metamorphic

Tumbled gray quartz-rich stone, possibly quartzite or chert

Likely quartzite (microcrystalline SiO₂), though the photograph cannot distinguish it confidently from gray chert or silicified limestone

AI-generated identification · may be incorrect

Gray, rounded, polished surface with rusty-brown iron-oxide staining and subtle veining; likely vitreous to waxy luster, Mohs hardness about 6.5–7, noncleaving, and specific gravity around 2.6. The opaque appearance suggests fine-grained quartz rather than a transparent crystal.

Identified September 3, 2026More metamorphic →

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At a glance

Common name: Tumbled gray quartz-rich stone, possibly quartzite or chert
Scientific name: Likely quartzite (microcrystalline SiO₂), though the photograph cannot distinguish it confidently from gray chert or silicified limestone
Category: metamorphic
Identified: September 3, 2026
Method: Standard

AI Estimated Value

$2–$15 for a common tumbled stone; distinctive patterns or verified locality specimens may sell for $20–$50.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Quartzite forms when quartz-rich sandstone is metamorphosed under heat and pressure; chert forms by silica precipitation or replacement in sedimentary settings. These materials range from Precambrian to recent geological ages and are commonly rounded by stream or glacial transport.

Uses & applications

Used as aggregate, road stone, decorative rock, and occasionally lapidary material; this specimen is primarily suitable for collecting or display.

Geological facts

Iron oxides produce the orange-brown patches; tumbling smooths edges and enhances luster. A steel file or quartz crystal should not scratch genuine quartz-rich material, while a glass plate should be scratched by it.

Field identification & locations

Commonly found in river gravel, glacial deposits, and quartzite-bearing terrains worldwide, including the Appalachians, Rocky Mountains, and many glacial regions. Exact identification requires a scratch test, streak, and examination of texture or thin section.