Pearl

Physical Properties

Hardness: 2.5–4.5; Color: White, cream, pink, silver; Luster: Pearly; Crystal structure: Orthorhombic (microcrystalline aragonite plates); Cleavage: None; Specific Gravity: 2.60–2.85

Formation & Geological History

Formed within the soft tissue (mantle) of a living shelled mollusk as a defense mechanism against a parasite or irritant. The animal deposits layers of calcium carbonate held together by an organic compound called conchiolin.

Uses & Applications

Primarily used in jewelry (necklaces, earrings, rings) and as decorations. Also used in some skin care products as 'pearl powder'.

Geological Facts

Pearls are the only gemstones in the world yielded by a living animal. Cultured pearls are made by humans introducing an irritant into the mollusk, while natural pearls occur without human intervention.

Field Identification & Locations

Identified by their characteristic 'orient' (iridescence) and smooth yet slightly gritty texture when rubbed against teeth. Found in freshwater lakes/rivers or saltwater oceans where oysters and mussels thrive.

Identified on: 5/1/2026

Mode: Standard