mineral
Pearl
Calcium Carbonate (Aragonite and Calcite), CaCO3
Hardness: 2.5-4.5 (Mohs); Color: White, cream, pink, silver, or black; Luster: Pearly (iridescent); Crystal structure: Orthorhombic; Cleavage: None; Specific gravity: 2.60-2.85
- Hardness
- 2
- Color
- White, cream, pink, silver, or black
- Luster
- Pearly (iridescent)
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Physical properties
Hardness: 2.5-4.5 (Mohs); Color: White, cream, pink, silver, or black; Luster: Pearly (iridescent); Crystal structure: Orthorhombic; Cleavage: None; Specific gravity: 2.60-2.85
Formation & geological history
Biogenic formation within the soft tissue (mantle) of a living shelled mollusk. It is created as a defense mechanism against irritants by secreting layers of nacre.
Uses & applications
Primarily used in jewelry (necklaces, earrings, rings) and as a traditional gemstone. Also used in cosmetics and traditional medicine (pearl powder).
Geological facts
The 'Pearl of Lao Tzu' is one of the largest pearls ever found, weighing over 6 kilograms. Pearls are the only gemstones created by living creatures.
Field identification & locations
Identify by the 'tooth test' (feels gritty when rubbed against teeth) and its characteristic orient (iridescence). Found in both saltwater and freshwater mollusks globally.
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