PRINCIPAL SOUTH AFRICAN MINES 293
of clay having been sufficient until lately to more than offset the greater proportion of bort which is found in it.
The
Kimberley is a true volcanic chimney or pipe and the contents carry
diamonds throughout. When discovered, volcanic pipes of diamondiferous
material were unrecognized. The surface was staked out in claims and
worked as a very rich alluvial deposit, until it was discovered that
the supposed deposit was a circumscribed area within well-defined
limits, and the bed rock on which it rested was simply an unoxidized
continuation of the same material to an unknown depth.
There
were 470 full claims on this pipe, which at one time were split up
among 1,600 owners, but which later fell year by year into fewer hands,
and finally became absorbed into the De Beers Consolidation in 1889, as
described elsewhere.
What
the output of this mine was, in the early days of individual claims, is
unknown. It has always been comparatively large, but different parts of
the chimney have varied greatly, not only in the quantity of diamonds
contained in the earth, but in the character of them also. Some spots
have been very rich, others poor. In the west end the crystals are
perfect octahedrons or white glassy stones; elsewhere they are rounded
or the edges are beveled. In the southeast section, the diamonds have
shown a color tendency resembling those of the Dutoits-pan. The north
and northwest section of it, held many smoky stones, bort and broken
crystals, many of them mere fragments. Owing to the number of owners,
the great amount of stealing that went on, and an entire
