Pearl (Biogenic Mineral)

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.

Identified on: 4/21/2026

Mode: Standard