sedimentary

Chert with Crinoid Fossil Impression

Microcrystalline Quartz (SiO2) with Crinoidea fossil impression

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Yellow-brown, tan, ochre; Luster: Waxy to dull; Structure: Cryptocrystalline/Amorphous; Conchoidal fracture; Opaque.

Hardness: 7 (Mohs scale)
Color: Yellow-brown, tan, ochre
Luster: Waxy to dull

Identified June 12, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale); Color: Yellow-brown, tan, ochre; Luster: Waxy to dull; Structure: Cryptocrystalline/Amorphous; Conchoidal fracture; Opaque.

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments during various geological eras (often Paleozoic for such fossils). This specimen shows a cast/impression of a crinoid stem segment.

Uses & applications

Used historically for stone tools due to conchoidal fracture; modern uses include landscaping and as collector specimens for paleontological interest.

Geological facts

Crinoids are also known as 'sea lilies,' though they are animals related to starfish rather than plants. Their segmented stems are one of the most common fossils found in sedimentary rocks.

Field identification & locations

Identify by its waxy luster, high hardness (will scratch glass), and the characteristic ribbed 'screw-thread' impression of a crinoid stem. Commonly found in limestone and shale deposits globally.