sedimentary

Fossiliferous limestone (coral-rich limestone)

Bioclastic carbonate rock, composed mainly of calcite (CaCO₃), with fossilized colonial coral or bryozoan material

AI-generated identification · may be incorrect

Typically Mohs hardness 3–4, pale gray to cream, dull to slightly vitreous luster, and irregular fracture; calcite may show rhombohedral cleavage and effervesces strongly with dilute hydrochloric acid. The porous, repeated branching or honeycomb texture is characteristic of fossil framework material.

Identified August 21, 2026More sedimentary →

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At a glance

Common name: Fossiliferous limestone (coral-rich limestone)
Scientific name: Bioclastic carbonate rock, composed mainly of calcite (CaCO₃), with fossilized colonial coral or bryozoan material
Category: sedimentary
Identified: August 21, 2026
Method: Standard

AI Estimated Value

About $10–$50 for a common specimen; $75–$200+ for large, polished, or exceptionally well-preserved 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

Formed when carbonate-secreting marine organisms accumulated on a shallow seafloor, were buried, compacted, and cemented; commonly Paleozoic to Cenozoic in age, depending on locality. Some specimens may be reef limestone or fossil coral preserved by calcite replacement.

Uses & applications

Used as a decorative and educational specimen, aggregate, and occasionally building or landscaping stone; attractive polished pieces may be sold as fossil coral. It is generally unsuitable for acidic environments because calcite dissolves readily.

Geological facts

The visible patterns are fossil structures rather than crystal growth. Acid testing, a hand lens, and comparison with known coral or bryozoan textures help distinguish it from ordinary limestone.

Field identification & locations

Common in former shallow-marine regions worldwide, including Florida, the Caribbean, the Mediterranean, and many Paleozoic sedimentary basins. Collector value is usually modest unless fossils are exceptionally clear, large, or from a documented locality.