In soil science, soil or sand dilation involves the volumetric expansion of a saturated clayey soil or sand body when subject to drained shearing. For a stiff, highly over consolidated saturated clayey soil subject to drained shearing, pore water may generate a negative pressure and water external to the body tends to flow into the soil (or sand), and hence its total volume increases, indicative of dilation behavior.
Cf., contraction, soil or sand;

A species of the chlorite mineral group with dioctahedral sheets only (e.g., donbassite)
Cf., trioctahedral chlorite, di,trioctahedral chlorite, dioctahedral sheet

In the ideal case, the smallest structural unit in a phyllosilicate contains three octahedra. If two such sites are occupied with cations and one site is vacant, then the octahedral sheet is considered “dioctahedral”. If all three sites are occupied, the sheet is considered “trioctahedral”. (Quot Guggenheim et al., 2006; see also references therein). A dioctahedral sheet generally contains predominantly trivalent cations.
Cf., trioctahedral sheet

A clinopyroxene with an end-member composition of CaMgSi₂O₆. A continuous solid-solution series exists between diopside and hedenbergite, CaFeSi₂O₆. Diopside occurs in metamorphic rocks, alkali basalts, and nodules in kimberlite. Near end-member diopside occurs in metasomatic rocks, such as skarns formed through contact metamorphism between siliceous carbonate and granitic intrusion.
See pyroxene group for additional details

An obsolete term for margarite.

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

An obsolete varietal term for clintonite.

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

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