igneous
Quartz-rich pegmatite with green mica or chlorite
Granitic pegmatite; chiefly quartz (SiO₂), with feldspar and probable muscovite/chlorite
AI-generated identification · may be incorrectCoarse, interlocking crystals; white translucent quartz and pale feldspar with a silvery to green, platy or flaky mineral. Quartz hardness 7, feldspar 6–6.5, mica/chlorite about 2–3; vitreous to pearly luster and poor-to-perfect cleavage in mica.
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Physical properties
Coarse, interlocking crystals; white translucent quartz and pale feldspar with a silvery to green, platy or flaky mineral. Quartz hardness 7, feldspar 6–6.5, mica/chlorite about 2–3; vitreous to pearly luster and poor-to-perfect cleavage in mica.
Formation & geological history
Formed when silica- and water-rich magma cooled slowly in a late-stage vein, allowing exceptionally large crystals to grow. Pegmatites are generally Precambrian to Phanerozoic and occur in or near granitic intrusions.
Uses & applications
Used as a source of quartz, feldspar, mica, lithium, and rare metals; attractive pieces are collected, though this specimen appears mainly educational rather than gem quality.
Geological facts
The green material may be chlorite replacing biotite or green muscovite; exact identification requires a close-up, hardness, cleavage, or chemical testing.
Field identification & locations
Look for very coarse crystals, quartz-feldspar intergrowths, and mica flakes along fractures. Common in granitic terrains worldwide, including Maine, California, Brazil, Madagascar, and Norway.
