sedimentary

Polished gray pebble

Likely quartz-rich chert or fine-grained quartzite; exact identification is uncertain from the photograph

AI-generated identification · may be incorrect

Hardness likely 6.5–7 Mohs, pale gray-beige color, smooth polished surface, and dull to weakly vitreous luster. It appears massive and fine-grained, with no visible cleavage; specific gravity is likely about 2.6–2.7.

Identified August 22, 2026More sedimentary →

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At a glance

Common name: Polished gray pebble
Scientific name: Likely quartz-rich chert or fine-grained quartzite; exact identification is uncertain from the photograph
Category: sedimentary
Identified: August 22, 2026
Method: Standard

AI Estimated Value

Typically $2–$15 as a polished common specimen; approximately $20–$50 if unusually attractive, large, or confidently identified as quality quartzite or chert.

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

If chert, it formed from silica-rich marine sediment that later lithified; if quartzite, it formed by metamorphism of quartz sandstone. These materials may range from Precambrian to much younger, depending on source locality.

Uses & applications

Commonly used as a tumbled decorative stone, cabochon, paperweight, or craft material; quartzite also serves as aggregate and building stone. It has modest gemstone value unless unusually patterned or collectible.

Geological facts

The uniformly rounded shape and glossy surface indicate human tumbling or polishing rather than natural weathering alone. A steel file should not easily scratch it, while quartz will scratch glass.

Field identification & locations

Commonly found as river gravel, beach cobbles, and silica-rich geological deposits worldwide. Inspect translucency, grain size, and conchoidal fracture; acid testing is generally uninformative.