Tourmaline
is like beryl, a mineral which is in itself of great interest,
especially to scientists, and one which in smaller crystals sometimes
attains such beauty of coloring and brilliancy as to become of rare
charm as a gem.
Tourmaline
has always puzzled scientific authorities in determining its
composition, and in lack of a concise or authoritative definition of
the chemicals composing it, we will quote the following description of
its composition given by Ruskin, in his "Ethics of the Dust": "A little
of everything, there's always flint and clay and magnesia in it; and
the black is iron according to its fancy; and there's boracic acid, if
you know what that is, and if you don't, I cannot tell you today, and
it doesn't signify, and there's potash and soda; and on the whole, the
chemistry of it is more like a medieval doctor's prescription than the
making of a respectable mineral."
As we noted at first, tourmaline as a mineral is quite distinct from its rarer gem species.