Mother of Pearl and Onyx

Physical Properties

Hardness: 3.5-4 (MOP), 6.5-7 (Onyx); Color: Iridescent white/nacreous and black; Luster: Pearly and Vitreous; Structure: Orthorhombic (Aragonite), Trigonal (Quartz/Chalcedony)

Formation & Geological History

Mother of Pearl is organic-geological, formed as a lining in mollusk shells. Onyx is a cryptocrystalline form of quartz formed in gas cavities in volcanic rocks (lava).

Uses & Applications

Primary use is in fine and decorative jewelry, inlay work, buttons, and watch faces.

Geological Facts

Mother of Pearl (nacre) and Onyx have been used together in Zuni and Navajo inlay jewelry for over a century; Onyx was historically believed to provide protection and strength.

Field Identification & Locations

Identify by the signature iridescence/pearly play of color in the white sections and the high-polish, opaque deep black of the onyx. These materials are often used in 'mosaic' or 'channel' inlay techniques.

Identified on: 4/25/2026

Mode: Standard