pegmatite Meaning, Definition & Usage

noun a form of igneous rock consisting of extremely coarse granite resulting from the crystallization of magma rich in rare elements

From Gr. something fastened together, in allusion to the quartz and feldspar in graphic granite: cf. F. pegmatite. See Pegm.

(Min.) (a) Graphic granite. See under Granite. (b) More generally, a coarse granite occurring as vein material in other rocks.