Kaolinite
Al2Si2O5(OH)4IMA symbol: Klnapproved
Kaolinite is a silicate mineral with the formula Al2Si2O5(OH)4, crystallizing in the triclinic system. It has a Mohs hardness of 2-2.5, typically white, brown, gray or red in color, with a dull or earthy luster, a specific gravity of 2.6-2.63. Its streak is green.
Photos
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Crystallography
| Crystal system | triclinic crystal systemWikidata (CC0) |
|---|---|
| Space group | C 1 |
| Cell (Å, °) | a = 5.1528, b = 8.9415, c = 7.3985; α = 91.715, β = 104.756, γ = 89.866 |
| Cell volume | 329.482 ų, Z = 2 |
| Source structure | COD 9017767 (Minerals, 2020) — 1 of 6 structures |
Physical properties
| Hardness (Mohs) | 1single sourceWikidata (CC0) 2-2.5single sourceDana, System of Mineralogy, 6th ed. (1892) |
|---|---|
| Specific gravity | 2.6-2.63 g/cm3single sourceDana, System of Mineralogy, 6th ed. (1892) |
| Color | brown, gray, red, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892) |
| Streak | whitesingle sourceWikidata (CC0) greensingle sourceDana's System, 2nd Appendix (1909) |
| Luster | dull, earthy, pearlysingle sourceDana, System of Mineralogy, 6th ed. (1892) |
Chemistry (calculated)
| Molecular weight | 258.16 g/molcalculated from the IMA formula |
|---|---|
| Composition (wt%) | Al 20.9%, Si 21.76%, O 55.78%, H 1.56% |
Classification
| Nickel-Strunz (10th) | 9.ED.05Wikidata (CC0) |
|---|---|
| Nickel-Strunz (9th) | 9.ED.05Wikidata (CC0) |