Quartz, n.

(kwôrts, 108), n. [M. & N. H. Ger. quarz, Dan. qvarts, Sw. qvarts; Fr. quartz, It. quarzo, Sp. cuarzo.] (Min.) Pure silex, occurring in pellucid, glassy crystals, having the form of a six-sided prism, terminated at each end by a pyramid; and also in masses of various colors, more or less transparent, and sometimes opaque.

☞ Rose quartz is a rose-colored variety; amethyst, a violet; smoky quartz, a smoky-brown; chalcedony, an uncrystallized variety, nearly white, and waxy in luster; carnelian, a red or flesh-colored chalcedony; agate, a chalcedony in parallel or concentric layers of different colors; flint, a brown or black variety; jasper, an opaque, red, yellow, or brown quartz, colored by iron or ferruginous clay. Quartz is an essential constituent of granite, and abounds in rocks of all ages. Dana.