The open encyclopedia of minerals
GlossaryCite the database
Mineralogist.org
Minerals A–ZSearchCollectionsBrowse by PropertyIdentify a SpecimenCompare MineralsLocalities MapGlossaryContribute Search the Database →
Mineraloid · Carbonate

Coral

Aragonite skeleton

Aragonite skeletons of colonial corals, worked since antiquity.

Hardness3–4
Crystal systemOrthorhombic
ClassCarbonate
←PrevCoquimbiteNextCoralloite→
Coral specimen

Corallium rubrum (Linnaeus, 1758) - polished precious red coral from offshore Morocco. (specimen at left is ~2.3 centimeters across at its widest) Precious red — Photo: James St. John · CC BY 2.0

Coral

Also known as: Precious coral, Red coral.

Fossilized calcium-carbonate skeletons of colonial marine invertebrates — an organic gem material rather than a true mineral.

Intro adapted from Wikipedia (CC BY-SA).

Coral is a mineraloid, with the chemical formula Aragonite skeleton.

It crystallizes in the orthorhombic crystal system.

Key properties: Mohs hardness 3–4; typically red or pink or white or black.

Collections: Gemstones.

Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet. Browse more C minerals or help write this entry.