Pearl

Physical Properties

Hardness: 2.5-4.5 on Mohs scale; Color: white, cream, yellow, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific gravity: 2.60-2.85

Formation & Geological History

Organic origin; formed within the soft tissue (mantle) of a living shelled mollusk. It is created as a defense mechanism against an irritant by secreting layers of nacre. While biogenic, they are classified as mineraloids in geology.

Uses & Applications

Primarily used in jewelry (necklaces, earrings, rings) and as decorations. Also used in cosmetics and traditional medicines as pearl powder.

Geological Facts

Pearls are the only gemstones created by living creatures. Unlike other stones, they require no cutting or polishing to reveal their beauty. The 'La Peregrina' is one of the most famous historical pearls, once owned by Mary I of England.

Field Identification & Locations

Identify by the 'tooth test' (feeling a gritty texture against teeth) or by checking for concentric growth layers under a loupe. Commonly found in tropical and temperate oceans (saltwater) or rivers/lakes (freshwater) via commercial pearl farming.

Identified on: 5/1/2026

Mode: Standard