mineral

Pearl (Biogenic Mineral)

Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3

Hardness: 2.5 - 4.5; Color: Cream, white, pinkish-peach; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific Gravity: 2.60 - 2.85

Hardness: 2
Color: Cream, white, pinkish-peach
Luster: Pearly (iridescent)

Identified April 21, 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: Cream, white, pinkish-peach; Luster: Pearly (iridescent); Crystal structure: Orthorhombic (microcrystalline); Cleavage: None; Specific Gravity: 2.60 - 2.85

Formation & geological history

Formed biogenically inside the soft tissue (mantle) of a living shelled mollusk. It is created as the mollusk deposits layers of calcium carbonate around an irritant. While not 'geological' in a traditional sense, pearls are classified as organic minerals (mineraloids).

Uses & applications

Primarily used in jewelry making (necklaces, earrings, rings) and as a collector's gemstone. Historical uses also include cosmetic powders and traditional medicines.

Geological facts

Known as the birthstone for June. Unlike traditional gemstones mined from the earth, pearls are the only gems found inside a living creature. Natural pearls are extremely rare; most on the market today are 'cultured'.

Field identification & locations

Identify by the 'tooth test' (rubbing against teeth reveals a gritty texture, whereas fakes are smooth). These specific specimens appear to be freshwater cultured pearls due to their slightly irregular (near-round to baroque) shapes and peach-pink overtones.

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