hectorite

Hectorite is a magnesium lithium smectite clay mineral in the trioctahedral subgroup of the phyllosilicate group. Its approximate chemical formula is (Mg,Li)3Si4O10(OH)2·nH2O. Like other smectites, hectorite has a 2:1 layered structure consisting of silicate tetrahedral sheets joined by an octahedral sheet; isomorphic substitution within the layers yields a net negative charge that is balanced by exchangeable interlayer cations, typically sodium, lithium, or other cations, and water molecules. The presence of Li and Mg in the octahedral sheet characterizes it as a lithium-bearing, magnesium-rich member of the smectite family. The mineral forms as fine, platy particles that swell when hydrated, giving high surface area and colloidal properties.

Natural occurrence: Hectorite occurs in various geologic environments, including hydrothermally altered ultramafic rocks and clay-rich sediments. It has been described in several countries, with notable deposits in the western United States. The name derives from the Hector mine region in California, where it was first described.

Uses and applications: Natural hectorite is used as a thickener and rheology modifier in drilling muds, cosmetics, paints, and polishes. Synthetic hectorite, sold under trade names such as Laponite, is widely used as a rheology modifier and stabilizer in nanocomposites, cosmetics, inks, and polymer formulations. Its fine platelet morphology and high swelling capacity contribute to its performance as a multifunctional additive.