metamorphic
Weathered quartz-rich river cobble, possibly quartzite
Quartzite (mostly microcrystalline SiO₂), tentatively identified
AI-generated identification · may be incorrectGray-brown, rounded and weathered, with a dull to subtly glassy luster and granular texture. Quartzite is typically Mohs 7, has no cleavage, conchoidal to irregular fracture, and specific gravity about 2.6; the image is insufficient to confirm hardness or composition.
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Physical properties
Gray-brown, rounded and weathered, with a dull to subtly glassy luster and granular texture. Quartzite is typically Mohs 7, has no cleavage, conchoidal to irregular fracture, and specific gravity about 2.6; the image is insufficient to confirm hardness or composition.
Formation & geological history
Likely a durable stream- or river-worn cobble derived from metamorphosed sandstone, though weathered quartz-rich chert is an alternative. Quartzite forms during burial and tectonic metamorphism over millions to hundreds of millions of years; its exact age cannot be determined visually.
Uses & applications
Useful as aggregate, road stone, landscaping material, and occasionally ornamental stone. This ordinary rounded specimen has little commercial or jewelry value.
Geological facts
Its rounded shape indicates transport and abrasion, while the resistant quartz-rich material survives weathering better than surrounding rock. The apparent bluish-gray areas may be surface staining, moisture, or other minerals rather than a distinct gemstone.
Field identification & locations
At approximately 17.2°N, 89.1°W, river gravel from the Maya Mountains and surrounding sedimentary terrain commonly includes resistant quartz-rich cobbles, making this plausible. A glass-scratch test can help: genuine quartzite should scratch ordinary glass, but a fresh broken surface and acid/magnet tests would improve identification.
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