26 A Book of Precious Stones
who transformed into stone a man, Diamond of Crete, for refusing to forget Jupiter after he had commanded all men to do so.
The
diamond is found in alluvial deposits of gravel, sand, or clay,
associated with quartz, gold, platinum, zircon, rutile, hematite,
ilmen-ite, chrysoberyl, topaz, corundum, garnet, and other minerals
appearing in granitic formations; also in quartzose conglomerates, in
peridotite veins, in gneiss, and in eruptive pegmatite.
The
ancient source of the world's supply of diamonds was exclusively India;
later Borneo produced some, but up to about the year 1700 India was the
sole source, and from the anciently famous diamond district and market
of Golconda, between Bombay and Madras, in the southern portion, came
the Kohinoor, the blue Hope Diamond, and other world-famous gems. The
French traveller Tavernier recorded that he visited Golconda in 1665
and that sixty thousand men were employed there; this field is now
abandoned. The modern diamond mines of India are in three principal
localities. The Madras Presidency in Southern India, which includes the
districts of Kadapah, Bellary, Kar-nul, Kistna, and Godavari, and also
ancient Golconda. The second locality is farther north
