sedimentary

Kaolin (China Clay)

Kaolinite [Al2Si2O5(OH)4]

Hardness: 2-2.5 (Mohs scale); Color: White, grayish, or yellowish; Luster: Dull to earthy; Crystal Structure: Triclinic; Cleavage: Perfect; Specific Gravity: 2.6

Hardness: 2-2
Color: White, grayish, or yellowish
Luster: Dull to earthy

Identified July 18, 2026More sedimentary →

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Physical properties

Hardness: 2-2.5 (Mohs scale); Color: White, grayish, or yellowish; Luster: Dull to earthy; Crystal Structure: Triclinic; Cleavage: Perfect; Specific Gravity: 2.6

Formation & geological history

Formed by the chemical weathering of aluminum silicate minerals like feldspar in granite. It is found in large sedimentary deposits or primary residual deposits where granite has decomposed.

Uses & applications

Extensively used in ceramics, papermaking, cosmetics, rubber, and as an industrial filler or coating agent.

Geological facts

The name 'Kaolin' is derived from the Chinese word 'Gaoling', meaning 'high ridge', referencing the hill in Jiangxi province where it was historically mined.

Field identification & locations

Identified in the field by its soft, earthy texture, bright white color, and the fact that it forms a plastic paste when mixed with water. Found worldwide in regions with significant granite weathering.