mineral

Pearl

Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3

AI-generated identification · may be incorrect

Hardness: 2.5–4.5 (Mohs scale); Color: White, cream, pink, silver, or black; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (as aragonite); Cleavage: None; Specific Gravity: 2.60–2.85

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

Identified April 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed within the soft tissue of a living shelled mollusk. It is biogenic, created through the secretion of nacre (mother-of-pearl) around an irritant. It is organic in origin rather than strictly inorganic/geological.

Uses & applications

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

Geological facts

Pearls are the only gemstones made by living animals. The world's largest pearl, the Pearl of Lao Tzu, weighs over 6 kilograms. They are the traditional birthstone for June.

Field identification & locations

Identify by the 'tooth test' (feels gritty against teeth) or by observing surface growth patterns under magnification. Found in marine or freshwater environments globally where oysters and mussels thrive.