mineral
Pearl (Biogenic Mineraloid)
Calcium carbonate (CaCO3) primarily as Aragonite
Hardness: 2.5-4.5; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); 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; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Specific gravity: 2.60-2.85
Formation & geological history
Biogenic formation within the soft tissue (mantle) of a living shelled mollusk or other animal as a defense mechanism against irritants.
Uses & applications
Predominantly used in jewelry (necklaces, earrings, rings) and as a gemstone for collectors; historically used in cosmetics and traditional medicine.
Geological facts
Pearls are the only gemstones made by living creatures. The most famous pearl is 'La Peregrina', once owned by Elizabeth Taylor.
Field identification & locations
Identify by 'tooth test' (gritty feel against teeth) or looking for surface irregularities under magnification. Found in saltwater (oysters) or freshwater (mussels).
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