gemstone
Freshwater Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite organic composite
Hardness: 2.5-4.5 Mohs. Color: White, cream, pink, with iridescent overtone. Luster: Pearlescent (nacreous). Crystal structure: Orthorhombic microcrystals bound by conchiolin protein.
- Hardness
- 2
- Color
- White, cream, pink, with iridescent overtone
- Luster
- Pearlescent (nacreous)
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Physical properties
Hardness: 2.5-4.5 Mohs. Color: White, cream, pink, with iridescent overtone. Luster: Pearlescent (nacreous). Crystal structure: Orthorhombic microcrystals bound by conchiolin protein.
Formation & geological history
Biogenic formation inside freshwater mussels (Unionidae family) when an irritant or tissue piece is coated with layers of nacre.
Uses & applications
Fine jewelry, necklaces, bracelets, earrings, and ornamental accessories.
Geological facts
Unlike traditional gemstones formed deep in the Earth's crust, pearls are organic gemstones produced by living mollusks.
Field identification & locations
Identified by unique soft pearlescent luster, smooth or slightly ringed surface texture (baroque or off-round shape in freshwater varieties), and cool feel to the touch.
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