igneous
Pegmatite
Pegmatite (felsic intrusive igneous rock)
Hardness varies by mineral component (typically 6-7 on Mohs scale for quartz and feldspar), colors range from pink, red, white, and gray with dark patches of biotite or tourmaline, vitreous to dull luster, coarse-grained with exceptionally large crystals (often greater than 2.5 cm)
Identified More igneous →
Explore Pegmatite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness varies by mineral component (typically 6-7 on Mohs scale for quartz and feldspar), colors range from pink, red, white, and gray with dark patches of biotite or tourmaline, vitreous to dull luster, coarse-grained with exceptionally large crystals (often greater than 2.5 cm)
Formation & geological history
Formed from the water-rich, volatile-rich residual melt at the late stages of magmatic crystallization, allowing massive crystal growth.
Uses & applications
Source of rare-earth elements, lithium minerals, gemstones (like tourmaline, beryl, and topaz), and industrial minerals like quartz and feldspar.
Geological facts
Pegmatites can host some of the largest individual crystals ever found on Earth, sometimes measuring several meters in length.
Field identification & locations
Easily identifiable in the field by its extremely coarse-grained texture (phaneritic with giant crystals), often appearing as dikes cutting through other country rocks.
