besides
its characteristic of an uneven and irregular distribution of colour,
it is unique geologically, for it occurs exclusively in its primary
situation, that is, in the rock in which it was formed. It is one of
the minerals characteristic of crystalline schists, and is frequently
found embedded in mica schists and similar rocks. The magnificent
beryls found at Muzo, Colombia, however, are an exception; there the
emeralds are embedded in calcite veins in limestone. Emeralds are
never found in gem gravels, like diamonds, rubies, sapphires, and other
precious stones.
The
ancient source of the emerald was Ethiopia, but the locality is
unknown. From upper Egypt, near the coast of the Red Sea and south of
Kosseir, came the first emeralds of historic commerce. There is a
supposition that the emerald beryl was first introduced commercially
into Europe just prior to the seventeenth century from South America.
Emeralds had been found before this, however, in the wrappings of
Egyptian mummies and in the ruins of Pompeii and Herculaneum. Ancient
Egyptian emerald mines on the west coast of the Red Sea were
rediscovered about 1820 by a French explorer, Cailliaud, on an
expedition organised by
