An edge site is a binding site located on a non-basal (edge) surface of a clay mineral.
Cf., binding site

In classic soil mechanics, effective stress of a saturated clay body is the difference between the total stress and the pore water pressure. However, at the microscopic scale, effective stress must consider the actual stress involving forces transferred through particle contacts. In the stress range of interest to soil engineers, both water and soil particles are assumed incompressible, and hence the soil properties and mechanical behavior are controlled by forces involving inter-particle contacts only.

In geology, the weathering process where salt laden ground water is brought to the surface of a geologic material by evaporation, allowing the dissolved salts (e.g., halite, gypsum, calcite, natron) to crystallize forming a white/grey, often fluffy powder. Efflorescence is common in arid climates where rocks or soils of marine origin are exposed at or near the surface.

See ganophyllite.

See “deweylite”.

A 2:1 modulated phyllosilicate having an ideal chemical composition of KM₂₀Si₃₂O₇₆(OH)₁₇, where M = Fe²⁺, Mg, Mn²⁺. Analyses show that Ca and Na substitutes for K, Fe³⁺ substitutes for M, and Al substitutes for Si. Ekmanite has a highly disordered layer-stacking. The proposed model (Ferrow et al, 1999), based on TEM analysis, has strips of tetrahedra attached to the continuous octahedral sheet, with the strips along the a axis. The basic layer is 2:1 with inverted tetrahedra linking across the interlayer through apical oxygen atoms, with three of eight tetrahedra linking the 2:1 layers and inverted relative to adjacent octahedral sheets, similar to bannisterite. All tetrahedral rings are 6-fold, unlike bannisterite. Ekmanite is known from the magnetite ore body and skarns at Brunnsjögruvan, Sweden, in rocks metamorphosed to greenschist facies.

A descriptive term for tenacity where an applied force deforms a crystal, but the crystal resumes its original shape after the applied force is released.
Cf., flexible, brittle

General sets of properties that describe a response of a material to elastic stress. Elastic properties are described by the modulus of elasticity (Young’s modulus), bulk modulus (modulus of incompressibility), and the modulus of rigidity (ì). In the elastic regime, the induced strain is linearly proportional to the stress.
Cf., bulk modulus, Young’s modulus.

For atoms or molecules, an electric dipole occurs where there is a separation of positive and negative charge over a short distance. For example, an electric dipole occurs for H₂O where (the bent) molecule forms a small negative charge near the oxygen atom whereas an equal, but positive charge forms on the opposite side of the molecule associated with the hydrogen atoms.

See diffuse double layer.