Rock Identifier
Fossil bivalve shell (Fossilized or calcitic bivalve, likely a scallop-type pectinid (Bivalvia: Pectinidae)) — fossil
fossil

Fossil bivalve shell

Fossilized or calcitic bivalve, likely a scallop-type pectinid (Bivalvia: Pectinidae)

AI-generated identification · may be incorrect

Primarily calcite (CaCO₃), with strong radial ribs, fan-shaped outline, and a pale cream color; hardness about 3 Mohs, pearly to dull luster, and irregular cleavage. The visible dark material may be matrix, mineral staining, or a broken counterpart.

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Physical properties

Primarily calcite (CaCO₃), with strong radial ribs, fan-shaped outline, and a pale cream color; hardness about 3 Mohs, pearly to dull luster, and irregular cleavage. The visible dark material may be matrix, mineral staining, or a broken counterpart.

Formation & geological history

A marine bivalve shell was buried in sediment and preserved through mineral stabilization or replacement, commonly in limestone or marl; its age cannot be determined from the image alone. Such fossils range from Paleozoic to Recent deposits.

Uses & applications

Collected as a natural-history specimen and used in teaching, display, and sometimes decorative fossil crafts; this example is not a gemstone or construction material.

Geological facts

Radial ribs and the fan-like form are characteristic of scallops and related bivalves; the hinge and two-valve symmetry are useful for more precise identification.

Field identification & locations

Look for repeated ribs, a central hinge region, shell curvature, and sedimentary matrix; common sources include marine limestones worldwide, especially Europe, North Africa, and North America. Avoid acid testing because calcite dissolves readily.

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Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

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Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

sedimentary
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Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

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Weathered fossil bone fragment (identification uncertain)

Fossilized bone; exact taxon and mineral composition cannot be determined from the image

fossil