Hectorite

Hectorite is a rare soft, greasy, white, lithium-rich clay mineral with a chemical formula of.
Hectorite was first described in 1941 and named for an occurrence in the United States near Hector, California. Hectorite belongs to the smectite group; it is a swelling 2:1 clay mineral. Hectorite occurs with bentonite as an alteration product of clinoptilolite from volcanic ash and tuff with a high glass content. Hectorite is also found in the beige/brown clay ghassoul, mined in the Atlas Mountains in Morocco. A large deposit of hectorite is also found at the Thacker [Pass lithium deposit], located within the McDermitt Caldera in Nevada. The Thacker Pass lithium deposit could be a significant source of lithium.
Despite its rarity, it is economically viable as the Hector mine sits over a large deposit of the mineral. Hectorite is mostly used in making cosmetics, but has uses in chemical and other industrial applications, and is a mineral source for refined lithium metal.