sedimentary
Limestone Pebble with Crinoid Fossil
Calcium Carbonate (CaCO3) - Fossiliferous Limestone
Hardness: 3 (Mohs), Color: light gray to tan, Luster: dull/earthy, Structure: fine-grained matrix with fossil inclusion, Cleavage: none (conchoidal fracture)
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Physical properties
Hardness: 3 (Mohs), Color: light gray to tan, Luster: dull/earthy, Structure: fine-grained matrix with fossil inclusion, Cleavage: none (conchoidal fracture)
Formation & geological history
Formed in shallow, calm marine environments by the accumulation of shells, coral, and algal debris over millions of years; common in Paleozoic strata.
Uses & applications
Primarily used in construction (roads, concrete), agriculture (lime), and as a collector's specimen for fossil enthusiasts.
Geological facts
This specimen contains a partial fossil of a crinoid stem. Crinoids are marine animals related to starfish and sea urchins that have existed for over 450 million years.
Field identification & locations
Can be identified by its reaction to dilute hydrochloric acid (fizzing) and the presence of visible organic remains. Commonly found in riverbeds and coastal areas with sedimentary bedrock.
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