igneous
Coarse-grained granite, possibly granodiorite
Granite–granodiorite; chiefly quartz, alkali feldspar, plagioclase, and mica
AI-generated identification · may be incorrectMedium- to coarse-grained, speckled white/gray rock with pinkish feldspar, glassy quartz, and dark mica or amphibole; typically Mohs hardness 6–7, vitreous to dull luster, granular interlocking crystals, and no prominent cleavage as a whole.
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Physical properties
Medium- to coarse-grained, speckled white/gray rock with pinkish feldspar, glassy quartz, and dark mica or amphibole; typically Mohs hardness 6–7, vitreous to dull luster, granular interlocking crystals, and no prominent cleavage as a whole.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma cooled slowly deep within continental crust, allowing large crystals to grow; its exact geological age cannot be determined from the photograph and may range from Precambrian to recent geologic periods.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving aggregate, and crushed stone; attractive specimens have modest collector value.
Geological facts
The visible coarse texture indicates slow underground cooling rather than volcanic eruption. Granodiorite resembles granite but generally contains more plagioclase than alkali feldspar.
Field identification & locations
Identify it by its interlocking crystals: quartz is typically gray and glassy, feldspar white or pink, and mica dark and flaky; a steel knife usually will not scratch fresh quartz. Common in continental batholiths worldwide, including North America, Europe, India, and Australia.
