1. a very coarse-grained igneous rock composed mainly of quartz and feldspar, often containing rare minerals
Usage: geology

Examples

• The geologist discovered a pegmatite vein containing large crystals of tourmaline.
• Pegmatite formations are important sources of lithium and other rare elements.
• The museum displayed specimens of pegmatite with crystals over six inches long.
• Mining companies extract beryl and spodumene from pegmatite deposits.
• The pegmatite intrusion cut through the surrounding granite bedrock.
• Students examined the coarse texture of the pegmatite sample under magnification.