Political and commercial geology and the world's mineral resources
Science
Political and commercial geology and the world's mineral resources
Geology, Economic; Mines and mineral resources
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.
Public-domain text, read in full here on John Shaqi.
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