CANADA.
In Canada a large diamond was reported " found
in the Nipissing district, though the report has not been
authenticated. Attempts to trace the diamonds found in the glacial
drifts of Ohio, Indiana, Michigan, and Wisconsin back to their
original source have not so far been successful. Dr. Robert Bell,6
of the Canadian geological survey, considers the source of the
diamonds found in these States to be just north of Lake Superior, where
there is a volcanic area in which igneous rock and shales containing
carbonaceous matter are abundant. Debris from this area would have been
carried by the ice sheet in the same course as the jasper conglomerate
bowlders which are found with the diamonds and have come from the
extreme eastern part of the Lake Superior region. In the Muskoka
district, east of Georgian Bay, peridotite rocks cut shales carrying
carbonaceous matter, thus giving conditions similar to those in South
Africa.
SOUTH AFRICA.
De Beers Consolidated Mines.0—According
to the eighteenth annual report of the De Beers Consolidated Mines
operations during the year 1906 were pushed with increased activity.
The total production of blue ground at all the mines—De Beers and
Kimberley, Wesselton, Bultfontein, and Dutoitspan—was 8,144,979 loads,
as against 5,433,357 in 1905; and the total quantity washed was
5,625,592 loads, as against 5,128,015 in 1905. This leaves a remainder
of 6,769,126 loads on the floors, an increase of 2,519,387 during the
year. The average number of carats recovered per load was slightly
less for each of the mines than during the previous year, though this
was more than offset by the increased value of the diamonds per carat
and the greater number of loads washed. The increase in the number of
loads washed came chiefly from the Dutoitspan and the Bultfontein
mines, while the others treated less than during 1905. Correspondingly,
the increase in the total value of diamonds produced came chiefly from
the Dutoitspan and Bultfontein mines, with a smaller increase from the
Wesselton. An increased quantity of tailings and debris was treated
during the year, with a corresponding increase in the quantity and
value of diamonds obtained from such material. The quantity and value
of diamonds thus obtained, however, did not equal that from a smaller
quantity of tailings treated in 1904.
The
total amount of blue ground in sight for all the mines at the close of
the year was 64,315,580 loads, as against 59,326,700 loads in 1905.
This does not take into consideration the probable great depths to
which the mines can be profitably worked below the present lowest
levels. At the same rate of washing per year as in 1906 it would take
eleven years to exhaust the mines above their present lowest levels,
and with the same rate of yield and valuation there would be a product
worth £64,000,000.
The
five-year contract with the diamond syndicate expired at the close of
the year 1906, but was renewed for the same period of time on even more
advantageous terms. The market remained strong and the
