mineral

Kaolinite (Kaolin)

Kaolinite (Al2Si2O5(OH)4)

Hardness: 2.0-2.5 on Mohs scale; Color: Pure white, sometimes stained reddish or yellow; Luster: Pearly to dull earthy; Crystal Structure: Triclinic; Cleavage: Perfect basal cleavage; Specific Gravity: 2.6.

Hardness: 2
Color: Pure white, sometimes stained reddish or yellow
Luster: Pearly to dull earthy

Identified June 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the chemical weathering of aluminum silicate minerals like feldspar in igneous or metamorphic rocks, often in warm, moist climates.

Uses & applications

Used extensively in the production of paper (for gloss), ceramics, porcelain, toothpaste, light bulbs, cosmetics, and as a food additive or medicine (adsorbent).

Geological facts

The name 'Kaolin' is derived from 'Gaoling', a Chinese village where this clay was historically mined for the creation of fine porcelain or 'China clay'.

Field identification & locations

Identified by its soft, plastic feel when wet, an earthy odor, and its ability to be easily scratched with a fingernail. Found in deep weathering crusts or sedimentary basins.