Coral
Organic gem made of calcite
Rare · CaCO₃ (calcite) with organic matter
The skeleton of precious coral (Corallium), a branching colony up to about a metre high growing on rocky sea floors in dim, clean water between 10 and 300 metres down. The skeleton is calcium carbonate; carotenoid pigments give it its red. Worn since ancient Egypt and prehistoric Europe.
Identity
- Formula
- CaCO₃ (calcite) with organic matter
- Chemical class
- Carbonate
- Also known as
- Precious coral, Red coral, Corallium rubrum
Crystallography
- Crystal system
- Trigonal
- Habits
- Dendritic
- Fracture
- Splintery
Physical properties
- Mohs hardness
- 3.5
- Density
- 2.65 g/cm³
- Luster
- Dull, Vitreous
- Colors
- red, pink, white, orange
- Streak
- white
- Transparency
- Translucent, Opaque
Geology
- Origins
- Sedimentary
- Host rocks
- Limestone and chalk
- Associated minerals
- Calcite
- Geography
- Mediterranean Sea, Eastern Atlantic coast, Western Pacific
Classification
- Rarity
- Rare
- Gem quality
- Yes
Arcane properties
- Affinity
- Water, Life
- Effects
- Healing, Warding
- Planar origin
- Material Plane
Sources
- Coral. Mindat.org (Hudson Institute of Mineralogy).
- Coral. Gemdat.org (Hudson Institute of Mineralogy).
- James Shigley, Historical Reading List: Mediterranean Precious Coral. Gemological Institute of America.
- Captivated by Coral. Gemological Institute of America, GIA 4Cs, 2014.
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