Initially, an industrial or commercial term, designating calcium bentonite from Mississippi, USA. This material exhibits characteristics of low water adsorption, dilation, viscosification and high green-sand binding strength. Use of the term has broadened to include any bentonite having performance characteristics equal to that of high quality calcium bentonite from Mississippi. Whereas the term “Southern Bentonite”, and its synonyms, continue to have meaning in the industrial and commercial realm, they are scientifically obsolete and should not be used in that context.
Syn: Mississippi Bentonite

The symmetry used to describe a three-dimensional crystal structure, including both translation-free symmetry operators, translational symmetry (i.e., screw axes and glide planes), and Bravais lattices. There are 230 space groups. In mineralogy, Hermann-Mauguin symbols are used, whereas in chemistry and spectroscopy, Schoenflies symbolism is used to characterize the different combinations of symmetry elements.

A dimensionless physical parameter used to measure the relative density of solids, including minerals and soils. Specific gravity is the ratio of the unit weight (or density) of a solid to the weight (or density) of an equal volume of water at 4^oC.

The study of the interaction of radiation with matter.

A poorly described material, possibly a mica related to tainiolite.

A drying technique used in clay science primarily to minimize preferential orientation of clay mineral particles for analysis by X-ray diffraction methods. Spray drying involves high dispersion of a solid (i.e., clay), usually suspended in ethanol or a water-soluble organic binder (i.e., Polyvinyl Alcohol 72,000), where the binder is subsequently evaporated. Although effective, the process usually involves large sample sizes (typically grams). In industrial applications, spray drying is used to economically produce commercial quantities of dried clay having a controlled aggregate particle size, from a liquid clay suspension, without the need for mechanical grinding.

In thermodynamics, a state function is one that is not dependent on the path (i.e., history) that the system has undergone and is only dependent on the state of the system as determined by temperature, pressure, volume, etc. at a particular moment.

An obsolete term for muscovite.

Helmholtz and later Stern divided the solution side of a diffuse double layer into an inner part (Stern or Helmholtz layer) and an outer part (Gouy or diffuse layer). In a more simple model, the ions with a finite size “d” adsorb on a surface and form a so-called outer Helmholtz plane. In the so-called triple layer model, the Helmholtz plane is subdivided into an inner Helmholtz plane (iHp, where specifically adsorbed ions such as protons or K on high-charged clay minerals reside) and an outer Helmholtz plane (oHp, where non-specifically adsorbed ions reside). Note that for all models the following equation holds:
Sigma_zero + Sigma _iHp + Sigma_oHp + Sigma_diffuse = zero.
where: Sigma_zero denotes the charge density (in Coulomb per square meter) of the solid, Sigma_iHp denotes the charge density of species adsorbed in the inner Helmholtz plane (usually specifically adsorbed ions), Sigma_iHp denotes the charge density of species adsorbed in the outer Helmholtz plane (usually nonspecifically adsorbed species), and Sigma_Diffuse is the charge density of the diffuse double layer formed in the solution.
See diffuse double layer

Stevensite is a trioctahedral smectite with an ideal composition of (M⁺_2y ^. nH₂O) (Mg_3-y v_y) Si₄O₁₀(OH)₂ where M is the exchangeable cation in the interlayer (given here as univalent), v represents y vacancies, and n is variable. Stevensite is poorly defined, but the lack of Al, some octahedral vacancies, the high Si content, and the high Mg content are important characteristics. Brindley (1955) described the stevensite structure as two-layer with talc and saponite interstratifications, Faust et al. (1959) suggested that stevensite is a defect structure with two components of talc and talc-like domains, and Shimoda (1971) found stevensite to be composed only of swelling components like smectite minerals. Christidis and Mitsis (2006) studied a Ni-rich stevensite that appeared to confirm the smectite character of one layer type with turbostratic stacking and ethylene glycol intercalation capabilities. Stevensite has been shown to commonly alter from sepiolite, and a Ni-rich stevensite is reported from a supergene alteration of an ophiolite complex in Greece. A significant Al content would allow such a phase to be defined as saponite.