sedimentary
Fossilized Coral (Coquina/Limestone)
Cnidaria Anthozoa (Fossilized)
Hardness 3-4 (Mohs scale), off-white to beige color, dull/earthy luster, porous and honeycomb-like skeletal structure made primarily of calcium carbonate (calcite).
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Physical properties
Hardness 3-4 (Mohs scale), off-white to beige color, dull/earthy luster, porous and honeycomb-like skeletal structure made primarily of calcium carbonate (calcite).
Formation & geological history
Formed through the accumulation of coral skeletal remains in shallow tropical marine environments. Over geological time, pressure and chemical precipitation lithify these remains into sedimentary rock.
Uses & applications
Primarily used as a decorative garden stone, building material in coastal regions (as coquina), or as a source of lime for cement. It is also common in educational fossil collections.
Geological facts
Fossil corals can date back hundreds of millions of years, though many found on beaches today are from the more recent Pleistocene epoch. They represent ancient reef systems that are now terrestrial land due to sea level changes.
Field identification & locations
Identify in the field by looking for distinct pit-like or hexagonal geometric patterns (corallites) that resemble a sponge or honeycomb. It will fizz when exposed to dilute hydrochloric acid due to its calcite content.
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