Chapter XXI: Magnesite

BY R. W. STONE

USES OF MAGNESITE

Magnesite and its derived products are used in a variety of industries, the most essential of which, beyond doubt, is metallurgy. Owing to the high fusion point and chemical inertness of the oxide of magnesium, magnesite is one of the principal minerals used in the metallurgical and other industries where highly refractory material is required. For this purpose dead-burned magnesite is used in the form of brick or of grains. Brick and shapes are employed for lining open-hearth steel furnaces, welding, heating, and melting furnaces, reverberatories, settlers, and furnaces for refining lead, copper converters, and electrical furnaces. Crushed or granular magnesite is used for lining the bottoms of open-hearth steel furnaces, and in making crucibles and cupels.

In the manufacture of the cement known as oxychloride or Sorel cement the quantity of magnesite used is exceeded only by that used for refractory purposes. This cement is employed largely for sanitary flooring, and to a less extent for wall plaster, both interior and exterior. It is used also instead of Portland cement for some forms of exterior construction where quick and strong set is required. Magnesite is used in the manufacture of wood-pulp paper on the Pacific Coast, in fire-resisting paint, 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.

GEOLOGICAL OCCURRENCE

Deposits of magnesite are widely distributed throughout the world and occur in two distinct forms, amorphous and crystalline. Amorphous magnesite, the most common form, is fine-grained, and compact; it is usually found in veins or masses in serpentine resulting from the alteration of magnesia-rich rocks of the peridotite family. To this group belong the Grecian deposits, nearly all the California deposits, and those in Mexico, Venezuela, and other parts of the world. Crystalline magnesite is medium to coarse grained, and occurs as masses in limestone, dolomite or associated sediments which have been metamorphosed. The principal deposits of this class are those in Austria, Hungary, Quebec, and Washington.

Deposits of magnesite are regarded as having originated in three ways. The massive non-crystalline variety, such as that in California and Greece, is believed to have been formed by the decomposition of serpentine. Magnesite deposits near Bissel, California, and on Muddy River, near St. Thomas, Nevada, are said to be of sedimentary origin. The Austro-Hungarian, Washington, and Quebec deposits are regarded as resulting from the replacement of calcareous sedimentary rocks by magnesian-bearing solutions.

Magnesite deposits that occur as veins in connection with serpentinized magnesian rocks probably are formed both from the breaking down of the serpentine-making minerals and from the serpentine itself. It seems probable that usually both serpentine and magnesite are formed in the process of decay of the original minerals in peridotite and the allied basic rocks, and that during the decay of the serpentine the formation of magnesite continues. In any case the magnesia or magnesian mineral is changed to carbonate, dissolved by percolating water charged with carbon dioxide, and precipitated in cracks and crevices as veins. When formed in this way the magnesite occurs in large and small veins, lenses, and stockwork, and its distribution and extent are erratic. It seems fair to assume that these deposits may extend to the limit of depth of easily circulating surface waters, which in favorable conditions may be several hundred feet. Faulting, on the other hand, is as likely to cut the veins off in depth as in length. Any estimate of available tonnage of magnesite in deposits of this type therefore is unwarranted in advance of development work.

Sedimentary deposits such as those of Bissel, California, and near St. Thomas, Nevada, are by their nature more regular in occurrence, and their tonnage can be estimated from the outcrop in natural exposures and prospects.

Replacement deposits like those in Washington and Quebec are not so regular as the sedimentary deposits, but are more regular than the veins, and tonnage estimates may be based on the surface exposure and an assumed depth of 50 to 100 feet.

GEOGRAPHICAL DISTRIBUTION

The known distribution of magnesite deposits is as follows:

_North America._
Canada: Quebec, British Columbia and elsewhere.
United States: California, Washington, Nevada.
Mexico: Lower California on Santa Margarita Island.

_South America._
Venezuela: Island of Margarita.

_Europe._
Austria, Hungary, Germany, Greece, Italy, Macedonia, Norway, Sweden,
Russia.

