gemstone
Red Coral
Corallium rubrum
Hardness of 3.5 on the Mohs scale, vibrant red to pinkish-red color, vitreous to dull luster, organic amorphous crystal structure (calcium carbonate skeleton), specific gravity around 2.60 to 2.70.
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Physical properties
Hardness of 3.5 on the Mohs scale, vibrant red to pinkish-red color, vitreous to dull luster, organic amorphous crystal structure (calcium carbonate skeleton), specific gravity around 2.60 to 2.70.
Formation & geological history
Formed by marine colonial invertebrates (octocorals) that secrete skeletons of calcium carbonate in tropical and subtropical ocean waters, growing over decades to centuries.
Uses & applications
Primarily used in high-end fine jewelry, carvings, and ornamental art pieces due to its striking natural red color.
Geological facts
Precious coral has been harvested for thousands of years, highly valued in ancient civilizations including Rome, Egypt, and Native American cultures for protective and decorative purposes.
Field identification & locations
Identified by its organic composition, reactive fizz with weak acid (calcium carbonate), characteristic white streak or faint growth patterns, and vibrant red hue. Found in the Mediterranean Sea, Pacific Ocean, and near Japan.
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