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Ferruginous quartz, of a blood-red or brownish red color, sometimes with a tinge of yellow.

The pulverized matter from a quartz mill, or the lighter soil of hydraulic mines. [Local, U. S.]

ial used in various arts. It is a vitreous substance made of cobalt, potash, and calcined quartz fused, and reduced to a powder.

Suspicious; open to suspicion. [Obs.] Foote. Smoky quartz (Min.), a variety of quartz crystal of a pale to dark smoky-brown color. See Quartz.

Orig., a rock composed of quartz, hornblende, and feldspar, anciently quarried at Syene, in Upper Egypt, and now called granite.

hexagonal system, bounded by six trapezoidal planes. The faces of this form are common on quartz crystals.

Pure silica, like quartz, but crystallizing in hexagonal tables. It is found in trachyte and similar rocks.

The nonmetalliferous mineral or rock material which accompanies the ores in a vein, as quartz, calcite, barite, fluor spar, etc.; -- called also veinstuff.

is) having a slender, black and shining stem and branches. -- Venus's hair stone (Min.), quartz penetrated by acicular crystals of rutile. -- Venus's looking-glass (Bot.), an annual plant of the genus Specularia allied to the bellflower; -- also called lady's looking- glass. -- Venus's navelwort (Bot.), any one of s…

A pigment obtained, usually by roasting cobalt glance with sand or quartz, as a dark earthy powder. It consists of crude cobalt oxide, or of an impure cobalt arseniate. It is used in porcelain painting, and in enameling pottery, to produce a blue color, and is often confounded with smalt, from which, however, it is dis…