fossil

Polished fossil shell fragment

Likely fossilized bivalve shell; mineralized aragonite/calcite (exact taxon indeterminate)

AI-generated identification · may be incorrect

Cream, gray, and brown banding follows curved shell growth lines; has a pearly to dull luster, layered fibrous texture, and irregular fracture. Hardness is approximately 3–4 Mohs if calcitic, or 3.5–4.5 if aragonitic; specific gravity about 2.6–2.9.

Identified August 30, 2026More fossil →

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Physical properties

Formation & geological history

Originally formed as a mollusk shell in marine sediment, then buried and partially mineral-replaced during diagenesis. Its geological age cannot be determined from the photograph and may range from Paleozoic to Cenozoic.

Uses & applications

Used as a fossil specimen, paperweight, or decorative polished stone; scientifically valuable chiefly for identification and paleoenvironmental study.

Geological facts

The parallel bands are shell growth increments rather than mineral crystals. Polishing reveals crossed shell layers and can make fossil material resemble banded agate or petrified wood.

Field identification & locations

Look for curved concentric growth lines, shell-layer structure, and possible hinge or rib features; acid testing should be avoided or done cautiously because calcite may effervesce. Common in marine sedimentary formations worldwide.