Pearl

Physical Properties

Hardness: 2.5-4.5 (Mohs scale); Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic/Amorphous; Specific gravity: 2.60-2.85

Formation & Geological History

Biogenic formation within the soft tissue of a living shelled mollusk. Layers of nacre are deposited around an irritant over several months to years.

Uses & Applications

Primarily used in jewelry (necklaces, earrings, rings) and as a birthstone. Historically used in cosmetics and traditional medicine.

Geological Facts

Pearls are the only gemstones formed inside a living organism. Unlike most gemstones that must be cut and polished, pearls are naturally beautiful when harvested.

Field Identification & Locations

Identify by the 'tooth test' (feels gritty against teeth) and the presence of nacreous luster. Found in freshwater lakes/rivers or saltwater oceans (oyster beds).

Identified on: 4/25/2026

Mode: Standard