di Fassa, in the Tyrol, in Bohemia, in the island of Ceylon, and in many parts of South America ; and are called pleon'asto, from the Greek, which means very abundant.
The
zinciferous spinel, also called automalite or gahnite, is an alumina of
greenish or greyish zinc, generally opaque. Up to the present time it
has only been found in Switzerland, and near the city of Franklin, in
South America.
White spinel is procured from Mount Laziali.
Berzelius
asserts that when the spinel is heated, it first takes a dark tint,
then becomes black, afterÂwards opaque, but on cooling it changes
colour and becomes of a limpid green, from which it gradually returns
to its natural colour.
The
finest of the spinels is that which bears the additional name of ruby,
because red ; it is like the Oriental ruby, although its lively tint
tends a little to yellow, yet not so much as the jacinth and garnet.
Its chemical composition is
