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African Diamonds. 91
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of
the second ; and 20 per cent, of the third ; the remainder being "
bort." The average value of rough Diamonds at a sale on the Fields is
as follows : " River," 65s. ', "Jar," 45s. ; "Du Toit's Pan," 28s. ; "Kimberley and De Beers," 21s. to 22s. 6d. ; " Bultfontein," 18s. 6d., and " Wesselton," 25s.
It
is said that Diamonds from the Leicester mine are mostly hard, white,
cross-grained stones, with an etched or frosted appearance ; whilst
those from the Newlands' Mines, lately discovered in Griqualand West,
are well-crystallized stones of remarkable whiteness.
All Diamonds which are too impure for cutting are now known under the general name of bort ; and
these possess a fixed market value, the powder which they yield when
crushed, being used for cutting and polishing Diamonds and other
stones, and in the engraving of gems of exceptional hardness.
Notwithstanding
the enormous number of Diamonds which have, been brought to light
during the recent workings in South Africa, it is notable that, so far
as the author knows, no Carbonado—the black, impure variety of
Diamond found in Brazil—has yet been discovered though the ilmenite, or
titaniferous iron-ore, sometimes passes improperly under the name of " carbon."
The following information is interesting as giving the latest results of working at the various Diamond Mines of South Africa :—
Produce of the De Beers Mine.—Out-put of Blue or Diamond-bearing Ground.—To end of June, 1897. The out-put for the year from this mine was 1,542,963 loads, of 16 cubit feet, which was mined
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