Pearl

Physical Properties

Hardness: 2.5–4.5; Color: White, cream, pink, silver; Luster: Pearly (iridescent); Crystal Structure: Orthorhombic (Aragonite); Specific Gravity: 2.60–2.85

Formation & Geological History

Biogenic formation inside the soft tissue of a living shelled mollusk. Formed as a defense mechanism against irritants by depositing layers of nacre. Age varies based on harvest.

Uses & Applications

Primarily used in jewelry (necklaces, earrings, rings) and ornamentation. Historically used in cosmetics and medicines.

Geological Facts

Unlike minerals formed in the Earth's crust, pearls are organic gemstones produced by living organisms. The 'La Peregrina' is one of the most famous historic pearls.

Field Identification & Locations

Identified by its unique 'orient' (iridescence) and smooth but slightly gritty texture when rubbed against teeth. Found in salt and freshwater environments in oysters and mussels.

Identified on: 5/1/2026

Mode: Standard