mineral

Pearl

Calcium Carbonate (primarily Aragonite and Calcite), CaCO3

Hardness: 2.5 - 4.5; Color: White, silver, cream, black, or pink; Luster: Pearly (iridescent); Crystal structure: Orthorhombic/Hexagonal; Cleavage: None; Specific gravity: 2.60 - 2.85

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

Identified April 21, 2026More mineral →

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Physical properties

Hardness: 2.5 - 4.5; Color: White, silver, cream, black, or pink; Luster: Pearly (iridescent); Crystal structure: Orthorhombic/Hexagonal; Cleavage: None; Specific gravity: 2.60 - 2.85

Formation & geological history

Biogenic formation within the soft tissue (mantle) of living shelled mollusks; formed when an irritant is trapped and coated with layers of nacre. Age varies by harvest, typically taking several years to grow.

Uses & applications

Predominantly used in jewelry, fashion accessories, and as a collectible gemstone.

Geological facts

Pearls are the only gemstones produced by living organisms; the oldest known pearl jewelry dates back to around 4,200 years ago found in a sarcophagus of a Persian princess.

Field identification & locations

Identify by the 'tooth test' (feels gritty against teeth) and the presence of nacreous luster. Commonly found in tropical and subtropical marine waters or freshwater rivers depending on the species.

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