igneous
Weathered quartz-rich rock, possibly granite or gneiss
Granite-like aggregate: quartz (SiO₂), feldspar, and minor dark minerals
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled gray, white, and brown with a dull to slightly glassy luster. The small specimen appears granular and lacks visible cleavage, though its surface is weathered and identification is limited by the image.
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Physical properties
Hardness about 6–7 Mohs; mottled gray, white, and brown with a dull to slightly glassy luster. The small specimen appears granular and lacks visible cleavage, though its surface is weathered and identification is limited by the image.
Formation & geological history
Likely formed by slow crystallization of silica-rich magma, or recrystallization in a metamorphic equivalent, millions to billions of years ago; brown coloration may reflect iron-oxide weathering.
Uses & applications
Common granite is used as crushed stone, aggregate, building stone, countertops, and monuments; this small piece has mainly educational or collector value.
Geological facts
Quartz grains resist weathering and commonly remain raised or sparkly on broken surfaces, while feldspar alters to clay and iron-bearing minerals stain brown.
Field identification & locations
Look for interlocking visible grains, quartz that does not scratch with a steel knife, and feldspar cleavage; acid testing and a fresh fracture help distinguish granite from similar gneiss or quartzite. Common worldwide in continental crust.
