fossil

Polished fossiliferous limestone, possibly ammonite-bearing

Calcite-rich limestone (CaCO₃), with fossil shell material

AI-generated identification · may be incorrect

Brown to tan, fine-grained carbonate matrix with reflective fossil fragments and dark weathering patches; calcite has Mohs hardness 3, vitreous to dull luster, rhombohedral cleavage, and specific gravity about 2.7. The slab appears cut or polished, with a pale calcitic vein or shell section along one edge.

Identified September 12, 2026More fossil →

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At a glance

Common name: Polished fossiliferous limestone, possibly ammonite-bearing
Scientific name: Calcite-rich limestone (CaCO₃), with fossil shell material
Category: fossil
Identified: September 12, 2026
Method: Standard

AI Estimated Value

About $10–$50 for a common polished slab; $75–$300 or more if the fossil structures are distinctive, well preserved, and locality-documented.

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

Sedimentary marine limestone formed from accumulated carbonate mud and shell debris, commonly during the Paleozoic–Mesozoic eras; later lithification and diagenesis produced the dense slab. Exact age and locality require petrographic or fossil identification.

Uses & applications

Used as a decorative lapidary slab, fossil specimen, or ornamental stone; not typically suitable for high-wear construction because calcite dissolves in acids and scratches relatively easily. Collector value depends on fossil preservation, provenance, and polish.

Geological facts

The metallic-looking flashes are likely reflective fossil surfaces or crystalline calcite, not metal. A drop of dilute hydrochloric acid or vinegar should cause visible effervescence if exposed calcite is present.

Field identification & locations

Identify by strong reaction to acid, relatively low hardness, and visible shell or fossil textures; common sources include marine limestone deposits in Europe, North Africa, Madagascar, and the Americas. Avoid confusing it with polished jasper or iron-rich chert.