sedimentary
Fossiliferous Limestone with Crinoid Stem fragment
Calcite (CaCO3) containing Crinoidea fossils
Hardness: 3 (Mohs); Color: Gray to light tan; Luster: Dull/Earthy; Crystal structure: Trigonal/Hexagonal (calcite matrix); Cleavage: Perfect rhombohedral in calcite matrix; Specific gravity: 2.71
- Hardness
- 3 (Mohs)
- Color
- Gray to light tan
- Luster
- Dull/Earthy
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Physical properties
Hardness: 3 (Mohs); Color: Gray to light tan; Luster: Dull/Earthy; Crystal structure: Trigonal/Hexagonal (calcite matrix); Cleavage: Perfect rhombohedral in calcite matrix; Specific gravity: 2.71
Formation & geological history
Formed in warm, shallow marine environments from the accumulation of calcium carbonate and the skeletal remains of marine organisms. This specimen likely dates from the Paleozoic era (approx. 250-500 million years ago).
Uses & applications
Primarily used for educational collecting, decorative stone, and as a raw material for cement or lime production in industrial contexts.
Geological facts
Crinoids are also known as 'Sea Lilies' and are ancestors to modern starfish and sea urchins. The screw-like impression is a mold of a segmented stem.
Field identification & locations
Identify by looking for stacked, disc-like segments (chevrons) or circular impressions in a fine-grained gray rock. It will react and fizz when exposed to weak acid (vinegar). Found globally in ancient limestone beds.
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