igneous
Weathered granite
Granite, chiefly quartz, potassium feldspar, plagioclase, and biotite or hornblende
AI-generated identification · may be incorrectCoarse-grained, mottled tan, cream, and black; visible interlocking crystals, with no obvious cleavage. Hardness is about 6–7 Mohs; typically nonmetallic and dull to slightly glassy on fresh surfaces.
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Physical properties
Coarse-grained, mottled tan, cream, and black; visible interlocking crystals, with no obvious cleavage. Hardness is about 6–7 Mohs; typically nonmetallic and dull to slightly glassy on fresh surfaces.
Formation & geological history
Granite forms when silica-rich magma cools slowly underground, allowing large crystals to grow; specimens may be hundreds of millions to billions of years old.
Uses & applications
Used as dimension stone, paving, countertops, monuments, and aggregate; this small weathered piece is mainly suitable for collecting.
Geological facts
The dark patches likely represent mica or amphibole, while the lighter grains are feldspar and quartz.
Field identification & locations
Look for a speckled, interlocking mix of light quartz/feldspar and dark minerals, unlike layered sedimentary rocks. Granite is widespread in continental mountain belts and ancient cratons; a photo cannot establish its exact locality or mineral proportions.
