and
covers the stratum of diamondiferous material at the bottom. The water
is carried up by a chain pump of bowls operated by hand, and the
diamond-bearing earth is hoisted in baskets by a pulley to the surface.
A hole in the wall of the pit near the bottom affords shelter for the
overseers set to watch the miners. When prase is found in abundance it
is regarded as a sure indication that the yield of diamonds will be
more than ordinarily good.
A
few miles northeast of Panna, the geological conditions are more
favorable for mining. The overlying stratum is a firm rock of Rewah
sandstone which permits considerable tunneling in the underlying
diamond-bearing stratum, from the bottom of the pits.
These
mines of the northern spur of the Panna group reaching toward Allahabad
are all at some depth, except those at the extreme eastern end of it,
where the diamond-bearing stratum is a sandstone conglomerate which
crops out to the surface. To the south are two waterfalls which carry
.diamondiferous material from the stratum situated above, to the valley
of the Baghin river below, where the diamonds are collected from the
sands.
There
is a mine southwest of Panna, abandoned some years ago, though it is
believed to contain many diamonds yet, which illustrates the first idea
the African diamond miners had of the chimneys there, before they
understood their volcanic nature. It lies in a great conical basin in
the sandstone, several hundred feet in diameter and about ioo feet
deep. The basin is partially filled with a green mud covered by a
deposit of calcareous tufa. It has been worked to about half the depth,
and it is claimed that the yield increases with the depth.
