igneous
Pegmatite
Igneous Pegmatite (Quartz-Feldspar-Biotite)
AI-generated identification · may be incorrectHardness varies from 6 to 7 on the Mohs scale. Displays a very coarse-grained texture with white quartz, tan feldspar, and dark biotite crystals.
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Physical properties
Hardness varies from 6 to 7 on the Mohs scale. Displays a very coarse-grained texture with white quartz, tan feldspar, and dark biotite crystals.
Formation & geological history
Formed from the water-rich, final stage of magma crystallization deep within the Earth's crust, typically during mountain-building events.
Uses & applications
Source of rare earth elements, gemstones, and industrial minerals like lithium, mica, and high-purity quartz.
Geological facts
Pegmatites can host gargantuan crystal specimens, sometimes growing many meters in length. They are the primary source for gem-quality tourmaline and beryl.
Field identification & locations
Identified by its exceptionally large, interlocking crystals compared to surrounding finer-grained rocks. Commonly found in ancient continental shields and orogenic belts.
