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THE DIAMOND
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826
feet, were made and found to be all in diamondifer-ous ground, though
they also showed considerable waste and inclusive rock. Little water
was encountered, except at the juncture of the rim rock, where there
was considerable.
The
Premier was found to be a huge volcanic chimney of diamondiferous
earth similar to those of the Kimberley district, but very much larger.
It has since been found to cover an area equal to 3,571 mining claims
of 30 by 30 feet, or about eighty acres. Of this total claim area,
3,441 claims have been worked down to an average depth of eighty feet.
Unlike the Kimberley mines, it had no limestone capping, but under the
tufa-ceous top, the crater was covered with a red clayey surface soil
five or six feet thick. Under this lay about thirty feet of yellow
ground which gradually merged into the unoxidized blue peculiar to the
African diamond pipes. The blue of the Premier is much more friable
than that of the Kimberley mines, and therefore does not need
weathering as that of the other mines does, but goes direct to the
washing plant, thereby eliminating the expense and loss of time
resulting from spreading on floors. Below the sixty-foot level the blue
became very hard. It was found, however, by sinking shafts, that it was
a layer only, about eighty feet thick. Below it, the blue becomes soft
and friable again.
The
Premier mine is shaped like a pear. It is situated on a level plateau
at an elevation of about two hundred feet, and is surrounded by hills
and kopjes about a hundred feet high. The surrounding geological
formation differs somewhat from the Kimberley district. Some sandstone
outcrops, but diabase is the common
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