fossil

Polished fossil-bearing shale or mudstone

Fossiliferous carbonaceous mudstone/shale; visible fossils may be bivalves or ammonites, but species cannot be confirmed from the image

AI-generated identification · may be incorrect

Dark gray to black, fine-grained matrix with pale, raised fossil impressions or shell fragments; typically dull to slightly satin luster, thin bedding, and Mohs hardness about 2–4. The specimen appears rounded and polished, obscuring natural cleavage and texture.

Identified August 30, 2026More fossil →

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At a glance

Common name: Polished fossil-bearing shale or mudstone
Scientific name: Fossiliferous carbonaceous mudstone/shale; visible fossils may be bivalves or ammonites, but species cannot be confirmed from the image
Category: fossil
Identified: August 30, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common polished specimen; $50–$200+ if the fossils are well-preserved, identifiable, 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

Fine mud accumulated in a quiet marine or lake environment, compacted and lithified over millions of years; fossils were preserved during burial and mineralization. Geological age and locality cannot be determined visually.

Uses & applications

Primarily a collecting, educational, and decorative specimen; fossiliferous shale has limited construction value because it is weak and splits readily.

Geological facts

The pale markings may be mineral-filled fossil molds, commonly calcite- or silica-replaced shells. A polished surface can make genuine fossils resemble painted or carved designs.

Field identification & locations

Look for consistent fossil symmetry, sedimentary layering, and mineral-filled cavities; a magnifier and hardness/acid tests help distinguish fossils from manufactured decoration. Common worldwide in marine sedimentary basins.