metamorphic
Polished gray pebble, likely quartzite or chert
Quartzite (mostly SiO₂), tentative identification
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray to bluish-gray, fine-grained, and glassy to waxy luster. The rounded, polished surface obscures grain, cleavage, and original texture; specific gravity is roughly 2.6–2.7.
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Physical properties
Hardness about 7 Mohs; pale gray to bluish-gray, fine-grained, and glassy to waxy luster. The rounded, polished surface obscures grain, cleavage, and original texture; specific gravity is roughly 2.6–2.7.
Formation & geological history
If quartzite, it formed when quartz-rich sandstone was metamorphosed under heat and pressure, commonly during Precambrian–Phanerozoic mountain building. It was later weathered and rounded in a river, beach, or glacial environment, then polished by humans.
Uses & applications
Suitable as a decorative stone, paperweight, cabochon, or craft material; it has little industrial value at this small size. Value is mainly aesthetic rather than gemological.
Geological facts
The image does not show diagnostic crystal faces or banding, so chert, quartz-rich jasper, or another hard silicate pebble is also possible. A steel file should not easily scratch it; glass-scratching supports quartz-rich composition.
Field identification & locations
Common in river gravels and beaches worldwide, especially near quartz-rich metamorphic or sedimentary terrains. Confirm with a fresh surface, streak test, hardness test, and ideally a loupe or specific-gravity measurement.
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