sedimentary
Crinoid Stem Columns (Fossil)
Crinoidea (Class); often composed of the mineral Calcite (CaCO3)
Hardness: 3 (calcite); Color: Gray to tan; Luster: Dull to vitreous; Structure: Centrally perforated disks or cylinders with radial symmetry (star or gear-like patterns on faces); Cleavage: Rhombohedral (on individual calcite crystals).
- Hardness
- 3 (calcite)
- Color
- Gray to tan
- Luster
- Dull to vitreous
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Physical properties
Hardness: 3 (calcite); Color: Gray to tan; Luster: Dull to vitreous; Structure: Centrally perforated disks or cylinders with radial symmetry (star or gear-like patterns on faces); Cleavage: Rhombohedral (on individual calcite crystals).
Formation & geological history
Formed from the skeletal remains of marine echinoderms known as Sea Lilies. These specimens are fossilized sections of the animal's stalk, usually dating from the Paleozoic era (approx. 250-500 million years ago) in shallow marine environments.
Uses & applications
Used in educational paleontology collections, historical jewelry (as 'bead stones'), and as architectural accents in limestone. They are highly valued by amateur rockhounds and fossil collectors.
Geological facts
In folklore, these fossils were often called 'St. Cuthbert's beads' or 'star stones' and were used as primitive rosary beads. Although they look like plants, crinoids are actually animals related to starfish and sea urchins.
Field identification & locations
Identify in the field by looking for small, button-like or stacked cylindrical shapes in limestone outcrops or river gravel. They are commonly found in the Midwest US and UK. Collectors should look for the characteristic 'hole' in the center of the disk.
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