igneous
Likely porphyritic granite or granitic pegmatite fragment
Quartz–feldspar–mica granitoid; exact identification requires testing
AI-generated identification · may be incorrectCoarse, speckled reddish-brown and gray texture with possible translucent quartz and dark mica/amphibole; hardness about 6–7, vitreous to dull luster, no obvious cleavage as a whole rock, and typical specific gravity around 2.6–2.7.
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Physical properties
Coarse, speckled reddish-brown and gray texture with possible translucent quartz and dark mica/amphibole; hardness about 6–7, vitreous to dull luster, no obvious cleavage as a whole rock, and typical specific gravity around 2.6–2.7.
Formation & geological history
Formed when silica-rich magma cooled slowly underground, allowing visible crystals to grow; commonly Precambrian to Phanerozoic in age, depending on its source body.
Uses & applications
Used as crushed aggregate, building stone, countertops, monuments, and landscaping rock; small unattractive fragments generally have negligible commercial value.
Geological facts
The pink/red color commonly comes from potassium feldspar, while gray glassy grains are quartz and dark flakes may be biotite or hornblende.
Field identification & locations
Identify it by its interlocking visible grains and inability to scratch quartz or glass easily; a streak test is usually white, and dilute acid should not fizz. Common worldwide, especially in continental mountain belts and exposed shields.
