igneous
Red granite or granitic gneiss fragment
Felsic granitoid, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, pink-red and gray, with a granular texture and vitreous to dull luster; typical hardness is about 6–7 Mohs, with no prominent cleavage and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, pink-red and gray, with a granular texture and vitreous to dull luster; typical hardness is about 6–7 Mohs, with no prominent cleavage and specific gravity around 2.6–2.7.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the crust, generally during Precambrian or younger continental plutonic events; the pictured piece may be weathered or slightly metamorphosed.
Uses & applications
Used as crushed aggregate, building stone, monuments, countertops, and landscaping rock; small pieces have modest collecting interest.
Geological facts
The red color commonly comes from iron-bearing potassium feldspar, while dark flecks are usually biotite or amphibole.
Field identification & locations
Identify it by visible interlocking crystals, abundant pink feldspar, gray translucent quartz, and dark mica; common in continental shields, mountain belts, and glacial deposits. A precise identification would require a fresh surface or thin section.
