Pearl (incorporated into jewelry)

Physical Properties

Hardness: 2.5–4.5; Color: White/Cream/Iridescent; Luster: Pearly; Crystal structure: Orthorhombic (aragonite); Cleavage: None; Specific Gravity: 2.60–2.85

Formation & Geological History

Biogenic origin; formed within the soft tissue (mantle) of a living shelled mollusk. Consists of nacre deposited in layers around a microscopic irritant.

Uses & Applications

Primary use is in high-end jewelry and ornamentation; also used in traditional medicine and cosmetics in powder form.

Geological Facts

Commonly known as 'organic gemstones' because they are created by living organisms. The luster of pearls depends on the reflection, refraction, and diffraction of light from the translucent layers.

Field Identification & Locations

Identify by the 'tooth test' (feels gritty against teeth) and checking for concentric layering. Commonly found in pearl oysters (saltwater) and mussels (freshwater).

Identified on: 4/26/2026

Mode: Standard