fossil

Agatized Fossil Coral

Agatized Anthozoa

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs), Color: Brown, tan, grey, Luster: Waxy to vitreous when polished, Crystal structure: Microcrystalline quartz replacing original organic structure, Cleavage: None, Specific gravity: 2.58-2.64

Hardness: 6

Identified August 25, 2026More fossil →

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Physical properties

Formation & geological history

Formed when ancient coral is buried and the original calcium carbonate skeleton is slowly replaced by silica-rich water over millions of years, turning it into chalcedony/agate. Often found in marine deposits from the Oligocene to Miocene epochs.

Uses & applications

Used in jewelry making, cabochons, and collected by rockhounds and fossil enthusiasts.

Geological facts

Agatized coral is the state rock of Florida. The replacement process preserves the intricate details of the original coral structure.

Field identification & locations

Can be identified by the characteristic polyp patterns (star-like or honeycomb shapes) visible on the surface or when cut. Often found in riverbeds, beaches, or eroded limestone deposits in areas like Florida, Georgia, and Indonesia.