igneous
Pegmatite
Granitic pegmatite, composed chiefly of quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, irregular interlocking crystals; pale pink to cream feldspar, glassy gray quartz, and dark mica are visible. Mohs hardness is roughly 6–7 overall; individual minerals have distinct hardness and cleavage.
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Physical properties
Coarse-grained, irregular interlocking crystals; pale pink to cream feldspar, glassy gray quartz, and dark mica are visible. Mohs hardness is roughly 6–7 overall; individual minerals have distinct hardness and cleavage.
Formation & geological history
Crystallized slowly from water-rich residual magma, commonly in veins and dikes associated with granite. Its age depends on locality and cannot be determined from the image.
Uses & applications
Used as a decorative and dimension stone; pegmatites are important sources of feldspar, mica, quartz, and sometimes lithium, gemstones, and rare elements.
Geological facts
The exceptionally large crystals typical of pegmatite form as volatile-rich magma allows ions to move and grow freely.
Field identification & locations
Look for conspicuously large, interlocking quartz and feldspar crystals, often with mica flakes. Common in granite-bearing regions worldwide; the specimen’s exact locality is unknown.
