mineral

Pearl

Biogenic Calcium Carbonate (Aragonite and Conchiolin), CaCO3

Hardness: 2.5–4.5; Color: White, cream, pink, silver, or peacock; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60–2.85.

Hardness: 2
Color: White, cream, pink, silver, or peacock
Luster: Pearly (iridescent)

Identified March 13, 2026More mineral →

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Physical properties

Hardness: 2.5–4.5; Color: White, cream, pink, silver, or peacock; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60–2.85.

Formation & geological history

Formed biologically within the soft tissue of a living shelled mollusk. Layers of nacre are deposited around an irritant such as a parasite or grain of sand over several years.

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a traditional gemstone. Historically used in cosmetics and medicine (pearl powder).

Geological facts

Pearls are the only gemstones created by living creatures. The most famous pearl is 'La Peregrina,' once owned by Mary I of England and Elizabeth Taylor.

Field identification & locations

Identify in the field by the 'tooth test' (natural pearls feel gritty against teeth, imitations feel smooth). Common locations include the Persian Gulf, waters off Japan, Australia, and freshwater rivers in China.

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