EMERALD

a variety of beryl, a well-known gem of pure green colour, somewhat harder than quartz; specific gravity, 2:67 to 2-73. It is a silicate of aluminium and the rare element glucinum or beryllium, which was detected in it by Vauquelin after it had been discovered by the same chemist in the beryl. Its colour is due to the presence of chromium, of which there may be 0:2 to 0:3 per cent present. Its natural form is either rounded or that of a short six-sided prism. It is one of the softest of the precious stones, but is not acted on by acids. Emeralds of large size and at the same time free from flaws are rare and more valuable than diamonds or rubies; the largest on record is said to haye been po e ed by the inhabitants of the valley of Manta in Peru when the Spaniards first arrived there. It was as big as an ostrich egg, and was worshipped as the mother of emeralds. The ancients, who valued them, especially for engraving, are said to have procured them from Ethiopia and Egypt. The finest are now obtained from Colombia. The Oriental emerald is @ Variety of the ruby, of a green colour, and is an extremely rare gem.