sedimentary

Fossiliferous Limestone (Crinoidal)

Calcite-bearing bioclastic packstone (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3 (Mohs). Color: Grey to tan with white circular fossil inclusions. Luster: Dull/Earthy. Structure: Massive/Fine-grained with visible fossil fragments. Cleavage: Perfect rhombohedral in calcite crystals, though often hidden in matrix.

Hardness: 3 (Mohs)
Color: Grey to tan with white circular fossil inclusions
Luster: Dull/Earthy

Identified May 21, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed in warm, shallow marine environments through the accumulation of organic debris (specifically crinoid stem fragments and shells) on the sea floor during the Paleozoic era (approx. 300-450 million years ago).

Uses & applications

Primarily used in construction (aggregate, cement), as architectural stone, and for educational/collecting purposes due to fossil content.

Geological facts

The circular white rings are cross-sections of crinoids, also known as 'sea lilies,' which were echinoderms related to modern starfish. When they died, their stacked skeletal columns broke apart into 'cheerio-shaped' discs.

Field identification & locations

Identify in the field by checking for the presence of fossil cross-sections and performing an acid test (it will fizz with weak hydrochloric acid/vinegar). Commonly found in limestone outcrops and riverbeds globally.