_Africa._
Transvaal, Rhodesia, Portuguese West Africa.

_Asia._
India, in Madras and Mysore.

_Australia._
Queensland, New South Wales, South Australia, Tasmania.

_Oceania._
New Caledonia.

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.

POLITICAL AND COMMERCIAL CONTROL

The magnesite deposits that play a notable part in the world’s economy are situated in Canada, United States, Austria-Hungary, and Greece.

_United States._--The principal magnesite deposits in the State of Washington are owned by the Northwest Magnesite Co., Spokane, Wash.; Valley Magnesite Co., Spokane, Wash.; and American Mineral Production Co., Chicago, Ill. The Northwest Magnesite Co. is the largest producer in the Washington field and probably has made the largest investment. The American Mineral Production Co. has a plant at Valley, Wash.; the Valley Magnesite Co. has a deposit near Valley, but is not operating it.

The principal producers of magnesite in California in the summer of 1918 were the Tulare Mining Co., with a mine near Porterville; Porterville Magnesite Co. of California, with mine at Porterville; Western Magnesite Development Co., with a mine at Red Mountain; and Frank R. Sweasy, working the White Rock mine, Pope Valley, Napa County.

_Austria._--The Veitscher Magnesite Co., of Vienna, and the Magnesite Co., Ltd., of Budapest, formed a combination or cartel, with the understanding or agreement that all the sales of magnesite outside of Austria and Hungary had to be made through Carl Spater & Co., a German firm in Coblenz, Germany. The firm of Carl Spater & Co. formerly owned the works of the Veitscher Magnesite Co., but sold out and obtained the perpetual selling agency when the stock company was formed. The Harbison-Walker Refractories Co., Pittsburgh, Penn., is said to have been the American representative of Spater & Co.

The Austro-American Magnesite Co., whose deposit and works at Radenthein, Austria, represent an investment of $1,800,000, is owned by Americans. The entire stock is absolutely controlled by the principal stockholders of the American Refractories Co., or was so controlled before the war. The Austro-American Magnesite Co., it is claimed, was doing virtually 95 per cent. of the magnesite business in England before the war, and about 65 to 70 per cent. of the business in the United States. This company has a capacity of 150,000 tons of calcined magnesite a year.

When it was found that Carl Spater & Co., who handle both magnesite and magnesite brick made by the Veitscher Magnesite Co. and the Magnesite Co., Ltd., would not sell magnesite to the English refractory brick makers, the Austro-American Magnesite Co. formed a selling company in England, called the Anglo-Austrian Magnesite Co., of Sheffield, England. The English company sold magnesite from the Austro-American Magnesite Co. works at Radenthein, Austria, to all the refractory brick manufacturers of England, and virtually took all the English trade from the Germans.

The General Magnesite Co., of Budapest, has a magnesite deposit and plant at Hizonvich (Hisnyoviz?), Hungary. The stock of this company is believed to be owned principally by stockholders of the General Refractories Co., 111 Broadway, New York. The balance of the stock, believed to be about 40 per cent., is owned by some Hungarians of Budapest, represented by Mr. Gunst, of Budapest, president of the company.

According to the United States Department of Commerce,[154] there are seven companies exploiting magnesite in Greece: The Anglo-Greek Magnesite Co., Ltd., with head offices in London, England; the Société Financière de Grèce, Solon and Lycabettus Streets, Athens; The Internationale Magnesite Werken, with head offices in Rotterdam, Netherlands; L. Carambelas, Limni, Euboea; N. Papantonatos, Limni, Euboea; G. A. Georgidades, Athens, (exploiting a concession on behalf of the General Magnesite & Magnesia Co., of Philadelphia); and Alexiou, Daphnopotamos, Euboea. Most of the producers in 1917 had an abundance of orders for magnesite to be used in the steel industry in France and England.

[154] Commerce Reports, May 1, 1917.

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.