igneous
Coarse-grained granite or granitic gneiss
Granite; chiefly quartz (SiO₂), feldspar, and mica/amphibole
AI-generated identification · may be incorrectGray, white, and dark mineral grains with a rough, crystalline texture and vitreous-to-dull luster. Typical granite hardness is about Mohs 6–7; grains are interlocking, with no obvious cleavage at the whole-rock scale.
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Physical properties
Gray, white, and dark mineral grains with a rough, crystalline texture and vitreous-to-dull luster. Typical granite hardness is about Mohs 6–7; grains are interlocking, with no obvious cleavage at the whole-rock scale.
Formation & geological history
Most consistent with slowly cooled intrusive felsic magma, forming plutonic rock millions to billions of years ago; faint mineral alignment could indicate gneissic metamorphism, which cannot be confirmed from the image.
Uses & applications
Used as crushed aggregate, road stone, building stone, monuments, and countertops; attractive polished pieces may be collected but this specimen appears ordinary.
Geological facts
The light grains are likely quartz and feldspar, while darker grains are probably biotite mica or amphibole. Granite commonly shows visible crystals because underground cooling is slow.
Field identification & locations
Identify by its visible interlocking quartz, feldspar, and dark mineral grains; quartz is typically glassy and gray, feldspar opaque white or pink, and mica may split into thin flakes. Common worldwide in continental crust and exposed plutons.
