sedimentary
Petrified Coral (Agatized Coral)
Anthozoa (Agatized Fossil)
Hardness: 6.5-7 (Mohs scale), Color: tan, yellow, orange and brown, Luster: waxy to vitreous, Crystal structure: cryptocrystalline (silica), cleavage: none, Fracture: conchoidal.
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: tan, yellow, orange and brown, Luster: waxy to vitreous, Crystal structure: cryptocrystalline (silica), cleavage: none, Fracture: conchoidal.
Formation & geological history
Formed when prehistoric coral is buried in sediment and replaced by silica-rich groundwater. Typically dates to the Oligocene or Miocene epochs (20-30 million years ago) or as old as the Silurian.
Uses & applications
Used in lapidary work for cabochons, jewelry, interior decoration, and as a sought-after geological collector specimen.
Geological facts
Agatized coral is officially the state rock of Florida. The fossilization process preserves the delicate skeletal structure of the coral polyp, often creating beautiful flower-like patterns.
Field identification & locations
Identify by the distinct hexagonal or star-shaped polyps visible on the surface. Commonly found in riverbeds, especially in Florida and Georgia (Withlacoochee River) and Indonesia.
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