igneous
Red-brown granite or granitic gneiss fragments
Felsic granitoid, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse, granular texture with pink-red feldspar and dark mafic grains; typically Mohs 6–7, vitreous to dull luster, no prominent cleavage as a rock, and specific gravity about 2.6–2.8. The pieces appear weathered or possibly lightly polished, making exact identification uncertain from the image.
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Physical properties
Coarse, granular texture with pink-red feldspar and dark mafic grains; typically Mohs 6–7, vitreous to dull luster, no prominent cleavage as a rock, and specific gravity about 2.6–2.8. The pieces appear weathered or possibly lightly polished, making exact identification uncertain from the image.
Formation & geological history
Crystallized slowly from silica-rich magma deep in the crust, generally during Precambrian to Phanerozoic continental mountain-building; weathering or breaking produced these fragments.
Uses & applications
Used as crushed aggregate, road stone, building stone, countertops, monuments, and landscaping material; attractive pieces may be sold as inexpensive specimens.
Geological facts
Pink coloration commonly comes from potassium feldspar, while dark specks are biotite or amphibole. If foliation or banding is present, the material may instead be granitic gneiss, a metamorphic equivalent.
Field identification & locations
Identify by visible interlocking crystals, pink feldspar, gray-clear quartz, and black mica/amphibole; common worldwide in continental shields and mountain belts. A streak, hardness test, and close inspection for foliation would improve identification.
