fossil

Fossil Coral

Hexagonaria / Rugosa / Scleractinia

Hardness of 3 to 4 on the Mohs scale (due to calcification/silicification), colors range from white, grey, brown to tan, dull to waxy luster, fibrous or cellular structure reflecting coral polyps.

Identified August 3, 2026More fossil →

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Physical properties

Hardness of 3 to 4 on the Mohs scale (due to calcification/silicification), colors range from white, grey, brown to tan, dull to waxy luster, fibrous or cellular structure reflecting coral polyps.

Formation & geological history

Formed in ancient shallow warm marine environments, typically during the Paleozoic or Mesozoic eras, where coral skeletons were preserved and mineralized through replacement by silica or calcite over millions of years.

Uses & applications

Used primarily in lapidary arts, cabochons for jewelry, decorative objects, and by fossil collectors.

Geological facts

Fossil coral often undergoes agatization, where the original coral structure is replaced by microcrystalline quartz, making it exceptionally durable and beautiful when polished.

Field identification & locations

Found in sedimentary limestone formations worldwide, often identified by the distinctive star-like or honeycomb patterns left by coral calices; easily spotted in creek beds and quarries in regions with ancient marine history.