Intrusive Igneous Rock - Pegmatite
By Alec Augustine
Most pegmatites have a composition that is similar to granite with abundant quartz, feldspar, and mica.
Some of the world’s best tourmaline, aquamarine and topaz deposits have been found in pegmatites.
Uses and How & Where is is Formed
It forms near the margins of a magma chamber during the final phases of magma chamber crystallization.