igneous
Tumbled pegmatitic granite
Coarse-grained granite/pegmatite, chiefly quartz, feldspar, and biotite or amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled white, tan, gray, and dark brown-black, with a granular texture and vitreous to pearly luster. Interlocking quartz and feldspar crystals are visible; cleavage occurs mainly in feldspar and mica, not as a whole rock.
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Physical properties
Hardness about 6–7 Mohs; mottled white, tan, gray, and dark brown-black, with a granular texture and vitreous to pearly luster. Interlocking quartz and feldspar crystals are visible; cleavage occurs mainly in feldspar and mica, not as a whole rock.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma cooled slowly deep underground, allowing large crystals to grow; pegmatitic portions may form during the final stages of crystallization. Its exact geological age cannot be determined from the image and may range from Precambrian to younger intrusive bodies.
Uses & applications
Used as dimension stone, countertops, aggregate, landscaping material, and decorative tumbled specimens; generally limited jewelry value.
Geological facts
The pale translucent grains are likely quartz, while blockier cream-to-pink grains are feldspar and dark flakes may be biotite or amphibole. The rounded surface is human-tumbled or naturally water-worn.
Field identification & locations
Identify it by its coarse interlocking crystals, quartz translucency, feldspar cleavage, and lack of layering or fossils; common worldwide in granitic terrains. A hand lens and streak, hardness, and acid tests help distinguish it from quartzite or conglomerate.
