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CHAPTER VII.
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INDIAN DIAMONDS.
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LTHOUGH
the Diamond fields of India have been celebrated from remote antiquity,
it is only of late years, that our knowledge of Indian geology has been
sufficiently advanced to enable the mineralogist to speak with even
approximate accuracy as to the nature of the Diamond-bearing rocks of
that country. The materials accumulated by the Geological Survey have
been rendered accessible to the public, by the issue of an admirable "
Manual," of which the third volume is devoted to Economic Geology—a
subject which the late Prof. V. Ball, treated with great ability. A
fourth volume, by Mr. F. R. Mallet, forms a kind of supplement to this
work. The geological conditions under which the Diamond occurs in India
are fully dealt with in this official Manual.
The
Diamonds of India are generally found in superficial deposits derived
from the disintegration of the solid rocks. Where the Diamond
apparently occurs in situ, it is in certain rocks belonging to the great Vindhyan formation, a
formation which derives its name from the Vindhyan hills of the old
geographers, and which is of very great but unknown geological
antiquity. At the Panna mines, Diamonds have been found embedded in a
conglomerate belonging to a minor division of the Upper
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