the only principle substituted, but then it is accompanied by an equivalent proportion of magnesia or oxide of manganese.
The beautiful variety of yellow garnet called pyrope belongs
to the almandine species. It differs only from the type by a little
quantity of the oxide of chromium taking the place of an equivalent
quantity of the other bases. This substitution is regarded as
perfectly regular by the mineralogist, but it produces a very agreeable
colour, and gives commercially an altogether peculiar value to the pyrope.
It is to the almandine species also that the garnets so well known in commerce as Bohemian garnets belong. They are furnished by Bohemia, Saxony, and other parts of Germany.
The
most desirable garnet is the oriental or Syrian garnet. Its composition
varies, but its lustre and beauty place it above all others. Its name
is not derived from Syria, as is often supposed, but from the Syrian,
a river in the country called Pegu in Asia. It was from that country,
indeed, that the first specimens were brought; but this commercial
species is found equally in the Isle of Ceylon and in Brazil.
