Properties of Vermiculite

Vermiculite is a naturally occurring mineral that undergoes significant expansion when heated. It is a member of the phyllosilicate group of minerals and is characterized by its ability to expand into a lightweight and highly absorbent material when subjected to high temperatures.

Image of vermiculite mineral
Credit: James St. John, CC BY 2.0, via Wikimedia Commons

The following table provides a comprehensive list of vermiculite 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 Vermiculite Properties
Physical Properties
Metric
Chemical Formula(Mg,Ca)0.7(Mg,Fe,Al)6[(Al,Si)8O20](OH)4·8H2O
Crystal SystemMonoclinic
Mohs Hardness1.5 - 2
Density2300 kg/m3
ColorColorless, white, yellow, green, brown, black
DiaphaneityTranslucent
LusterGreasy, vitreous
Cleavage{001} perfect

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.