igneous
Polished granite pebble
Granite, typically quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray-beige with black mica/hornblende and pinkish feldspar, granular texture, vitreous to dull luster, no consistent cleavage as a whole, and specific gravity about 2.6–2.7.
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Physical properties
Hardness about 6–7 Mohs; pale gray-beige with black mica/hornblende and pinkish feldspar, granular texture, vitreous to dull luster, no consistent cleavage as a whole, and specific gravity about 2.6–2.7.
Formation & geological history
Slowly cooled silica-rich magma crystallized deep underground, commonly during Precambrian to Phanerozoic continental crust formation; the rounded shape is likely from natural abrasion or tumbling.
Uses & applications
Used for aggregate, building stone, countertops, landscaping, and decorative polished pebbles; this small specimen has modest collecting value.
Geological facts
Visible interlocking grains and dark mineral flecks distinguish it from marble and many sedimentary rocks. Individual grains may include quartz, alkali/plagioclase feldspar, biotite, and amphibole.
Field identification & locations
Identify it by its coarse interlocking texture, lack of layering or fossils, hardness, and resistance to scratching by steel. Common worldwide in continental mountain belts and exposed basement terrains.
