mineral

Pearl

Organic Mineral (CaCO3 with conchiolin)

Hardness: 2.5-4.5 on Mohs scale; Color: White, cream, silver, or pink; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (Aragonite); Cleavage: None; Specific Gravity: 2.60-2.85.

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

Identified May 13, 2026More mineral →

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Physical properties

Hardness: 2.5-4.5 on Mohs scale; Color: White, cream, silver, or pink; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (Aragonite); Cleavage: None; Specific Gravity: 2.60-2.85.

Formation & geological history

Biogenic formation within the soft tissue (mantle) of a living shelled mollusk. Layers of nacre are deposited around a microscopic irritant over several years.

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a decorative embellishment in luxury goods. Historically used in crushed form for cosmetics and traditional medicine.

Geological facts

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

Field identification & locations

Identify by the 'tooth test' (feeling a gritty texture when rubbed against teeth) and its distinctive orient (iridescence). Found globally in both freshwater and saltwater environments where oysters and mussels thrive.