mineral

Pearl

Aragonite and Calcite (CaCO3) with Conchiolin

Hardness: 2.5-4.5 on Mohs scale; Color: Cream, white, pink, or silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic/Hexagonal (microcrystalline); Specific Gravity: 2.60-2.85

Hardness: 2
Color: Cream, white, pink, or silver
Luster: Pearly (iridescent)

Identified May 1, 2026More mineral →

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Physical properties

Hardness: 2.5-4.5 on Mohs scale; Color: Cream, white, pink, or silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic/Hexagonal (microcrystalline); Specific Gravity: 2.60-2.85

Formation & geological history

Biogenic formation within the soft tissue of a living shelled mollusk. Formed as a defense mechanism against irritants through the secretion of nacre layers. Geological age depends on the biological lifecycle of the host.

Uses & applications

Primarily used in high-end and fashion jewelry. Cultured pearls are also valued as a symbol of elegance and used in traditional medicines in some cultures.

Geological facts

Pearls are the only gemstones created by living animals. The largest pearl ever found, the Pearl of Lao Tzu, weighs about 14 pounds. Unlike other gemstones, they require no cutting or polishing to reveal their beauty.

Field identification & locations

Identify by the 'tooth test' (feels gritty when rubbed against teeth) or by looking for concentric growth layers under magnification. Found in marine or freshwater environments worldwide where oysters and mussels thrive.