Kaolinite

Kaolinite (/ˈkeɪəlɪnaɪt/) is a clay mineral, part of the group of industrial minerals with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6) octahedra. Rocks that are rich in kaolinite are known as kaolin /ˈkeɪəlɪn/ or china clay. Al 2 Si 2 O 5 ( OH ) 4 ⟶ Al 2 Si 2 O 7 + 2 H 2 O {displaystyle {ce {Al2Si2O5(OH)4 -> Al2Si2O7 + 2 H2O}}} 2 Al 2 Si 2 O 7 ⟶ Si 3 Al 4 O 12 + SiO 2 {displaystyle {ce {2 Al2Si2O7 -> Si3Al4O12 + SiO2}}} 3 Si 3 Al 4 O 12 ⟶ 2 ( 3 Al 2 O 3 ⋅ 2 SiO 2 ) + 5 SiO 2 {displaystyle {ce {3 Si3Al4O12 -> 2(3 Al2O3. 2 SiO2) + 5 SiO2}}} 2 Al ( OH ) 3 + 2 H 4 SiO 4 ⟶ Si 2 O 5 ⋅ 2 Al ( OH ) 3 + 5 H 2 O {displaystyle {ce {2Al(OH)3 + 2H4SiO4 -> Si2O5 . 2Al(OH)3 + 5H2O}}} Kaolinite (/ˈkeɪəlɪnaɪt/) is a clay mineral, part of the group of industrial minerals with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO4) linked through oxygen atoms to one octahedral sheet of alumina (AlO6) octahedra. Rocks that are rich in kaolinite are known as kaolin /ˈkeɪəlɪn/ or china clay. The name 'kaolin' is derived from 'Gaoling' (Chinese: 高嶺; pinyin: Gāolǐng; literally: 'High Ridge'), a Chinese village near Jingdezhen in southeastern China's Jiangxi Province. The name entered English in 1727 from the French version of the word: kaolin, following François Xavier d'Entrecolles's reports on the making of Jingdezhen porcelain. Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g). It is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world it is colored pink-orange-red by iron oxide, giving it a distinct rust hue. Lighter concentrations yield white, yellow, or light orange colors. Alternating layers are sometimes found, as at Providence Canyon State Park in Georgia, United States. Commercial grades of kaolin are supplied and transported as dry powder, semi-dry noodle or as liquid slurry. The chemical formula for kaolinite as used in mineralogy is Al2Si2O5(OH)4, however, in ceramics applications the formula is typically written in terms of oxides, thus the formula for kaolinite is Al2O3 · 2SiO2 · 2H2O.