over
300 miles is totally unexplored. In the southern Urals, recent reports
state that rich deposits of platinum have been discovered in the
districts of Ougry and Katchkomury; but a great extension of the
platinum-producing area in this region is not to be expected, as the
ground has already been thoroughly prospected.
OTHER COUNTRIES.
Besides
the countries already mentioned as producing platinum, the metal has
been found in small quantities in Brazil, in the province of Minas
Geraes; in Spain, near Seville; in New South Wales, and in Burma,
Japan, Borneo, New Zealand, Tasmania, Sumatra, Honduras, Ecuador, and
French Guiana.
Platinum is being obtained in commercial quantities from the Hootalinqua River, Northwest Territory, Canada.
A
discovery of platinum in Madagascar has been reported. The metal is
said to occur in considerable quantities in the gold-bearing gravels of
the River Isonjo, in the province of Farafangana.
In
Mexico, small quantities of platinum have recently been obtained in the
municipality of Acapulco and the district of Tabares, Guerrero. The
metal is also reported as existing in the State of Vera Cruz, in the
district of Chocontepec, and at a few other localities in Mexico.
METHODS OF EXTRACTION. RUSSIA.
In
describing the various methods used for the mining and recovery of
platinum, those employed in Russia will first be considered, as it is
in this country that the greatest quantity of the metal is produced.
Then, too, in Russia, the extraction of the platinum is the first and
often the sole object of the miner, while in other countries the
platinum is generally of secondary consideration, and it is recovered
as a by-product of gold washing. The platinum-bearing gravels mined in
Russia possess all the characteristics common to the ordinary gold
placer. The "pay streak" varies in thickness from 10 to 100 inches, and
is generally covered with an overburden of barren gravels from 5 to 50
feet in depth. In cases where the thickness of the overlying gravel is
not too great, open mining is done, and all the material extracted is
treated; but the usual method is to sink shallow shafts to bed rock and
then drift along the pay streaks. There are said to be hundreds of
miles of these old drifts and tunnels on the Demidoff estate alone, so
that the extent to which this method of mining is practiced may well be
imagined.
The
bed rock is generally excavated for a depth of from 7 to 14 inches, and
the lower part of the overburden is also mined. As in most northern
latitudes where placer ground is worked in this way, the shaft sinking
and excavation of material takes place during the winter months, and
the extracted material is washed in the following summer. The material
to be treated is carted in wagons, which contain about 1,500 pounds, to
the washing plant, where the load is pulled up an incline to an
elevated platform from which it is fed with water into conical trommels
directly beneath. The oversize from these screens is thrown away, and
the undersize is sluiced, and the sluice concentrates panned in small
handpans called "kofchik."
The
sluices used are of peculiar construction and have two compartments.
The greater part of the metal settles in the first of these and the
remaining material then flows into the second compartment, where it is
puddled and raked (the stirring being done by women), and more of the
platinum is allowed to settle out. After this treatment the material
passes into a tailing sluice, whose riffles catch any heavy sand which
has escaped the compartments. This sand is liable to contain
considerable quantities of platinum, and is cleaned up by hand panning,
as are also the concentrates obtained in the two compartments.
