sedimentary

Fossiliferous Limestone (with Crinoids/Coral)

Fossiliferous Limestone (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs scale); Color: dark gray to brownish with white/tan fossil inclusions; Luster: dull to earthy; Texture: clastic/biogenic; Cleavage: none (conchoidal fracture).

Hardness: 3-4 (Mohs scale)
Color: dark gray to brownish with white/tan fossil inclusions
Luster: dull to earthy

Identified May 9, 2026More sedimentary →

Explore Fossiliferous Limestone (with Crinoids/Coral) in the encyclopedia →

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Physical properties

Hardness: 3-4 (Mohs scale); Color: dark gray to brownish with white/tan fossil inclusions; Luster: dull to earthy; Texture: clastic/biogenic; Cleavage: none (conchoidal fracture).

Formation & geological history

Formed in warm, shallow marine environments through the accumulation of calcium carbonate and biological remains like coral or crinoids during the Paleozoic era.

Uses & applications

Commonly used in construction, as a source for lime (cement), in landscaping, and as a popular specimen for fossil collectors.

Geological facts

Many of these rocks found in the Great Lakes region are 'pudding stones' or beach-worn fossils that have been tumbled smooth by glacial and wave action over thousands of years.

Field identification & locations

Look for visible white or cream-colored patterns against a darker matrix that look like rings, stars, or tubes. It react with dilute hydrochloric acid. It is commonly found on Great Lakes shorelines.