Diamonds is also composed of the cemented detritus of other rocks.
But
at Wajra Karur, near Bellary, in north lat. 15° and east long. 77°,
where the Diamonds are often found lying loose on the surface after a
rain, a much more interesting and instructive mode of occurrence is
recorded. Chaper, (" Comptes Bendus," vol. xcviii., 1884), a French
traveller, states that he himself found two Diamonds in this
neighbourhood in 1882, in some of the pegmatite veins, with Epidote,
traversing the gneiss which underlies the soil here. The Diamonds were
associated with Buby and Sapphire. It has been suggested that Chaper
was deceived by his native attendant, and that the associated Corundum
showed signs of workmanship. As Max Bauer points out, the association
of Diamond with Corundum and Epidote, is met with elsewhere in India,
and the detrital rocks in which the mineral occurs in these other
localities may possibly have originated from the disintegration of a
rock similar to the gneiss of Wajra Karur. To the west of this town a
pipe of material similar to the agglomerate of Ivimberley was found,
but it yielded no Diamonds. Still, many similar pipes in South Africa
have shown no signs of this gem.
Some
400 miles to the north-east of the Kollur group of mines there are
found many deposits in the Mahanadi river, chiefly in its upper part.
This river has been by some identified with the river mentioned by
Ptolemy. The Mahanadi deposits occur in the sand and gravel brought
down by the river, so the only light thrown on the origin of the
mineral is what is derived from a consideration of the associated
minerals. These, besides Quartz and some
