fossil

Fossilized Coral (Petrified Coral)

Anthozoa fossil

Hardness: 6.5 - 7 on the Mohs scale. Color: Grayish-brown, tan, to dark grey with intricate flower-like patterns. Luster: Dull to earthy (unpolished) or vitreous (polished). Structure: Hexagonal or flower-like corallite patterns embedded in matrix.

Hardness: 6
Luster: Dull to earthy (unpolished) or vitreous (polished)

Identified July 27, 2026More fossil →

Explore Fossilized Coral (Petrified Coral) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed when ancient coral reefs were buried under sediment and gradually replaced by silica-rich minerals (such as agate or chalcedony) over millions of years through permineralization. Typically dates from the Devonian to Silurian periods.

Uses & applications

Used extensively for lapidary arts, wire-wrapping, cabochons for jewelry, and as educational decorative specimens for collectors.

Geological facts

Petrified coral is actually a fossilized skeleton of ancient marine animals rather than a simple rock. The unique starburst or daisy-like patterns are the transverse cross-sections of individual corallites.

Field identification & locations

Identified in the field by its distinct flower-like or honeycomb patterns on weathered surfaces. Frequently found in limestone quarries, gravel beds, and coastal deposits in Florida, Michigan (Petoskey stone), and Indonesia.