Properties of Illite

Illite is a group of non-expanding clay minerals belonging to the mica family. It is a phyllosilicate mineral with a layered structure and is rich in aluminum and potassium.

Image of illite mineral
Credit: DSW 2011, CC BY 3.0, via Wikimedia Commons

The following table provides a comprehensive list of illite properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).

Note: click on the icon to switch between Metric and Imperial units.

Table of Illite Properties
Physical Properties
Metric
Chemical FormulaKAl4[Si7AlO20](OH)4
Crystal SystemMonoclinic
Mohs Hardness1 - 2
Density2800 - 2600 kg/m3
ColorGray white to grayish green
DiaphaneityTranslucent to opaque
LusterWaxy
Cleavage(001) perfect
StreakWhite

Note: unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)

Related Pages
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017.