Pegmatite 1
Pegmatite 1 : An igneous rock with very large (usually > one inch), well-formed crystals. A granitic pegmatite has the mineralogy of a granite and abnormally large grains, whereas a gabbroic pegmatite has the mineralogy of a gabbro and very large grains. An intrusive igneous rock. (Plank and Schenck, 1998)