Illite wani nau'in ma'adinan yumbu ne na mica tare da wadataccen potassium silicate, Hakanan ana kiransa da ruwan fari mica. Formula kamar K0.75 Al1.75 (R) Si3.5 Al0.5 O10 (OH) 2, R = karfe ions, yafi ga bivalent magnesium, ferrous baƙin ƙarfe. Ana nuna shi azaman ɓacin rai a ƙarƙashin microscope na lantarki. Tauri 1-2, babu kumburi kuma babu filastik.
Abubuwan sinadaran
| SiO2 | Farashin 2O3 | Fe2O3 | TiO2 | Babban | MgO | k2o | Na 2O |
| 46.27 | 34.81 | 0.28 | 0.66 | 0.42 | 0.18 | 8.94 | 0.99 |
Na jiki
| Farin fata | Danshi(%) | PH | Yawan yawa (g/cm3) | Girman |
| 78-80 | 0.5max | 7-7.5 | 2.6-2.9 | 800-2000 na ruwa |
