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Kaolinite is a cley meeneral, pairt o the group o industrial meenerals, wi the chemical composeetion Al2Si2O5(OH)4.

Category Phyllosilicates
Kaolinite-serpentine group
(repeatin unit)
Strunz clessification 09.ED.05
Creestal seestem Triclinic
Space group Triclinic pedial
H-M seembol: (1)
Space group: P1
Unit cell a = 5.13 Å, b = 8.89 Å, c = 7.25 Å; α = 90°, β = 104.5°, γ = 89.8°; Z = 2
Colour White, sometimes reid, blue or broun tints frae impurities
Creestal habit Rarely as creestals, thin plates or stacked, Mair commonly as microscopic pseudohexagonal plates an clusters o plates, aggregatit intae compact, cleylik masses
Cleavage Perfect on {001}
Tenacity Flexible but inelastic
Mohs scale haurdness 2–2.5
Skinkle Pearly tae dull yirdy
Streak White
Speceefic gravity 2.16–2.68
Optical properties Biaxial (–)
Refractive index nα = 1.553–1.565,
nβ = 1.559–1.569,
nγ = 1.569–1.570
2V angle Measurt: 24° to 50°, Calculatit: 44°
References [1][2][3]


  1. "Kaolinite mineral information and data". Retrieved 2009-08-05. 
  2. "Kaolinite Mineral Data". Retrieved 2009-08-05. 
  3. Kaolinite in the Handbook of Mineralogy