sedimentary

Fossiliferous Limestone (Crinoidal)

Bioclastic Limestone (predominantly CaCO3)

Hardness: 3-4 (Mohs scale), Color: Dirty white to dark gray with brown weathering, Luster: Dull/Earthy, Crystal Structure: Microcrystalline matrix with visible calcite fossil inclusions, Cleavage: None (conchoidal to irregular fracture)

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in shallow, high-energy marine environments where skeletal debris (likely crinoid stems or shell fragments) accumulated on the sea floor and were lithified over millions of years, commonly from the Paleozoic era.

Uses & applications

Used primarily in the aggregate industry for road base, cement production, or as decorative garden stones. Larger, polished slabs are used for architectural cladding.

Geological facts

This specimen contains 'hash' fossils, which are fragmented remains of ancient marine organisms. These rocks often serve as a biological 'time capsule' for ancient reef systems that existed hundreds of millions of years ago.

Field identification & locations

Identify in the field by checking for the presence of visible shell or stem fragments and performing an acid test (it will fizz when in contact with diluted HCl or vinegar). Found globally in areas with exposed sedimentary bedrock.

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