 per cent. of the crude magnesite produced was mined in Tulare County. Practically all of the California magnesite deposits are irregular veins in serpentine, resulting from the alteration of magnesian igneous rocks.

In the state of Washington deposits of crystalline magnesite have been found at several places. The Washington magnesite differs greatly from the California deposits and occurs in larger masses. It is coarsely crystalline, like marble or coarse textured dolomite, and is red, pink, black, white, and gray. The Stevens County magnesite has been formed by the replacement of lenses of dolomite in sedimentary rocks. The recrystallization of the purer magnesian carbonate may have been secondary and influenced by the intrusion of basic magnesian rock which occurs above and below the magnesite in some places. The larger deposits are 200 or more feet thick and 1,000 or more feet long. Estimates of one million tons within 100 feet of the surface are reasonable for at least three of the deposits. Mining in Washington began in December, 1916, with a production of 715 tons. The output in 1917 was 105,175 tons, valued at $783,188.

The only known deposit of magnesite in Nevada is an extensive sedimentary bed in the valley of Muddy River, Clark County. The magnesite carries more than 5 per cent. lime and more than 11 per cent. silica. It has not been developed.

The total production of magnesite in the United States in 1915 was 30,499 short tons; in 1916, 154,974 short tons; in 1917, 316,838 short tons; and in 1918, 231,605 short tons.

Mexico.

—On the Island of Santa Margarita, in Magdalena Bay, Lower California, are extensive deposits of magnesite from which exports have been made to the United States. Walls of canyons in the mountains show masses of magnesite several feet thick, and magnesite boulders strew the stream beds. Large quantities can be obtained without mining and need only to be broken up for shipment. An analysis of calcined magnesite from Santa Margarita Island shows practically no silica, lime, or iron.

South America.

—The deposits on Margarita Island, Venezuela, are of the amorphous or California type and occur in veins and stockwork. No information is available regarding their extent, but 500 tons were exported to the United States in 1915.

Europe.

—The magnesite deposits of Austria and Hungary, which until recently furnished much of the world’s supply, extend along a northeast line for several hundred miles across the two countries. The mineral occurs in lenses. A large deposit near Veitsch, Austria, measures 700 to 800 feet from the top to the base. The ore is quarried in a series of benches. Another very large deposit in Austria is at Radenthein. The magnesite is quarried by great cuts, and lowered by gravity to rotary kilns. Calcining is done near the mine and both grain and magnesite bricks are shipped. The property was owned by Americans before the war and much of the output went to American ports.

The magnesite in these deposits is crystalline and occurs in dolomite, probably of Carboniferous age, from which it was derived by the infiltration of magnesium carbonate solutions and the leaching out of soluble calcium carbonate. It is finely to coarsely crystalline, yellow or bluish-white, carries 3 to 4.5 per cent. iron oxide, less than 2 per cent. silica, and less than 3 per cent. lime. It calcines readily to the dead-burned state and makes satisfactory grain magnesite and brick for refractory purposes.

Deposits of magnesite were worked for many years near Frankenstein, Silesia, Germany.

In the Province of Santander, in northern Spain, coarse crystalline magnesite lying in Lower Cretaceous limestone and dolomite has been mined for a number of years. The production in 1915 was 1,400 tons.

In Greece, magnesite is of the non-crystalline type and occurs associated with serpentine in veins and masses. The most important deposits are on the Island of Euboea. The Euboean deposits are all close to the seashore, and under normal conditions cheap water transportation to the principal magnesite markets of the world is available. The production of Greek magnesite in 1914 was mainly in the hands of three companies: the Anglo-Greek Magnesite Co., 24 Finsbury Sq., London; the Société Hellenique des Mines, Athens; and the Hellenic Magnesite Co., Athens. The distribution of the magnesite is controlled by the London company. The Anglo-Greek Magnesite Co. works mines at Galataki and Afration, in Euboea. At the Galataki mines the vein of ore exposed is known to be 1,300 feet long and 50 to 60 feet wide. The Société Hellenique des Mines (now called The Financial Corporation of Greece, Ltd.,) controls the production of several mines at Mantoudi, Limni, Larimna, etc. The Hellenic Magnesite Co. obtains most of its ore from surface excavations. In 1912 the production of magnesite by several companies in Greece, (not including the Hellenic Magnesite Co.) was as follows: Raw magnesite, 87,338 tons; calcined magnesite, 30,645 tons; dead-burned magnesite, 3,201 tons. This is equivalent to about 150,000 tons of crude ore, and does not include the product of one of the three largest producers.

The magnesite from Greece and that from California are practically identical in physical and chemical character, but prior to 1915 the California material could not compete with the Grecian in the New York market, because of the transcontinental freight rate being so high in comparison with the ocean freight on material brought as ballast.

Magnesite is found in large quantities in Macedonia, occurring as veins in serpentine.

Magnesite deposits, formerly worked, occur in Italy in the Turin district, and on the Island of Elba. None of the deposits seems to be large. An analysis of magnesite from the Island of Elba shows over 8 per cent. silica, a trace of iron, and from 1 to 3.5 per cent. lime.

Magnesite occurs in Norway as small veins in serpentine, but, unlike other magnesite in serpentine, it is crystalline. It is remarkable in that it shows no lime, but it carries over 4 per cent. iron and 9 per cent. silica. It is calcined and made into brick.

Deposits similar to those in Norway are found in Sweden, but on account of their situation, which entails heavy operating and transportation expenses, it is doubtful if they will ever be able to compete with cheaper European magnesite.

Magnesite has been mined in the Orenburg government, Russia. One mine yielded 26,320 metric tons in 1906. Magnesite occurs also on the north slope of the Caucasus Mountains.

Africa.

—Extensive deposits of magnesite occur in the Transvaal, as veins, that range up to 4 feet in thickness. The rock is used for making carbon dioxide and oxychloride cement. Great deposits of magnesite are reported in Portuguese West Africa. The deposits are near, or associated with, boiling springs.

Asia.

—The most important occurrence of magnesite in India seems to be in the Madras presidency, in the southern part of the peninsula of Hindustan, where the mineral occurs in interlacing veins. The main deposits have produced more than 2,000 tons in a single year.

Crystalline magnesite occurs in limestone in the Manchuria mountains, and is mined at Daisetsukyo for refractory purposes.

Magnesite is reported in Asiatic Turkey about 75 kilometers from Smyrna.

Australia.

—The deposits of magnesite in Queensland are so small that they probably have no commercial value. Rounded blocks of pure white magnesite outcrop in one locality in New South Wales, where many thousands of tons are available at small cost. An analysis shows 99.01 per cent. magnesium carbonate and no lime. Large deposits of magnesite are reported in South Australia. Extensive deposits also occur on the north end of the west coast of New Caledonia. A small quantity has been exported.