Iceland crystal

Crystal Crys"tal (kr[i^]s"tal), n. [OE. cristal, F. cristal, L. crystallum crystal, ice, fr. Gr. kry`stallos, fr. kry`os icy cold, frost; cf. AS. crystalla, fr. L. crystallum; prob. akin to E. crust. See {Crust}, {Raw}.] 1. (Chem. & Min.) The regular form which a substance tends to assume in solidifying, through the inherent power of cohesive attraction. It is bounded by plane surfaces, symmetrically arranged, and each species of crystal has fixed axial ratios. See {Crystallization}. [1913 Webster]

2. The material of quartz, in crystallization transparent or nearly so, and either colorless or slightly tinged with gray, or the like; -- called also {rock crystal}. Ornamental vessels are made of it. Cf. {Smoky quartz}, {Pebble}; also {Brazilian pebble}, under {Brazilian}. [1913 Webster]

3. A species of glass, more perfect in its composition and manufacture than common glass, and often cut into ornamental forms. See {Flint glass}. [1913 Webster]

4. The glass over the dial of a watch case. [1913 Webster]

5. Anything resembling crystal, as clear water, etc. [1913 Webster]

The blue crystal of the seas. --Byron. [1913 Webster]

{Blood crystal}. See under {Blood}.

{Compound crystal}. See under {Compound}.

{Iceland crystal}, a transparent variety of calcite, or crystallized calcium carbonate, brought from Iceland, and used in certain optical instruments, as the polariscope.

{Rock crystal}, or {Mountain crystal}, any transparent crystal of quartz, particularly of limpid or colorless quartz. [1913 Webster]