metamorphic
Weathered quartz-bearing rock, possibly granitic gneiss
Quartz–feldspar–mica aggregate; exact identification requires testing
AI-generated identification · may be incorrectGray, rounded, fine- to medium-grained specimen with visible pale crystals and dark mineral flecks; likely Mohs 6–7, vitreous to dull luster, interlocking grains, and no obvious cleavage in the whole rock.
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Physical properties
Gray, rounded, fine- to medium-grained specimen with visible pale crystals and dark mineral flecks; likely Mohs 6–7, vitreous to dull luster, interlocking grains, and no obvious cleavage in the whole rock.
Formation & geological history
Probably formed from quartz- and feldspar-rich igneous material later metamorphosed or strongly weathered; its geological age cannot be determined from the photograph.
Uses & applications
Primarily a collecting specimen; comparable granite or gneiss is used for dimension stone, countertops, aggregate, and monuments, but this small piece has little commercial use.
Geological facts
The pale grains may be quartz or weathered feldspar, while dark grains may be biotite, amphibole, or iron oxides; the brown-gold patches could be surface staining or sulfide alteration.
Field identification & locations
Common in continental crust and glacial or stream gravels worldwide. A glassy quartz grain scratches glass, while feldspar commonly shows cleavage; a fresh broken surface and magnification would improve identification.
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