igneous
Weathered granitic rock
Granite, likely quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectCoarse-grained, speckled pale gray/tan rock with visible light minerals and dark mica or mafic grains; quartz and feldspar have glassy to dull luster. Hardness is approximately 6–7 Mohs, with no obvious cleavage as a whole rock and typical specific gravity around 2.6–2.8.
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Physical properties
Coarse-grained, speckled pale gray/tan rock with visible light minerals and dark mica or mafic grains; quartz and feldspar have glassy to dull luster. Hardness is approximately 6–7 Mohs, with no obvious cleavage as a whole rock and typical specific gravity around 2.6–2.8.
Formation & geological history
Granite forms when silica-rich magma cools slowly deep within continental crust, allowing large crystals to grow; individual bodies may range from Precambrian to Cenozoic age. The rounded shape and brown surface reflect weathering and abrasion.
Uses & applications
Commonly used as dimension stone, countertops, monuments, paving, aggregate, and landscaping rock; attractive pieces may be polished for decorative use.
Geological facts
The granular texture is called phaneritic, indicating slow underground cooling. Brown staining commonly comes from oxidation of iron-bearing biotite or other minerals.
Field identification & locations
Look for interlocking grains of translucent quartz, white or pink feldspar, and black mica/hornblende; a steel file generally struggles to scratch fresh grains. Common worldwide, especially in continental mountain belts.
