fossil

Fossilized coral or silicified organic limestone

Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination

AI-generated identification · may be incorrect

Tan, cream, brown, and gray with visible irregular cellular/concentric fossil textures; likely Mohs 3 for calcite-rich areas or up to 7 where silicified, with dull to waxy luster and no obvious cleavage. The specimen appears naturally weathered rather than manufactured.

Identified August 22, 2026More fossil →

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At a glance

Common name: Fossilized coral or silicified organic limestone
Scientific name: Likely fossil coral (Scleractinia/Tabulata) replaced or cemented by calcite and silica; exact identification requires close examination
Category: fossil
Identified: August 22, 2026
Method: Standard

AI Estimated Value

About $10–$50 for a common hand specimen; $50–$200+ for large, well-preserved, colorful, or polished examples.

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 Paleozoic–Mesozoic marine fossil preserved by burial, mineral-rich groundwater, and partial replacement by calcite or silica; the geological age cannot be determined from the photograph.

Uses & applications

Primarily a collectible, educational specimen, or lapidary material; polished fossil coral may be used in ornamental objects and jewelry, but porous material is generally unsuitable for structural construction.

Geological facts

Fossil coral commonly preserves coral-wall and pore patterns, while silicification can produce contrasting brown and cream zones. Acid effervescence indicates exposed calcite, whereas strongly silicified areas may not react.

Field identification & locations

Look for repeated coral corallites or cellular patterns, curved growth bands, and mineral-filled cavities; common sources include Florida, Indonesia, Madagascar, Morocco, and parts of the western United States. A hand lens and dilute hydrochloric acid/vinegar test can help distinguish calcite from silica.