mineral
Pearl
Calcium carbonate (CaCO3) - mainly Aragonite
AI-generated identification · may be incorrectHardness: 2.5-4.5 (Mohs scale); Color: White, cream, pink, lavender, or gold; Luster: Pearly (iridescent nacre); Crystal Structure: Orthorhombic/Amorphous; Specific Gravity: 2.60-2.85
- Hardness
- 2
- Color
- White, cream, pink, lavender, or gold
- Luster
- Pearly (iridescent nacre)
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Physical properties
Hardness: 2.5-4.5 (Mohs scale); Color: White, cream, pink, lavender, or gold; Luster: Pearly (iridescent nacre); Crystal Structure: Orthorhombic/Amorphous; Specific Gravity: 2.60-2.85
Formation & geological history
Formed as a biological defense mechanism within the soft tissue of shelled mollusks (oysters or mussels). Concentric layers of aragonite and conchiolin are deposited around an irritant. Modern pearls are typically cultured (farmed).
Uses & applications
Primarily used in jewelry for necklaces, bracelets, and earrings. Also used in cosmetics and traditional medicine when ground into powder.
Geological facts
Pearls are the only gemstones created by living animals. The largest pearl ever found is the Pearl of Lao Tzu, weighing over 14 pounds. They are the birthstone for June.
Field identification & locations
Identify by the 'tooth test' (rubbing against teeth feels gritty, not smooth), or checking for subtle surface irregularities. Commonly found in coastal salt waters or freshwater rivers and lakes worldwide.
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