In soil science, soil or sand contraction involves the volumetric reduction of a saturated clayey soil or sand body by drained shearing. For a soft, normally consolidated or lightly over consolidated saturated clayey soil subject to drained shearing, pore water generally flows out of the soil (or sand) owing to shearing-induced positive excess pore water pressure, and hence its total volume decreases, indicative of contraction behavior.
Cf., dilation

A Li-bearing member of the chlorite group, with an ideal composition of (Li,Al₄)(Si₃Al)O₁₀(OH)₈. The octahedral sheet of the 2:1 layer is dioctahedral and the interlayer is trioctahedral, therefore this is a di,trioctahedral chlorite. The common polytype is based on the Ia structure.
Cf., chlorite

See zussmanite.

See hollandite.

A regular interstratification of trioctahedral chlorite-like layers with either trioctahedral smectite-like or trioctahedral vermiculite-like layers, the former being “low-charge corrensite” and the latter “high-charge corrensite”. The ratio of chlorite-like layers to smectite-like or vermiculite-like layers is 1:1 (Guggenheim et al., 2006). Corrensite occurrences are from low temperature environments, such as evaporites, saline deposits, sedimentary rocks, weathering zones, hydrothermal systems, burial diagenesis, low grade metamorphic regimes, and some contact metamorphic zones. Beaufort et al. (1997) discussed corrensite possibly as a regular mixed-layer structure involving a continuous series from smectite (or vermiculite) to chlorite or alternatively, as a single phase with a regular alteration of chlorite and smectite (or vermiculite) layers, with a stability field. If the latter, mixtures that deviate from 1:1 ratios of interstratified layers would require physical mixtures of appropriate layers of corrensite and chlorite.

An obsolete term for margarite.

An obsolete term for low-Si (and variable amounts of Fe₂O₃) chlorite.

The United States Federal Food, Drug, and Cosmetic Act (FD&C Act) of 13 March 2013 defines cosmetics by their intended use, as “articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body…for cleansing, beautifying, promoting attractiveness, or altering the appearance” [FD&C Act, sec. 201(i)]. The act specifically excludes soap as a cosmetic. Clays and clay minerals used in cosmetics include bentonite, illite, kaolin, iron oxides, etc., often characterized by color or locality, and each purported to function or behave differently.

An obsolete varietal term for paragonite.

For classical calculations or simulations of atomic structures, Coulomb interactions account for the attraction or repulsion between pairs of atoms in accord with the positive or negative charge on each atom. Coulomb’s Law is used to calculate the potential energy between each pair of atoms in the model system. For periodic systems, the long-range component of these interactions is often treated in reciprocal space by Ewald summation or a similar technique.
Syn., Coulombic interactions, electrostatic interactions;
Cf., Ewald sum, force field