igneous
Weathered quartz-rich pebble, possibly granite or granodiorite
Felsic intrusive rock; chiefly quartz, feldspar, and minor mica/amphibole
AI-generated identification · may be incorrectGray-green, rounded and strongly weathered, with a dull to weakly granular luster and no obvious cleavage. Estimated hardness 6–7 Mohs; crystal grains are fine to medium, and the dark cavity may be a weathered mafic mineral or vesicle-like pit.
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Physical properties
Gray-green, rounded and strongly weathered, with a dull to weakly granular luster and no obvious cleavage. Estimated hardness 6–7 Mohs; crystal grains are fine to medium, and the dark cavity may be a weathered mafic mineral or vesicle-like pit.
Formation & geological history
Likely eroded from an ancient plutonic body and rounded in stream or shoreline transport; intrusive crystallization commonly occurred millions to billions of years ago. Exact age and identity require a fresh surface or laboratory testing.
Uses & applications
Useful mainly as a teaching, landscaping, or curiosity specimen; low commercial value and unsuitable for precise gemstone use.
Geological facts
The greenish coloration may reflect chlorite or epidote produced during alteration of mica or amphibole. Surface weathering can obscure the original granite texture.
Field identification & locations
Common in streambeds, beaches, and areas underlain by granite, gneiss, or related rocks. A streak test, acid test, hand lens, and examination of a broken face would help distinguish granite from metamorphic or sedimentary alternatives.
