sedimentary

Tumbled river pebble, likely limestone or weathered chert

Indeterminate carbonate/siliceous pebble; possible micritic limestone or chert

AI-generated identification · may be incorrect

Rounded and naturally or mechanically smoothed, tan-gray with mottled brown patches and dull-to-waxy luster. Hardness is visually uncertain: limestone is ~3–4 Mohs and may fizz with dilute acid, while chert is ~7; no visible cleavage or crystals.

Identified August 29, 2026More sedimentary →

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At a glance

Common name: Tumbled river pebble, likely limestone or weathered chert
Scientific name: Indeterminate carbonate/siliceous pebble; possible micritic limestone or chert
Category: sedimentary
Identified: August 29, 2026
Method: Standard

AI Estimated Value

Typically $0.25–$5 as a common pebble; potentially $5–$20 if it proves to be an attractive or uncommon lapidary material.

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

Likely formed as a sedimentary rock and later rounded by stream, beach, or tumbler abrasion. Its precise geological age and formation environment cannot be determined from the photograph.

Uses & applications

Commonly used as landscaping gravel, decorative stone, aquarium media, and craft material; this specimen has little commercial value unless testing reveals an unusual material.

Geological facts

The pale color and subtle mottling are consistent with limestone, dolostone, or weathered chert, but lighting and surface wear obscure diagnostic features.

Field identification & locations

Test an inconspicuous spot with vinegar or dilute hydrochloric acid: strong fizz suggests calcite-rich limestone; no fizz plus ability to scratch glass suggests chert. Common worldwide in river gravels and sedimentary terrains.