sedimentary

Likely weathered limestone or calcareous tuff

Calcite-rich carbonate rock, chiefly CaCO₃; exact identification is uncertain from the image

AI-generated identification · may be incorrect

Pale yellow, porous, earthy and dull rather than glassy; apparent hardness about Mohs 3, low-to-moderate density, and no visible crystal cleavage. Likely reacts with dilute hydrochloric acid or vinegar if carbonate-rich.

Identified August 14, 2026More sedimentary →

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At a glance

Common name: Likely weathered limestone or calcareous tuff
Scientific name: Calcite-rich carbonate rock, chiefly CaCO₃; exact identification is uncertain from the image
Category: sedimentary
Identified: August 14, 2026
Method: Standard

AI Estimated Value

Typically $0-$5 as an ordinary fragment; approximately $5-$20 if fossiliferous, unusually textured, or from a documented locality.

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

Probably formed by accumulation and cementation of carbonate mud, shell fragments, or porous volcanic-carbonate material; age and precise origin cannot be determined visually. Weathering has produced the rough, cavernous surface.

Uses & applications

Common limestone is used for aggregate, cement, lime, building stone, and soil amendment; an unattractive fragment has little jewelry use. This small specimen may have modest educational or collecting interest.

Geological facts

The strong porosity and yellow-brown weathering resemble limestone, calcareous tuff, or possibly a concretion. A fizz test with dilute acid, streak, and a fresh broken surface would distinguish carbonate rock from many look-alikes.

Field identification & locations

Common worldwide, especially in marine sedimentary basins and karst regions. Test for fizz, scratch with a steel nail, inspect for fossils, and avoid confusing it with lightweight concrete or fired ceramic.