sedimentary
Fossilized Crinoid Stem Columnal
Phylum Echinodermata; Class Crinoidea (CaCO3)
Hardness: 3 (calcite); Color: Grey, tan, or white; Luster: Dull to earthy; Crystal Structure: Trigonal/Hexagonal; Shape: Disc-like or cylindrical with a central hole (lumen); Specific Gravity: 2.7.
- Hardness
- 3 (calcite)
- Color
- Grey, tan, or white
- Luster
- Dull to earthy
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Physical properties
Hardness: 3 (calcite); Color: Grey, tan, or white; Luster: Dull to earthy; Crystal Structure: Trigonal/Hexagonal; Shape: Disc-like or cylindrical with a central hole (lumen); Specific Gravity: 2.7.
Formation & geological history
Formed through the fossilization of marine organisms' skeletal fragments in low-energy marine environments. Most common in Paleozoic limestone deposits ranging from 250 to 500 million years old.
Uses & applications
Used primarily for educational purposes, paleontological study, and in lapidary work as 'bead stones' or 'Indian beads'. Large deposits are sometimes quarried for limestone production in construction.
Geological facts
Crinoids are often called 'Sea Lilies' because they resemble plants, though they are actually animals related to starfish. Their stems were composed of hundreds of individual stacked discs called columnals.
Field identification & locations
Identify by looking for perfect circular or star-shaped discs with a hole in the center, often found in limestone outcrops or riverbeds. They are frequently found in the Midwestern United States (Indiana, Kentucky, Ohio).
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