Note 55 — MINERALS.
Reading edition
The Oriental Amethyst is an extremely rare gem, usually of purple colour, apparently formed by an union of the colouring matter of the sapphire and the ruby. This stone, if heated, loses its colour, and becomes transparent. After this process its brilliancy is such that it is scarcely distinguishable from the diamond; and, in jeweller’s work, it is occasionally substituted for that gem. The common amethyst (79), or that which is chiefly seen, is nothing more than a violet-coloured rock crystal (78).