igneous
Polished granitic pebble
Granite, composed chiefly of quartz, feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse, mottled white, gray, black, and brown grains with vitreous to dull luster; interlocking crystals, no obvious cleavage as a whole, Mohs hardness about 6–7, and specific gravity around 2.6–2.8.
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Physical properties
Coarse, mottled white, gray, black, and brown grains with vitreous to dull luster; interlocking crystals, no obvious cleavage as a whole, Mohs hardness about 6–7, and specific gravity around 2.6–2.8.
Formation & geological history
A felsic intrusive igneous rock formed by slow cooling of silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic mountain-building events; the rounded shape is likely from stream or glacial abrasion and polishing.
Uses & applications
Used extensively for countertops, monuments, paving, building stone, aggregate, and landscaping; this small polished piece is mainly decorative or suitable for a teaching/collection specimen.
Geological facts
The brown areas may be iron-oxide staining or weathered feldspar, while dark patches likely contain biotite, hornblende, or mafic inclusions.
Field identification & locations
Identify it by visible interlocking light quartz/feldspar and dark mica or amphibole grains, unlike sedimentary rocks’ layers or metamorphic foliation; common worldwide, especially in continental shields and mountain belts.
