mineral

Pearl

Calcium carbonate (CaCO3) - Aragonite/Calcite variety

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

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

Identified April 27, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

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

Formation & geological history

Biogenic formation within the soft tissue (mantle) of a living shelled mollusk. It is formed by concentric layers of nacre around an irritant.

Uses & applications

Primarily used in jewelry (necklaces, earrings, rings) and as a decorative gemstone.

Geological facts

Pearls are the only gemstones created by living animals. Notable historical specimens include 'La Peregrina,' which was owned by Mary I of England and Elizabeth Taylor.

Field identification & locations

Identify by the 'tooth test' (feels gritty against teeth) or by observing nacre layers under magnification. Found in both freshwater and saltwater environments globally.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral