mineral

Nacre (Mother of Pearl)

Nacre (Biogenic Aragonite/Calcite composite, CaCO3)

Hardness: 3.5; Color: Iridescent white, cream, tan, or golden; Luster: Pearly to iridescent; Structure: Orthorhombic/Hexagonal (micro-lamellar); Specific Gravity: 2.7-2.8

Hardness: 3
Color: Iridescent white, cream, tan, or golden
Luster: Pearly to iridescent

Identified January 29, 2026More mineral →

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Physical properties

Hardness: 3.5; Color: Iridescent white, cream, tan, or golden; Luster: Pearly to iridescent; Structure: Orthorhombic/Hexagonal (micro-lamellar); Specific Gravity: 2.7-2.8

Formation & geological history

Formed as an organic-inorganic composite material produced by some mollusks (such as pearl oysters and mussels) as an inner shell layer through biomineralization.

Uses & applications

Extensively used in jewelry (beads, pendants), button manufacturing, musical instrument inlays, and luxury furniture decor.

Geological facts

Nacre is exceptionally strong despite being composed of brittle calcium carbonate; its brick-and-mortar microstructure prevents crack propagation. It is a 'biomineral,' meaning it is made by a living organism.

Field identification & locations

Identified by its characteristic 'orient' or rainbow-like iridescence when rotated. Found globally in marine and freshwater environments where mollusks thrive. Collectors should look for a smooth, cool surface and unique banded or swirling patterns.

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