mineral

Pearl

Nacre (Aragonite and Conchiolin), CaCO3

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

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

Identified June 24, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

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

Formation & geological history

Organic origin; formed within the soft tissue (mantle) of a living shelled mollusk as a defense mechanism against irritants. Composed of concentric layers of nacre.

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a pigment in cosmetics or as a decorative inlay.

Geological facts

Unlike minerals formed deep in the Earth, pearls are organic gemstones. The most famous pearl, 'La Peregrina', was owned by Mary I of England and Elizabeth Taylor.

Field identification & locations

Identify by the 'tooth test' (feels gritty against teeth) and checking for orient/iridescence. Natural found in saltwater/freshwater mollusks worldwide; cultured varieties are mass-produced.