igneous
Granite Pegmatite
Pegmatite (Quartz, Feldspar, Mica)
Hardness of 6-7 on the Mohs scale, mixed colors including clear quartz, white/pink feldspar, and dark biotite mica flakes, vitreous to pearly luster, interlocking crystal structure, specific gravity around 2.5-2.7.
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Physical properties
Hardness of 6-7 on the Mohs scale, mixed colors including clear quartz, white/pink feldspar, and dark biotite mica flakes, vitreous to pearly luster, interlocking crystal structure, specific gravity around 2.5-2.7.
Formation & geological history
Formed from the slow cooling of extremely water-rich magma deep within the Earth's crust, allowing very large crystals to grow. Typically associated with the late stages of igneous pluton crystallization.
Uses & applications
Source of industrial minerals such as quartz, feldspar for ceramics, mica, and rare earth elements or gemstone crystals like tourmaline and beryl.
Geological facts
Pegmatites can host some of the largest individual mineral crystals ever found on Earth, sometimes measuring several meters in length.
Field identification & locations
Easily identified by its exceptionally coarse-grained texture with visible, large interlocking crystals of quartz and feldspar, commonly found near large granitic intrusions worldwide.
