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A yellow, pellucid variety of quartz.

nd soda; -- called also blue asbestus. A silicified form, in which the fibers penetrating quartz are changed to oxide of iron, is the yellow brown tiger-eye of the jewelers.

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 like; - - called also rock crystal. Ornamental vessels are made of it. Cf. Smoky quartz, Pebble; also Brazilian pebble, under Brazilian.

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

rt in a machine; one of the essential ingredients of any mixture; a constituent part; as, quartz, feldspar, and mica are the elements of granite. The simplicity which is so large an element in a noble nature was laughed to scorn. Jowett (Thucyd.).

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

like 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 a conchoidal fracture and sharp edge. It is very hard, and strikes fire with steel.

The commonest color is red, the luster is vitreous, and the hardness greater than that of quartz. The dodecahedron and trapezohedron are the common forms.

A crystalline rock, consisting, like granite, of quartz, feldspar, and mica, but having these materials, especially the mica, arranged in planes, so that it breaks rather easily into coarse slabs or flags. Hornblende sometimes takes the place of the mica, and it is then called hornblendic or syenitic gneiss. Similar va…

shade off; as, sandstone which graduates into gneiss; carnelian sometimes graduates into quartz.

A crystalline, granular rock, consisting of quartz, feldspar, and mica, and usually of a whitish, grayish, or flesh-red color. It differs from gneiss in not having the mica in planes, and therefor in being destitute of a schistose structure.

A whitish, granular rock, consisting of feldspar and quartz intimately mixed; -- sometimes called whitestone, and leptynite.

A siliceous stone, a variety of quartz, closely resembling flint, but more brittle; -- called also chert.

An opaque, impure variety of quartz, of red, yellow, and other dull colors, breaking with a smooth surface. It admits of a high polish, and is used for vases, seals, snuff boxes, etc. When the colors are in stripes or bands, it is called striped or banded jasper. The Egyptian pebble is a brownish yellow jasper. Jasper…

rotating the plane of polarization towards the left; levogyrate, as levulose, left handed quartz crystals, etc. [Written also lævorotatory.]

A quartzose trachyte; rhyolite.

A dark variety of smoky quartz.

A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity.