view crystal in whole frame

Kaolinite [Al2Si2O5(OH)4]

Structure Triclinic
Space Group C1
a=5.1400 Å, b=8.9300 Å, c=7.3700 Å
a=91.80, b=104.50, g=90.00
Z=1

Atomic Positional Parameters

O1  4a 0.7780  0.1800 -0.1400
O2  4a 0.2780  0.3200 -0.1380
O3  4a 0.3160 -0.0080 -0.1360
O4  4a 0.2480  0.1840  0.1550
O5  4a 0.7540  0.3150  0.1550

O6  4a 0.6900  0.0040  0.1570
O7  4a 0.7910  0.1650  0.4820
O8  4a 0.6120 -0.1200  0.4550
O9  4a 0.1080 -0.0580  0.4550
Al1 4a 0.5020  0.1720  0.0030

Al2 4a 0.0020  0.3300  0.0020
Si1 4a 0.8000  0.3220  0.3820
Si2 4a 0.8000  0.0000  0.3850
Hydrogens not located in unit cell

Reference
VA Drits and AA Kashaev (1960)
Kristallografiya, 5, 224

Mineral Chemistry
The kaolinite structure consists of a Si2O5 sheet bonded on one side to a (dioctahedral) gibbsite-type layer. The gibbsite-type layer consists of aluminiums coordinated by hydroxyl groups, with some hydroxyls replaced by the oxygens of the Si-O sheet.

Kaolinite is a secondary mineral resulting from weathering or hydrothermal alteration of alumino-silicates such as feldspars and feldspathoids. Chemical compositional variation in kaolinite is limited.

The CHIME figure shows aluminiums as grey spheres, oxygens as red spheres, silicons as ochre spheres, and hydroxyl groups as blue spheres. The unit cell is outlined.