mineral

Pearl

Calcium Carbonate (CaCO3)

Hardness: 2.5–4.5 on Mohs scale; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (aragonite) or Hexagonal (calcite); Specific gravity: 2.60–2.85

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

Identified June 9, 2026More mineral →

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Physical properties

Hardness: 2.5–4.5 on Mohs scale; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (aragonite) or Hexagonal (calcite); Specific gravity: 2.60–2.85

Formation & geological history

Formed biogenically within the soft tissue (specifically the mantle) of living shelled mollusks such as oysters and mussels as a response to an irritant. Layers of nacre are deposited over time.

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and ornamentation. Historically used in cosmetics and traditional medicines.

Geological facts

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

Field identification & locations

Identified by their unique pearly luster and smooth (or slightly gritty when rubbed against teeth) texture. Found in both saltwater and freshwater environments worldwide.