Kaolin clay
| Kaolinite | |
|---|---|
 |
|
| General | |
| Category |
Phyllosilicates Kaolinite-serpentine group |
|
Formula (repeating unit) |
Al2Si2O5(OH)4 |
| Strunz classification | 9.ED.05 |
| Crystal system | Triclinic |
| Crystal class | Pedial (1) (same H-M symbol) |
| 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 |
| Identification | |
| Color | White, sometimes red, blue or brown tints from impurities |
| Crystal habit | Rarely as crystals, thin plates or stacked, More commonly as microscopic pseudohexagonal plates and clusters of plates, aggregated into compact, claylike masses |
| Cleavage | Perfect on {001} |
| Tenacity | Flexible but inelastic |
| Mohs scale hardness | 2–2.5 |
| Luster | Pearly to dull earthy |
| Streak | White |
| Specific 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 | Measured: 24° to 50°, Calculated: 44° |
| References | |
| Kaolinite | |||||||||||
| Traditional Chinese | 高嶺石 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Simplified Chinese | 高岭石 | ||||||||||
| Literal meaning | "Gaoling stone" | ||||||||||
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| Transcriptions | |
|---|---|
| Standard Mandarin | |
| Hanyu Pinyin | Gāolǐng shí |
| Wade–Giles | Kao1-ling3 shih2 |
| IPA | [káu.lìŋ ʂɨ̌] |
Kaolinite /ˈkeɪəlɪˌnaɪt/ 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 Francois Xavier d'Entrecolles's reports from Jingdezhen.
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