igneous
Granite or granitic gneiss fragment
Felsic granitoid, chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled pink-gray rock with interlocking crystals; quartz and feldspar give a vitreous to dull luster, while dark mica/amphibole creates black grains. Hardness is about 6–7 Mohs; cleavage occurs in feldspars and mica, but the specimen appears massive overall.
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Physical properties
Coarse-grained, speckled pink-gray rock with interlocking crystals; quartz and feldspar give a vitreous to dull luster, while dark mica/amphibole creates black grains. Hardness is about 6–7 Mohs; cleavage occurs in feldspars and mica, but the specimen appears massive overall.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the continental crust, typically during Precambrian to Mesozoic mountain-building; if foliated, it may be metamorphosed granitic gneiss.
Uses & applications
Used as building stone, paving, aggregate, monuments, countertops, and decorative dimension stone; ordinary hand specimens have modest collector value.
Geological facts
The pink coloration commonly comes from potassium feldspar, while the dark minerals are biotite or hornblende. Its visible interlocking crystals indicate slow cooling rather than volcanic eruption.
Field identification & locations
Identify it by its coarse texture, pink/white feldspar, translucent-gray quartz, and scattered black minerals; unlike sandstone, it lacks rounded grains or bedding. Common in continental mountain belts and glacial or river gravels.
