Rock Identifier
Fossilized Brachiopod or Gastropod in Chert/Limestone (Phylum Brachiopoda / Mollusca) — fossil
fossil

Fossilized Brachiopod or Gastropod in Chert/Limestone

Phylum Brachiopoda / Mollusca

AI-generated identification · may be incorrect

Hardness: 7 (if chert/quartz matrix) or 3 (if limestone); Color: Tan, brownish-green, grey; Luster: Vitreous to dull; Crystal structure: Microcrystalline or amorphous matrix with calcitic fossil remains; Cleavage: None conchoidal fracture.

Hardness
7 (if chert/quartz matrix) or 3 (if limestone)
Color
Tan, brownish-green, grey
Luster
Vitreous to dull
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Physical properties

Hardness: 7 (if chert/quartz matrix) or 3 (if limestone); Color: Tan, brownish-green, grey; Luster: Vitreous to dull; Crystal structure: Microcrystalline or amorphous matrix with calcitic fossil remains; Cleavage: None conchoidal fracture.

Formation & geological history

Formed in ancient marine environments during the Paleozoic or Mesozoic eras through the accumulation of carbonate shells and subsequent fossilization and mineralization (silicification or calcification).

Uses & applications

Educational value, amateur fossil collecting, geological study, and decorative display.

Geological facts

Brachiopods are marine animals that resemble clams superficially, though they belong to a completely different phylum and date back over 500 million years to the Cambrian period.

Field identification & locations

Found commonly in sedimentary rock formations, riverbeds, and glacial tills worldwide. Look for symmetrical shell impressions or spiral structures embedded in weathering rock.

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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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Weathered fossil bone fragment (identification uncertain)

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

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