igneous
Pegmatitic granite fragment
Granitic pegmatite, chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse, interlocking crystals with white to pink feldspar, glassy gray quartz, and dark reflective mica; Mohs hardness about 6–7, vitreous to pearly luster, no consistent cleavage as a whole, specific gravity about 2.6–2.7.
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Physical properties
Coarse, interlocking crystals with white to pink feldspar, glassy gray quartz, and dark reflective mica; Mohs hardness about 6–7, vitreous to pearly luster, no consistent cleavage as a whole, specific gravity about 2.6–2.7.
Formation & geological history
Formed when silica-rich magma crystallized slowly, commonly in a late-stage pegmatite vein; typically Precambrian to younger, depending on locality.
Uses & applications
Used as decorative stone, aggregate, and a source of feldspar, quartz, mica, and occasionally lithium, beryl, or tourmaline; attractive pieces are collected but usually have modest value.
Geological facts
The very large, easily visible crystals are characteristic of pegmatitic texture and indicate slow cooling with volatile-rich residual magma.
Field identification & locations
Identify by its coarse crystal size, pink/white feldspar, translucent quartz, and platy black or silvery mica; common in granitic terrains and pegmatite districts worldwide.
