Ruby
a term applied popularly to two distinct minerals—the pyrope and the spinelle ruby, both of which are much valued as gems. The pyrope is a silicate of magnesia and alumina, with varying admixtures of iron, chromium, manganese, and lime. It occurs chiefly at Zöblitz, in Saxony; at Mittelgebirge, in Bohemia; and at Elie, in Scotland. The spinelle ruby and its varieties, the orange-red rubicelle, and the violet or brown almandine, are aluminates of magnesia, with different proportions of iron and chromium. They mostly occur in Ceylon at mium. They mostly occur in Ceylon at Ava and in other parts of the East Indies. Rubies are wonderfully imitated.