Pegmatite Wikipedia
A pegmatite is an igneous rock formed by slow crystallization at high temperature and pressure at depth and exhibiting large interlocking crystals usually greater in size than cm Most pegmatites are intrusive rocks found in sheets of rock near large masses of igneous rocks called batholiths The word pegmatite derives from Homeric Greek πήγνυμι which means to bind together in reference to the intertwined crystals of quartz and feldspar in