igneous
Rounded granitoid pebble (likely granite or granodiorite)
Granite–granodiorite; chiefly quartz, feldspar, and dark mica/amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale cream-gray, speckled black, with a granular crystalline texture and glassy-to-dull luster. It has no obvious cleavage as a whole and appears water-worn and polished naturally.
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Physical properties
Hardness about 6–7 Mohs; pale cream-gray, speckled black, with a granular crystalline texture and glassy-to-dull luster. It has no obvious cleavage as a whole and appears water-worn and polished naturally.
Formation & geological history
An intrusive igneous rock crystallized slowly from magma deep in the crust, commonly hundreds of millions to billions of years old; the rounded shape formed by erosion and transport in streams or glacial deposits.
Uses & applications
Used as aggregate, building stone, countertops, monuments, and landscaping material; this small specimen has mainly educational or decorative value.
Geological facts
The dark grains are likely biotite mica or amphibole, while the light grains are feldspar and quartz. Exact identification would require a fresh surface, acid test, hand lens, and possibly thin-section or chemical analysis.
Field identification & locations
Look for interlocking visible grains, abundant pale feldspar, translucent quartz, and scattered dark minerals; granite is common worldwide, especially in continental mountain belts and glacial gravels. Estimated value: $1–$10 as a common pebble, or up to about $20 if unusually attractive or provenance-labeled.
