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806
MINERAL RESOURCES.
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Vaal River diamonds.—The
terraces and river gravels along the Vaal River from Bloemhof, in
Transvaal, to its junction with the Orange River in Griqualand West, a
distance of about 200 miles, have been worked for diamonds.0
The deposits vary from a few inches to 40 or 50 feet in thickness, and
in some cases extend 3 or 4 miles laterally from the river. The gravels
consist of a large number of greenstone bowlders filled in with sand
and pebbles, and resting on a flow of amygdaloidal greenstone. The
pebbles are chiefly siliceous, as jasper, chalcedony, agate, etc., and
with them are associated pebbles of greenstone, ironstone, ilmenite,
garnet, topaz, and diamond. There has been more than one period of
sedimentation, and the gravels of the most recent period have a matrix
of stiff siliceous clay. The diamonds have been found almost everywhere
through the gravel deposits, there being no reliable geological
indications as to their occurrence. The placer diamonds, taken
collectively, are probably the finest stones obtainable in South
Africa. They occur more commonly in dodecahedral crystals and are
singularly free from flaws. Stones with a yellowish tint are
predominant, though all colors are found. The value is estimated at
about £6 per carat for all diamonds sold to buyers along the river.
SOUTH AMERICA.
Brazil.—The
diamond and carbon mining industry of Brazil is increasing.
Consul-General George E. Anderson, of Rio de Janeiro, reports that
dredges6 have been installed along the Jequitinhonha River,
in the State of Minas Geraes, and that large amounts of American
capital are being invested in the Diamantina country. The work on the
mines in the latter region has necessitated the building of a highway
from the end of the railroad at Curalinho. This work is under the
direction of an American engineer and will be carried out by American
methods. Heretofore the shipments of Brazilian diamonds have been to
Europe, though it is likely a number of them will be made to this
country direct, now that American capital is so heavily interested.
It
is difficult to obtain information on the production of Brazilian
diamonds, since large quantities were smuggled out of the country to
avoid the payment of the 5 per cent export tax. Consul-General
Anderson, in the report quoted above, gives the value of diamonds
registered for export during 1906 as $310,000. This is said to include
the carbons or black diamonds from Bahia. That the official export
figures do not adequately represent value of the production is shown by
the figures given in a report by former Vice-Consul J. P.W. Rowe,c of
Bahia, in which it is estimated the annual exports from that State
amount to over $4,000,000. The State government of Bahia found that it
failed to receive the proper revenue due from the 7 per cent export
tax, and accordingly abolished the export-tax law in favor of another.
Each merchant or dealer shipping diamonds or carbons was to be charged
an amount calculated to bring the revenue up to what it should have
been under the 7 per cent export-tax law. The new law was met by the
combining of many dealers and their shipping as one firm.
»
Park, Mungo, Vaal River, South Africa, diamond fields: Mining Science,
March 19,1908. &U. S. Daily Cons. Repts., January 20, 1908. «U. S.
Daily Cons. Repts., January 7,1908.
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