mineral

Pearl

Calcium carbonate (CaCO3) in the form of Aragonite or Calcite

Hardness: 2.5–4.5; Color: White, cream, pink, silver, gold, black; Luster: Pearly (nacreous); Crystal structure: Orthorhombic aragonite; Cleavage: None; Specific Gravity: 2.60–2.85

Hardness: 2
Color: White, cream, pink, silver, gold, black
Luster: Pearly (nacreous)

Identified April 25, 2026More mineral →

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Physical properties

Hardness: 2.5–4.5; Color: White, cream, pink, silver, gold, black; Luster: Pearly (nacreous); Crystal structure: Orthorhombic aragonite; Cleavage: None; Specific Gravity: 2.60–2.85

Formation & geological history

Formed biogenically inside the soft tissue of a living shelled mollusk or other animal as a response to an irritant (organic process).

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a decorative gemstone. Crushed pearl is also used in cosmetics and traditional medicines.

Geological facts

Pearls are the only gemstones produced by living creatures. The most famous pearl, 'La Peregrina', was owned by Mary I of England and Elizabeth Taylor.

Field identification & locations

Identify by the 'tooth test' (gritty feel against teeth) or looking for a slight iridescent glow (orient). Commonly found in oyster or mussel beds in salt or freshwater.

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