mineral
Kaolinite (China Clay / Chalky Claystone)
Al2Si2O5(OH)4
Hardness: 1.5–2.0 on the Mohs scale. Color: Off-white, pale tan, beige, or light grey. Luster: Dull, earthy, soft appearance. Structure: Triclinic (microcrystalline masses). Very soft and powdery to the touch.
- Hardness
- 1
- Color
- Off-white, pale tan, beige, or light grey
- Luster
- Dull, earthy, soft appearance
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Physical properties
Hardness: 1.5–2.0 on the Mohs scale. Color: Off-white, pale tan, beige, or light grey. Luster: Dull, earthy, soft appearance. Structure: Triclinic (microcrystalline masses). Very soft and powdery to the touch.
Formation & geological history
Formed by the chemical weathering or hydrothermal alteration of aluminum silicate minerals like feldspar, commonly found in granitic rock settings.
Uses & applications
Extensively used in the production of ceramics, porcelain, paper coating, rubber, cosmetics, and paints.
Geological facts
Kaolinite is named after Kao-Ling village in Jiangxi Province, China, where it was mined for centuries to produce fine porcelain.
Field identification & locations
Identified in the field by its very low hardness (scratched easily by a fingernail), soft chalky feel, earthy dull luster, and pale color. Found abundantly worldwide in weathered clay deposits.
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