mineral
Pearl
Organic Mineraloid (CaCO3 + Conchiolin)
Hardness: 2.5-4.5 (Mohs); Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (Aragonite plates); Specific Gravity: 2.60-2.85
- Hardness
- 2
- Color
- White, cream, pink, silver
- Luster
- Pearly (iridescent)
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Physical properties
Hardness: 2.5-4.5 (Mohs); Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (Aragonite plates); Specific Gravity: 2.60-2.85
Formation & geological history
Formed biogenically within the soft tissue (mantle) of a living shelled mollusk. Layers of nacre are deposited around a microscopic irritant over several years.
Uses & applications
Predominantly used in jewelry (necklaces, rings, earrings), decorative arts, and sometimes in traditional cosmetics/medicine (pearl powder).
Geological facts
They are the only gemstones in the world found inside living creatures. The most famous pearl is 'La Peregrina,' once owned by Elizabeth Taylor.
Field identification & locations
Identify by the 'tooth test' (feels gritty against teeth) or looking for surface growth concentricities. Found in both saltwater and freshwater environments worldwide.
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mineral