sedimentary

Petrified Coral (Agatized Coral)

Anthozoa (Agatized Fossil)

AI-generated identification · may be incorrect

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

Identified June 24, 2026More sedimentary →

Explore Petrified Coral (Agatized Coral) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

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.