"Opal" is a word in ENGLISH

A semipellucid, uncrystallized variety of quartz, presenting various tints in the same specimen. Its colors are delicately arranged in stripes …

A variety of crystallized quartz, of a purple or bluish violet color, of different shades. It is much used as …

A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of …

A variety of translucent quartz, spangled throughout with scales of yellow mica.

Consisting of two pyramids placed base to base; having a pyramid at each of the extremities of a prism, as …

An opaque or milk-white chalcedony, a variety of quartz; also, a similar variety of opal.

A yellow or smoky brown variety of rock crystal, or crystallized quartz, found esp, in the mountain of Cairngorm, in …

A composite stone (quartz, schorl, and hornblende) in the walls of tin and copper lodes.

A variety of quartz or chalcedony, exhibiting opalescent reflections from within, like the eye of a cat. The name is …

A cryptocrystalline, translucent variety of quartz, having usually a whitish color, and a luster nearly like wax.

An impure, massive, flintlike quartz or hornstone, of a dull color.

A yellow, pellucid variety of quartz.

A mineral occuring in silky fibers of a lavender blue color. It is related to hornblende and is essentially a …

To reduce to fine particles by pounding or grinding; to comminute; as, to crush quartz.

The material of quartz, in crystallization transparent or nearly so, and either colorless or slightly tinged with gray, or the …

Imperfectly crystallized; as, granite is only crystalline, while quartz crystal is perfectly crystallized.

One of the ultimate parts which are variously combined in anything; as, letters are the elements of written language; hence, …

A crystal of one species inclosed within one of another, as one of rutile inclosed in quartz.

A finegrained rock, flintlike in fracture, consisting essentially of orthoclase feldspar with occasional grains of quartz.

A massive, somewhat impure variety of quartz, in color usually of a gray to brown or nearly black, breaking with …