igneous
Weathered granite (likely granitic river cobble)
Granite; primarily quartz, feldspar, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, tan to pinkish-gray rock with dark mafic minerals and a granular texture; hardness about 6–7 Mohs, vitreous to dull luster, no prominent cleavage as a whole, and specific gravity roughly 2.6–2.7.
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Physical properties
Coarse-grained, tan to pinkish-gray rock with dark mafic minerals and a granular texture; hardness about 6–7 Mohs, vitreous to dull luster, no prominent cleavage as a whole, and specific gravity roughly 2.6–2.7.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic plutonic events. The rounded shape and surface weathering suggest transport by water or glacial action.
Uses & applications
Used extensively as building stone, countertops, monuments, paving, aggregate, and landscaping material; this small weathered specimen has mainly educational or minor collectible value.
Geological facts
The light minerals are usually quartz and potassium feldspar, while black patches are biotite or amphibole. Pink coloration commonly reflects potassium feldspar and iron oxidation from weathering.
Field identification & locations
Identify it by visible interlocking grains of pale quartz/feldspar and black minerals, unlike volcanic rocks with microscopic crystals. Common worldwide, especially in continental mountain belts and granitic terrains.
