sedimentary
Fossiliferous Limestone with Crinoid stems
Limestone (CaCO3) containing Crinoidea fossils
Hardness: 3-4 (Mohs scale), Color: light gray to tan, Luster: dull/earthy, Crystal structure: microcrystalline calcite matrix with visible fossil bioclasts, Cleavage: varies by fossil inclusion.
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Physical properties
Hardness: 3-4 (Mohs scale), Color: light gray to tan, Luster: dull/earthy, Crystal structure: microcrystalline calcite matrix with visible fossil bioclasts, Cleavage: varies by fossil inclusion.
Formation & geological history
Formed in shallow, calm marine environments from the accumulation of calcium carbonate and skeletal remains of marine organisms. The fossilized crinoids suggest Paleozoic to Mesozoic era formation.
Uses & applications
Used in construction as aggregate, in lime production for agriculture, and as decorative stone. Small specimens are popular for educational purposes and fossil collecting.
Geological facts
Crinoids are also known as 'sea lilies' though they are animals related to starfish. Their segmented stems are the most common fossil part found because they break apart easily after the animal dies.
Field identification & locations
Identify in the field by looking for small, disc-shaped or gear-like segments (columnals) often with a central hole. It will fizz when exposed to dilute hydrochloric acid. Commonly found in limestone outcrops and riverbeds.
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