Rock Identifier
Fossilized Limestone with Crinoid Stem (Carboniferous Limestone (containing Crinoidea ossicles)) — fossil
fossil

Fossilized Limestone with Crinoid Stem

Carboniferous Limestone (containing Crinoidea ossicles)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs); Color: Tan, beige, or light gray; Luster: Dull/Earthy; Structure: Massive sedimentary matrix with circular/cylindrical fossil inclusions; Cleavage: None (conchoidal to irregular fracture).

Hardness
3-4 (Mohs)
Color
Tan, beige, or light gray
Luster
Dull/Earthy
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Physical properties

Hardness: 3-4 (Mohs); Color: Tan, beige, or light gray; Luster: Dull/Earthy; Structure: Massive sedimentary matrix with circular/cylindrical fossil inclusions; Cleavage: None (conchoidal to irregular fracture).

Formation & geological history

Formed in shallow, warm marine environments where calcium carbonate precipitated and remains of sea creatures accumulated on the ocean floor. Most common in Paleozoic era strata (approx. 250-500 million years old).

Uses & applications

Used primarily for geological study, educational collections, and sometimes in decorative landscaping or construction as dimension stone. Smaller specimens are common hobbyist collectibles.

Geological facts

The circular indentation visible on the surface is a cross-section of a crinoid stem columnal. Crinoids are 'sea lilies,' animals related to starfish and sea urchins that have existed for hundreds of millions of years.

Field identification & locations

Identify in the field by looking for 'cheerio' or 'button' shaped imprints in sedimentary rock. They are commonly found in limestone outcrops, creek beds, and gravel pits across the Midwest US and UK.

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Phylum Echinodermata, Class Crinoidea

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