sedimentary

Polished fossiliferous limestone (likely orbicular/fossil limestone)

Fossiliferous micritic limestone, composed primarily of calcite (CaCO₃)

AI-generated identification · may be incorrect

Typically Mohs hardness 3; dark gray to black matrix with cream fossil fragments and calcite-filled cavities, polished to a glossy luster. Calcite has trigonal crystal structure and perfect rhombohedral cleavage; reacts vigorously with dilute hydrochloric acid.

Identified September 18, 2026More sedimentary →

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At a glance

Common name: Polished fossiliferous limestone (likely orbicular/fossil limestone)
Scientific name: Fossiliferous micritic limestone, composed primarily of calcite (CaCO₃)
Category: sedimentary
Identified: September 18, 2026
Method: Standard

AI Estimated Value

Approximately $10–$40 for a small polished specimen; exceptional fossil detail, size, or documented locality may raise value to $50–$150.

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

Forms from carbonate mud and accumulated marine fossils that lithify through compaction and cementation, commonly during Paleozoic–Mesozoic marine deposition. The specimen has been cut and polished, exposing fossil cross-sections and cavities.

Uses & applications

Used as an ornamental stone, cabochon material, paperweight, and collectible; limestone is also widely used for cement, aggregate, and building stone.

Geological facts

The circular cream features may be crinoid or shell sections, while darker areas are micritic limestone and possible stylolitic or mineral-filled seams. Exact fossil identification requires magnification and locality information.

Field identification & locations

Identify by visible fossil textures, relatively low hardness, and acid effervescence; common sources include Morocco, Madagascar, Spain, and other former shallow-marine limestone regions. Avoid prolonged acid exposure because it etches polished calcite.