igneous
Pegmatite
Igneous Pegmatite
Composed mainly of coarse-grained quartz, feldspar, and mica crystals. Mohs hardness varies from 6 to 7 for quartz/feldspar components, color ranges from off-white and pink to tan with shiny mica flakes, vitreous to pearly luster, and blocky or tabular crystal structures.
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Physical properties
Composed mainly of coarse-grained quartz, feldspar, and mica crystals. Mohs hardness varies from 6 to 7 for quartz/feldspar components, color ranges from off-white and pink to tan with shiny mica flakes, vitreous to pearly luster, and blocky or tabular crystal structures.
Formation & geological history
Formed from the water-rich, late-stage crystallization of magma deep within the Earth's crust, allowing exceptionally large crystals to grow.
Uses & applications
Source of rare-earth elements, gemstones (like tourmaline, beryl, and topaz), and industrial minerals like lithium and feldspar.
Geological facts
Pegmatites are famous for hosting some of the largest individual crystals ever found on Earth, sometimes measuring several meters in length.
Field identification & locations
Easily identified by its extremely coarse-grained texture (phaneritic) with visibly large interlocking crystals, often found in ancient shield areas and mountainous orogenic belts.
