Laponite

Laponite is a synthetic smectite clay invented in 1962 by clay scientist Barbara Neumann. Usually produced as powder, laponite is a nanomaterial made up of very small disk-shaped crystals used in multiple industrial applications. Laponite was first marketed by the company Laporte plc and is currently produced by BYK Additives & Instruments.^{[1][2][3][4][5]} Laponite is not an approved mineral species, since it is not naturally occurring and it is not produced by geological processes.^[6]

In the first formulation of laponite created by Neumann in 1962, the synthetic clay was determined to be a fluorohectorite and was produced in the form of discs 1 nanometer thick and with a diameter of 60 to 80 nanometres. This went into mass production in 1964.^[7] The mineral structure of the clay gives laponite its particular physical characteristics and is similar to the smectite group of clay minerals, with a 2:1 layered crystal structure in which two tetrahedral silica sheets lie either side of an octahedral sheet containing magnesium ions.^[5] In 1966, Neumann patented a second formulation of laponite, called 'Laponite RD'. This form was free from fluorine, and has subsequently become the most widely used form of laponite.^[8] This form of laponite has an empirical formula of Na_0.7[(Si₈Mg_5.5Li_0.3)O₂₀(OH)₄].^[5] In later years, Neumann also created other variants of laponite including a lithium-free magnesium silicate clay, a form of synthetic stevensite, and an iron silicate clay, which was a synthetic form of nontronite.^[7]