fossil

Coral Fossil (Fossilized Coral)

Hexagonaria or similar rugose/tabulate coral fossil (Calcium Carbonate, CaCO3)

Hardness of 3-4 on the Mohs scale; white, gray, or tan coloration; dull to earthy luster; microcrystalline or replaced quartz structure; specific gravity around 2.6-2.7.

Identified August 5, 2026More fossil →

Explore Coral Fossil (Fossilized Coral) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness of 3-4 on the Mohs scale; white, gray, or tan coloration; dull to earthy luster; microcrystalline or replaced quartz structure; specific gravity around 2.6-2.7.

Formation & geological history

Formed in ancient shallow marine environments when coral polyps secreted calcium carbonate skeletons that were subsequently buried in sediment and preserved through fossilization, often over millions of years (Paleozoic to Cenozoic eras).

Uses & applications

Used primarily in lapidary work, cabochons for jewelry, decorative display pieces, and as collector specimens.

Geological facts

Many fossil corals are replaced by agate or chalcedony during the fossilization process, making them quite durable and beautiful when polished.

Field identification & locations

Easily identified in the field by their distinctive honeycomb, star-like, or tube-like corallite patterns on the surface; commonly found in limestone-rich regions and ancient seabed deposits.

Other fossil specimens

See all

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

fossil

Sedimentary Outcrop (Sandstone/Shale)

Sedimentary bedrock formation (variable composition)

sedimentary

Chert with Fossil Brachiopod

Microcrystalline Quartz (SiO2) with Calcitic Brachiopod inclusion

sedimentary

Crinoid Stem Fossils (Indian Beads / St. Cuthbert's Beads)

Crinoid columnal ossicles (phylum Echinodermata)

fossil

Fossilized Crinoid Stem in Limestone

Crinoidea (Class) in Calcium Carbonate (CaCO3) matrix

fossil

Fossiliferous Limestone

Limestone with embedded fossil cross-section

sedimentary