A group name for naturally occurring and synthetic compounds with the general formula of M²⁺_(1-x)M³⁺_x(OH)₂A^-x where M²⁺ is a divalent metal with Mg being the most common in nature (others include Ni, Cu, Ca Fe), M³⁺ is a trivalent metal normally Al or Fe (also Cr), A^– is a monovalent anion, and x is commonly near 0.3. The most common anion in nature is CO₃^2- [SO₄^2-, Cl^–, (OH)^– also occur]. For divalent anions, the formula is altered to (x/2). The positively charged portion of the structure is brucite-like, with the anion portion analogous to the interlayer in the phyllosilicates. The interlayer materials are readily exchangeable and may include H₂O and occasional cations.
Syn., layer double hydroxides, LDH, double layer hydroxides, hydrotalcite-like group, HT, anionic clay, and various similar versions