See organophilic, organoclay.

A characteristic property of a clay whereby the clay repels an organic liquid. Most naturally occurring clays are organophobic and are not wetted by nonpolar organic liquids.
See organoclay
Cf., organophilic

A trioctahedral member of the true mica group. The end-member, ideal formula is KLi₂Ti⁴⁺Si₄O₁₀(O,F), and orlovite occurs as the 1M polytype. Orlovite is from the Darai-Pioz alkaline massif of the Garmskii district, northern Tajikistan. Ti occurs in two positions in what is normally the M1 site in a mica (the M1 site is typically on a center of symmetry, but in orlovite each of the positions is displaced along the m plane away from the center) separated by 0.432 Å, indicating short range order where Ti is occupied in one domain in one of these positions and in the other domain by the other (Sokolova et al., 2018). Charge balance to offset the 4+ charge of the Ti cation occurs by the substitution of an oxygen anion for fluorine.

See reyerite group.

See alkali feldspar.

A pyroxene subgroup of Mg-Fe pyroxenes in the enstatite-ferrosilite solid-solution series with orthorhombic (Pbca, Pbcn) symmetry. See pyroxene group for additional details.
Cf., enstatite

See crystal system.

A physical process by which a solvent (typically, water) diffuses through a semi-permeable membrane (a porous material which is permeable to the solvent, but not the solute), owing to differences in solvent activity of two solutions which are separated by the membrane.

The differential pressure exerted by a solvent across a semi-permeable membrane owing to the difference in solvent activity between two solutions separated by the membrane.

Interlayer expansion that occurs in phyllosilicate minerals responding to the effects of temperature, pressure and composition (e.g., chemical potential) of an electrolyte surrounding the mineral with respect to the interlayer H₂O (i.e., the “osmotic effect” or “osmotic pressure”). At equilibrium, the chemical potential of H₂O in the electrolyte and in the interlayer is related to the salt concentration of the electrolyte (the osmotic pressure is zero). At a given temperature, pressure, or composition away from equilibrium, there will be a difference in chemical potential between the electrolyte and clay interlayer and the resulting osmotic pressure will be the driving force to affect the layer-to-layer distance. Under certain conditions, the resulting osmotic pressure drives the clay layers further apart than the interlayer distances common to intracrystalline swelling.
Cf., intracrystalline swelling