igneous
Pegmatitic granite (quartz–feldspar–mica rock)
Granitic pegmatite; chiefly quartz (SiO₂), potassium feldspar and plagioclase, with dark mica such as biotite
AI-generated identification · may be incorrectCoarse, irregular interlocking crystals with pink/cream feldspar, gray quartz, and dark mica; minerals are typically Mohs 6–7, vitreous to pearly, with feldspar cleavage and no true rock-wide crystal structure.
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Physical properties
Coarse, irregular interlocking crystals with pink/cream feldspar, gray quartz, and dark mica; minerals are typically Mohs 6–7, vitreous to pearly, with feldspar cleavage and no true rock-wide crystal structure.
Formation & geological history
Likely formed as a slowly cooled, silica-rich residual melt in veins or pockets within granite, producing large crystals; pegmatites are commonly Precambrian to younger, depending on the host intrusion.
Uses & applications
Pegmatite is quarried for feldspar, quartz, mica, and sometimes lithium or rare-element minerals; attractive pieces are used as decorative stone and collected as specimens.
Geological facts
Pegmatites can host unusually large crystals and economically important lithium, tantalum, and beryllium minerals; none is clearly identifiable in this specimen.
Field identification & locations
The coarse mix of pale feldspar, glassy-looking quartz, and dark mica suggests pegmatitic granite, though a photo cannot confirm the minerals. Found in granitic regions worldwide; typical rough hand specimens sell for about $5–$30 USD.
