mineral
Pearl
Biogenic Calcium Carbonate (Aragonite and Conchiolin), CaCO3
Hardness: 2.5–4.5; Color: White, cream, pink, silver, or peacock; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60–2.85.
- Hardness
- 2
- Color
- White, cream, pink, silver, or peacock
- Luster
- Pearly (iridescent)
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Physical properties
Hardness: 2.5–4.5; Color: White, cream, pink, silver, or peacock; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60–2.85.
Formation & geological history
Formed biologically within the soft tissue of a living shelled mollusk. Layers of nacre are deposited around an irritant such as a parasite or grain of sand over several years.
Uses & applications
Primarily used in jewelry (necklaces, earrings, rings) and as a traditional gemstone. Historically used in cosmetics and medicine (pearl powder).
Geological facts
Pearls are the only gemstones created by living creatures. The most famous pearl is 'La Peregrina,' once owned by Mary I of England and Elizabeth Taylor.
Field identification & locations
Identify in the field by the 'tooth test' (natural pearls feel gritty against teeth, imitations feel smooth). Common locations include the Persian Gulf, waters off Japan, Australia, and freshwater rivers in China.
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