fossil

Polished fossil ammonite

Ammonite cephalopod fossil, likely an ammonite mold/cast in calcite or aragonite-derived mineralization

AI-generated identification · may be incorrect

Typically calcite-replaced shell or sedimentary infill; Mohs hardness about 3–4, earthy to waxy luster, brown-gold coloration, and visible chambered spiral structure. Irregular fracture and possible calcite veins are common.

Identified September 13, 2026More fossil →

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At a glance

Common name: Polished fossil ammonite
Scientific name: Ammonite cephalopod fossil, likely an ammonite mold/cast in calcite or aragonite-derived mineralization
Category: fossil
Identified: September 13, 2026
Method: Standard

AI Estimated Value

Approximately $10–$60 for a common small polished specimen; $75–$300+ for larger, exceptionally preserved, or scientifically documented 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

Ammonites were extinct marine cephalopods that lived from the Devonian to the end-Cretaceous, roughly 400–66 million years ago. Their shells were buried in marine sediment and later mineralized, commonly during Jurassic or Cretaceous deposition.

Uses & applications

Used as decorative polished specimens, fossil-collecting pieces, educational objects, and occasionally jewelry. Value depends strongly on species, size, preservation, polish, and locality.

Geological facts

The spiral chambers represent the animal’s buoyancy-controlled shell compartments; the animal occupied the outermost chamber. This specimen appears cut and polished, exposing internal shell chambers and mineral infill.

Field identification & locations

Identify it by the coiled planispiral form, repeated septa/chambers, and fossilized shell texture; agate-like banding may indicate mineral replacement. Common sources include Morocco, Madagascar, Madagascar, England, Germany, and Canada.