igneous
Pegmatitic granite (likely feldspar–quartz–mica rock)
Granitic pegmatite; chiefly K-feldspar and quartz, with mica and iron-oxide staining
AI-generated identification · may be incorrectCoarse, interlocking crystalline texture; white to cream feldspar and quartz with reddish-brown mica or oxidation. Hardness is approximately 6–7 Mohs, vitreous to pearly luster, no consistent cleavage as a whole, and specific gravity about 2.6–2.7.
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Physical properties
Coarse, interlocking crystalline texture; white to cream feldspar and quartz with reddish-brown mica or oxidation. Hardness is approximately 6–7 Mohs, vitreous to pearly luster, no consistent cleavage as a whole, and specific gravity about 2.6–2.7.
Formation & geological history
Forms when the final, water-rich melt in a granitic intrusion crystallizes slowly, producing unusually large crystals; commonly Precambrian to Phanerozoic in age. The reddish areas may reflect weathered biotite or iron oxides.
Uses & applications
Used locally as dimension stone, aggregate, and a source of feldspar, quartz, mica, and sometimes rare-element minerals; attractive pieces are collected but are generally not jewelry-grade.
Geological facts
Pegmatites can host tourmaline, beryl, garnet, lithium minerals, and large quartz or feldspar crystals. This rounded specimen may be naturally weathered or water-worn.
Field identification & locations
Identify by visible coarse crystals, abundant pale feldspar, glassy quartz, and possible flaky mica; a fresh surface and acid test can help distinguish it from carbonate rock. Common in granitic terrains worldwide.
