NOVELTY - Preparing a clay comprises (a) dissolving a salt containing a cation comprising aluminum, magnesium, calcium, zinc, manganese, iron and/or copper and an anion comprising chloride, sulfate, bicarbonate, carbonate, phosphate, monohydrogen phosphate and/or acetylacetonate in a solvent to obtain a mixture, (b) adding at least one functional silane compound to the mixture obtained from the step (a) and (c) adding a strong base to the mixture obtained from the step (b) under agitation at a temperature of lower than 40 degrees C.    USE - The clay is useful as: a surfactant (preferred), ion exchanger, flocculating agent, thickener or adsorbent and a matrix of grafting molecule or a composition of molecules having a chemical activity (all claimed); and in the fields of chemistry, cosmetic, pharmacy, paintings, oil, cements, plant health, agriculture and environment.    ADVANTAGE - The method is capable of rapidly and economically preparing the clay with good physicochemical properties and excellent reproducibility in an environmentally friendly manner.    DETAILED DESCRIPTION - Preparing a clay comprises (a) dissolving a salt containing a cation comprising aluminum, magnesium, calcium, zinc, manganese, iron and/or copper and an anion comprising chloride, sulfate, bicarbonate, carbonate, phosphate, monohydrogen phosphate and/or acetylacetonate in a solvent to obtain a mixture, (b) adding at least one functional silane compound to the mixture obtained from the step (a), and (c) adding a strong base to the mixture obtained from the step (b) under agitation at a temperature of lower than 40 degrees C, where the functional silane compound has a structure of formula ((R)m-Si-(X)p) (I).    X = Cl or 1-4C-alkoxy;    R = a group of acetoxy, alkyl, amine, aminoalkyl, aryl, diaminoalkyl, epoxy, fluoroalkyl, glycol, mercapto, silicic acid ester, silyl, ureide, vinyl or vinylalkyl;    p = 2-4; and    m = 0-2, where the sum of p and m is 4.    An INDEPENDENT CLAIM is included for the clay obtained by the method.