Aplite

A light-coloured, igneous rock characterized by a medium-grained (usually 0.1-2 mm) saccharoidal (i.e., aplitic) texture. Aplites may range in composition from granitic to gabbroic, but the term aplite with no modifier is generally understood to mean granitic aplite or aplitic granite, consisting essentially of quartz, potassium feldspar, and sodic plagioclase.