gemstone
Freshwater Pearl
Calcium Carbonate (CaCO3) in the form of Aragonite and Calcite
Hardness: 2.5–4.5; Color: Creamy white with iridescent orient; Luster: Pearly; Structure: Orthorhombic (Concentric layers); Specific Gravity: 2.60–2.85.
- Hardness
- 2
- Color
- Creamy white with iridescent orient
- Luster
- Pearly
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Physical properties
Hardness: 2.5–4.5; Color: Creamy white with iridescent orient; Luster: Pearly; Structure: Orthorhombic (Concentric layers); Specific Gravity: 2.60–2.85.
Formation & geological history
Formed biogenically within the soft tissue (mantle) of living mollusks, typically freshwater mussels. It is a defense mechanism against irritants, where nacre is secreted in layers.
Uses & applications
Primarily used in jewelry for necklaces, bracelets (like the one shown), and earrings. Also used in cosmetics and traditional medicine (pearl powder).
Geological facts
Unlike other gemstones mined from the earth, pearls are organic gems. The 'tooth test' is a common way to identify them; natural pearls feel gritty against the teeth, while imitations feel smooth.
Field identification & locations
Identified by their unique luster and irregular 'rice' or 'potato' shapes when cultured in freshwater. Commonly found in rivers and lakes of China, Japan, and the USA.
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