\To"paz\, n. [OE. topas, F. topaze, L. topazos, or
topazion, a kind of precious stone, Gr. to`pazos, topa`zion;
possibly akin to Skr. tap to glow (cf. {Tepid}). According to
some, the name is from Topazos, a small island in the Red
Sea, where the Romans obtained a stone which they called by
this name, but which is the chrysolite of the moderns.]
1. (Min.) A mineral occurring in rhombic prisms, generally
   yellowish and pellucid, also colorless, and of greenesh,
   bluish, or brownish shades. It sometimes occurs massive
   and opaque. It is a fluosilicate of alumina, and is used
   as a gem.

2. (Zo["o]l.)Either one of two species of large, brilliantly
   colored humming birds of the {Topaza}, of South America
   and the West Indies.

Note: The two tail feathers next to the central ones are much
      longer that the rest, curved, and crossed. The Throat
      is metallic yellowish-green, with a tint like topaz in
      the center, the belly is bright crimson, the back
      bright red. Called also {topaz hummer}.

{False topaz}. (Min.) See the Note under {Quartz}.