igneous
Pegmatite (Quartz and Feldspar with Dark Minerals)
Igneous Pegmatite
Hardness: 6-7 on Mohs scale (due to quartz and feldspar). Color: White, pink, and dark grey/black. Luster: Vitreous to pearly. Crystal structure: Phaneritic with extremely large crystals (pegmatitic texture). Cleavage: Present in feldspar components. Specific gravity: ~2.6 - 2.7
- Hardness
- 6-7 on Mohs scale (due to quartz and feldspar)
- Color
- White, pink, and dark grey/black
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale (due to quartz and feldspar). Color: White, pink, and dark grey/black. Luster: Vitreous to pearly. Crystal structure: Phaneritic with extremely large crystals (pegmatitic texture). Cleavage: Present in feldspar components. Specific gravity: ~2.6 - 2.7
Formation & geological history
Formed from the slow cooling of volatile-rich magma deep within the Earth's crust, typically during the final stages of magmatic crystallization, allowing massive crystal growth.
Uses & applications
Used as a source of industrial minerals, rare earth elements, gemstone mining (such as tourmaline, beryl, and spodumene), and occasionally as decorative stone.
Geological facts
Pegmatites are famous for containing some of the largest individual mineral crystals found on Earth, sometimes measuring many meters in length.
Field identification & locations
Identify in the field by its exceptionally coarse-grained texture, interlocking crystals of quartz and pink/white feldspar, and associated dark minerals like biotite or tourmaline. Common in continental shield areas and mountain-building belts.
