A measure of the unequal distribution of negative (electrons) and positive (protons) charge in an atom, molecule, or solid, with units of charge times distance (1 Debye, 1 D = 3.335641*10^-30 C.m = 10^-10esu, where esu = electrostatic valency units). A molecule has a nonzero dipole moment if the individual bond dipole vectors do not cancel (e.g., a water molecule).
Cf., polarization

Not a valid term, previously used as a classification of the micas where the number of silicon atoms per formula unit is two per four tetrahedral sites, see Rieder et al. (1998).
Cf., mica, true mica, brittle mica, interlayer-deficient mica, group names

See line defect.

See suspension.

An obsolete varietal term for clintonite.

See microfabric, clay.

A member of the chlorite group, with an ideal formula of (Al_4+x/3Si_4-xAl_x)O₁₀(OH)₈, where x represents excess Al. Both octahedral sheets are dioctahedral, therefore this is a di,dioctahedral chlorite.
Cf., chlorite

See double metal hydroxides.

See double metal hydroxides.

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