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THE BOOK OF DIAMONDS
It
is a mistake to speak of "river washings". The dia-mantiferous deposits
are not special to the old or recent river beds, but appear to be
alluvial deposits spread over a large tract of country by the agency of
water, which at some period of time subsequent to the filling up of the
volcanic pipes planed off and projected from the surface of the
country. Thus the debris was scattered broadcast over the land. The
larger diamonds and other heavy minerals would naturally seek the
lowest places, corresponding with the river bed, past and present.
At
Klipdorn near Kimberley the diamantiferous earth is remarkably like
river gravel, is of a strong red color—quite different from the
Kimberley blue ground—and forms a layer from one to eight feet thick.
The
surface of the country round Kimberley is covered with a ferruginous
(iron like) red, adhesive, sandy soil which makes horse traffic very
heavy. Below the red soil is a basalt, much decomposed and highly
ferruginous, from twenty to ninety feet thick, and lower still from two
hundred to two hundred and fifty feet of black slaty shale containing
carbon and iron pyrites. These are known as Kimberley shales; they are
very combustible, and in a part of DeBeer's Mine where they were
accidentally fired they smouldered for over eighteen months.
By
1889 mining below the bottom of the pits by means of shafts and
underground tunnels had been commenced. Modern methods date from this
time when Cecil Rhodes and Alfred Beit secured control of the DeBeer
company.
The scene of native mining was now transferred from
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