Kaolinite

Physical Properties
Chemical formula Al2Si2O5(OH)4
Class Phyllosilicate
Crystal system Triclinic
Habit Usually massive or fine-grained aggregates
Platy, pseudohexagonal (rare)
Color White
Hardness 2 to 2.5
Specific gravity 2.6
Cleavage/fracture Perfect (001) but rarely seen
Luster Waxy
Pearly
Dull
Earthy
Transparency Sometimes translucent
Streak White
Optical Properties
δ 0.007
after Perkins 318-319

Kaolinite in Hand Sample

Kaolinite

Reddish sillimanite in white kaolinite

Kaolinite in Thin Section

Stay tuned!

Further Reading

Kaolinite at webmineral.com

Kaolinite at mindat.org