Organic Mineraloid
Pearl (Cultured or Natural)
Aragonite (CaCO3) with Conchiolin
Hardness: 2.5-4.5 (Mohs scale); Color: Cream, white, or silver; Luster: Pearly (orient); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60-2.85
- Hardness
- 2
- Color
- Cream, white, or silver
- Luster
- Pearly (orient)
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Physical properties
Hardness: 2.5-4.5 (Mohs scale); Color: Cream, white, or silver; Luster: Pearly (orient); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60-2.85
Formation & geological history
Formed within the soft tissue of living shelled mollusks (oysters or mussels) as a defense mechanism against irritants. Modern specimens can range from a few years to decades old.
Uses & applications
Primarily used in jewelry (necklaces, earrings, rings) and as a birthstone (June). Historically used in cosmetics and traditional medicine when ground into powder.
Geological facts
A pearl is the only gemstone created by a living animal. The 'La Peregrina' pearl is one of the most famous, historically owned by Spanish royalty and later Elizabeth Taylor.
Field identification & locations
Identify by the 'tooth test' (rub lightly against front teeth to feel for a gritty texture); check for drill hole consistency and luster depth. Common sources include the Persian Gulf, Japan, and the South Pacific.
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