mineral

Precious Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Hardness: 3.5; Color: shades of red, pink, and orange; Luster: matte to vitreous when polished; Crystal Structure: Trigonal/Amorphous; Specific Gravity: 2.6-2.7

Hardness: 3
Color: shades of red, pink, and orange
Luster: matte to vitreous when polished

Identified May 9, 2026More mineral →

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Physical properties

Hardness: 3.5; Color: shades of red, pink, and orange; Luster: matte to vitreous when polished; Crystal Structure: Trigonal/Amorphous; Specific Gravity: 2.6-2.7

Formation & geological history

Biogenic formation by marine polyps in deep-sea environments. These are organic gemstones formed from the skeletal remains of coral colonies over centuries.

Uses & applications

Predominantly used in jewelry (beads, cabochons), carvings, and as a collectible gemstone. Historically used as decorative amulets.

Geological facts

Red coral has been traded for over 5,000 years. Unlike photosynthetic coral, Corallium rubrum grows in darkness, either in deep water or in dark caverns.

Field identification & locations

Identify by its distinct wood-grain like growth patterns (striations) visible under magnification and its reaction to acid (effervescence). Found mostly in the Mediterranean Sea.

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