sedimentary

Likely coral fragment or porous limestone

Calcareous biogenic carbonate, primarily calcite (CaCO₃); exact identification is uncertain from the image

AI-generated identification · may be incorrect

Small pale cream, highly porous, irregular cylindrical fragment with dull to slightly sugary luster; likely Mohs hardness 3, with no visible cleavage. Calcite-rich material should effervesce strongly in dilute hydrochloric acid or vinegar, though vinegar may react weakly.

Identified September 5, 2026More sedimentary →

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At a glance

Common name: Likely coral fragment or porous limestone
Scientific name: Calcareous biogenic carbonate, primarily calcite (CaCO₃); exact identification is uncertain from the image
Category: sedimentary
Identified: September 5, 2026
Method: Standard

AI Estimated Value

$1-$10 as an unverified small fragment; $10-$50 if confirmed as an attractive or scientifically identifiable fossil coral specimen.

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 a fragment of fossil coral or shell-derived limestone formed in a shallow marine environment; age cannot be determined visually and may range from modern to hundreds of millions of years. Its pores may represent coral chambers or weathered carbonate texture.

Uses & applications

Commonly collected as a fossil/geological specimen and sometimes used decoratively; carbonate rock is widely used for cement, lime, aggregate, and building stone.

Geological facts

The regular cellular porosity favors coral over ordinary limestone, but the image lacks enough detail for species-level identification. A close-up of the ends and acid reaction would improve confidence.

Field identification & locations

Look for repeating polygonal coral corallites, a consistent fossil lattice, and strong acid fizz; limestone is generally softer than glass and can be scratched by a steel knife. Common in reef limestones and coastal deposits worldwide.