—The largest deposits of manganese ore in South America are in Brazil, and especially in the important mining state of Minas Geraes.
In the Lafayette district in this state, manganese oxides occur in wide lenticular bodies, that seem to have no definite arrangement or association, except that most of them are bounded by schist or gneiss. The deposits lie in a complex of granite, gneiss, and crystalline schists; and the manganese oxides are probably derived from manganese-bearing carbonate and silicate minerals. The most productive area, known as the Morro da Mina, 2,500 feet long by 1,000 feet wide, contains four distinct bodies that range from 320 to 1,300 feet long and from 48 to 320 feet wide. Here manganese oxides persist 410 feet below the surface.
The area has yielded about 1,000,000 tons of ore and the reserves are probably between 7,000,000 and 10,000,000 tons.
In the same State of Minas Geraes, in the Miguel Burnier and Ouro Prieto districts, manganese oxides are interlayered with ferruginous sedimentary rocks of pre-Cambrian age.
In the State of Bahia, the Nazareth district contains bodies of manganese oxide in a thick surface zone of highly weathered schistose rocks. The oxides are probably derived from lenses of manganese garnet in schist. The largest deposit yielded 70,000 tons of ore. Manganese deposits are also reported near Bom Fim, in the same state.
Other deposits of manganese ore in Brazil are reported in the states of Maranhao and Matto Grosso.
The known manganese deposits of Minas Geraes lie within an area about 30 miles square, the center of which is about 300 miles north of Rio Janeiro. The ore is readily mined from open cuts, but existing transportation and loading facilities practically limit the annual exports to 550,000 tons.
Most of the important deposits in the Lafayette-Miguel Burnier and Ouro Prieto districts are owned by resident Brazilians. In 1915 a German company had worked a part of the Morro da Mina deposit for six or seven years and produced a total of 200,000 tons of ore. During 1915 a Belgian company was operating the Cocuruto mine near Ouro Prieto and was shipping 2,000 tons monthly. The largest deposit of the Nazareth district is owned by an American and the undeveloped deposits near Turyassu are owned by Norwegians.
From the beginning of the industry in 1894 to 1918, 4,660,000 tons of manganese ore were exported from Brazil. From 1900 to 1913, the annual exports ranged from 99,000 to 250,000 tons, but with the elimination of Russian sources in 1914, exports rose to 503,130 tons in 1916, 532,855 tons in 1917, and 393,388 tons in 1918. In October, 1917, the export tax on manganese ore was advanced from $0.85 to $3.00 per metric ton. Even before the war a large part of the Brazilian exports went to the United States. The destination of the 1913 exports was as follows: United States, 60 per cent.; Germany, 18 per cent.; Great Britain, 16 per cent.; France, 6 per cent.
In Chile, manganese ores occur at Corral Quemada, and nearby districts in the State of Coquimbo. In these districts, beds of manganese oxides are interlayered with sandstone, shale, and volcanic flows. Manganese is also found in the Carrizal district in the State of Atacama, where beds of manganese oxides are interbanded with shale and limestone. From 1885, when explorations were begun, to 1905, the exports of manganese ores from Chilean ports amounted to 549,716 tons, the maximum exports for one year being 50,871 tons, in 1892.