sedimentary
Fossilized Coral (Petrified Coral)
Anthozoa (Scleractinia)
Hardness: 6.5-7 (Mohs scale), Color: light gray to tan, Luster: dull to waxy, Structure: microcrystalline quartz replacing calcium carbonate, Cleavage: none.
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: light gray to tan, Luster: dull to waxy, Structure: microcrystalline quartz replacing calcium carbonate, Cleavage: none.
Formation & geological history
Formed when ancient coral reefs were buried by sediment over millions of years and gradually replaced by agate or silica-rich groundwater. Most common in Miocene through Eocene aged deposits.
Uses & applications
Used primarily in jewelry (cabochons), as decorative garden stones, and as collected geological specimens.
Geological facts
Small flower-like or starburst patterns on the surface are actually the fossilized skeletons of individual coral polyps. This specimen shows a water-worn, tumbled history.
Field identification & locations
Identified by circular or hexagonal pore patterns on a stony surface. Common in Florida, Indonesia, and the Great Lakes region. Unlike living coral, petrified coral is mineralized and harder.
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