sedimentary

Fossil Coral

Scleractinia (Anthos), primarily Calcium Carbonate (CaCO3)

AI-generated identification · may be incorrect

Hardness: 3.5 to 4.0; Color: White, cream, or pale beige; Luster: Dull to earthy; Texture: Porous with visible radial septal structures (corallites); Cleavage: None

Hardness: 3
Color: White, cream, or pale beige
Luster: Dull to earthy

Identified March 22, 2026More sedimentary →

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Physical properties

Hardness: 3.5 to 4.0; Color: White, cream, or pale beige; Luster: Dull to earthy; Texture: Porous with visible radial septal structures (corallites); Cleavage: None

Formation & geological history

Formed by the accumulation of calcium carbonate skeletons from marine polyps. Over millions of years, these remains are buried under sediment and lithified into rock. Most specimens range from the Devonian period to recent Holocene formations.

Uses & applications

Used primarily in home decor, jewelry (when agatized), construction materials (limestone), and as a teaching tool for paleontology.

Geological facts

Fossil corals are direct evidence of ancient warm, shallow seas. While many are found as limestone, 'Agatized Coral' occurs when the original calcium carbonate is replaced by silica, turning it into a semi-precious gemstone over 20-30 million years.

Field identification & locations

Identify in the field by looking for distinct radial, star-like, or honeycomb patterns on the surface of white/grey rocks. Common in limestone quarries or coastal areas like Florida, Indonesia, and Morocco.