Pearl

Physical Properties

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

Formation & Geological History

Biogenic formation created within the soft tissue of a living shelled mollusk. Layers of nacre are deposited around an irritant. While they can be fossilized, most are modern (Holocene).

Uses & Applications

Primarily used in high-end jewelry (necklaces, earrings, rings). Historical use in cosmetics and traditional medicine.

Geological Facts

Pearls are the only gemstones produced by living animals. The world's most expensive pearl, the Pearl of Lao Tzu, was valued at over $93 million.

Field Identification & Locations

Identified by their unique nacreous luster and 'gritty' feel when rubbed against the edge of a tooth. Commonly found in saltwater oysters or freshwater mussels in Japan, China, and Australia.

Identified on: 5/1/2026

Mode: Standard