gemstone

Mother of Pearl (Nacre)

Calcium Carbonate (Aragonite) with organic conchiolin

Hardness: 2.5-4.5 on Mohs scale. Color: Iridescent white, cream, pink, or silvery with pearlescent flash. Luster: Pearly to iridescent. Crystal structure: Orthorhombic (aragonite platelets). Specific gravity: ~2.7.

Hardness: 2
Luster: Pearly to iridescent

Identified July 26, 2026More gemstone →

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Physical properties

Formation & geological history

Biogenic formation secreted by mollusks (such as pearl oysters, freshwater mussels, and abalone) as an inner shell layer to protect against parasites and debris.

Uses & applications

Widely used in jewelry, decorative inlays for furniture and musical instruments, watch dials, buttons, and ornamental crafts.

Geological facts

Nacre consists of microscopic aragonite tiles stacked in a brick-and-mortar structure glued together by biopolymers, giving it exceptional toughness despite being made of brittle calcium carbonate.

Field identification & locations

Identified by its distinctive multi-colored iridescent sheen (iridescence) that shifts when viewed from different angles. Found worldwide in ocean coastal waters and freshwater lakes/rivers where shell-bearing mollusks live.

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