sedimentary

Fossilized Coral

Scleractinian Anthozoa (Fossilized Calcium Carbonate, CaCO3)

AI-generated identification · may be incorrect

Hardness: 3-4 (Mohs scale); Color: White to off-white/beige; Luster: Dull to earthy; Structure: Visible skeletal corallites with septal patterns; Specific Gravity: 2.5–2.7

Hardness: 3-4 (Mohs scale)
Color: White to off-white/beige
Luster: Dull to earthy

Identified March 30, 2026More sedimentary →

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Physical properties

Hardness: 3-4 (Mohs scale); Color: White to off-white/beige; Luster: Dull to earthy; Structure: Visible skeletal corallites with septal patterns; Specific Gravity: 2.5–2.7

Formation & geological history

Formed through the fossilization of ancient marine coral reefs. Over millions of years (often from the Silurian to the Neogene periods), the organic matter is replaced by minerals or the carbonate skeleton is lithified into limestone in shallow marine environments.

Uses & applications

Used primarily in landscaping (rock gardens), construction as an aggregate, aquarium decoration, and as display specimens for collectors. Highly silica-replaced versions (Agatized Coral) are used in jewelry.

Geological facts

Fossilized coral is a 'stone' that was once a living creature. Ancient coral reefs can be found in land-locked locations like Michigan or Florida, indicating where ancient oceans once covered the continents.

Field identification & locations

Identify by looking for radial, star-shaped, or hive-like patterns (corallites) on the surface. Commonly found in limestone quarries, coastal areas, and ancient sea beds. It reacts with acid (effervescence) due to its calcium carbonate content.