sedimentary

Crinoid Fossil in Chert

Crinoid (Class Crinoidea) in Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: light gray to off-white; Luster: dull to waxy; Structure: fragmented stem ossicles within a fine-grained silica matrix.

Hardness: 6
Color: light gray to off-white
Luster: dull to waxy

Identified June 8, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: light gray to off-white; Luster: dull to waxy; Structure: fragmented stem ossicles within a fine-grained silica matrix.

Formation & geological history

Formed in marine environments during the Paleozoic era (approx. 250-500 million years ago) through the accumulation of calcium carbonate skeletons later replaced by silica (chertification).

Uses & applications

Primarily used for geological study, education, and as decorative items or collectibles.

Geological facts

Crinoids are known as 'sea lilies' and are actually animals related to starfish, not plants. Their fossilized stem segments are often called 'Indian beads' or 'St. Cuthbert's beads'.

Field identification & locations

Identify by looking for circular or star-shaped cross-sections and stacked disc structures. Commonly found in areas with limestone or chert deposits, particularly throughout the Midwestern United States and the UK.