mineral

Natural Pearl

Calcium carbonate (primarily Aragonite and Conchiolin), CaCO3

Hardness: 2.5-4.5 (Mohs); Color: White, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic; Specific Gravity: 2.60-2.85

Hardness: 2
Color: White, pink, silver
Luster: Pearly (iridescent)

Identified June 9, 2026More mineral →

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Physical properties

Hardness: 2.5-4.5 (Mohs); Color: White, pink, silver; Luster: Pearly (iridescent); Crystal structure: Orthorhombic; Specific Gravity: 2.60-2.85

Formation & geological history

Formed organically within the soft tissue of a living shelled mollusk as a defense mechanism against irritants. While not a rock in the traditional sense, they are classified as organic minerals (biogenic gems).

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a traditional gemstone. Historically used in cosmetics and medicine in powdered form.

Geological facts

Pearls are the only gemstones made by living creatures. The rarest pearls are natural (wild) pearls, as most on the market today are cultured by humans.

Field identification & locations

Identify by the 'tooth test' (feeling a slightly gritty texture when rubbed against teeth) and observing the unique orient/iridescence. Commonly found in saltwater oysters and freshwater mussels.

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