In civil engineering, a clayey soil formed by transport and sedimentation of particles by water, air, or ice. Loess is an example of a sedimentary soil because it forms via wind transport and sedimentation. Sedimentary marine clay forms by deposition of fine-grained particles through seawater.
See astrophyllite group.
An obsolete term for celadonite.
An organoclay + organic solvent with an optimum gel strength that has not been augmented by additives, such as polar molecules (e.g., ethyl alcohol, acetone, propylene carbonate).
See gel strength, organoclay
Self-dispersing organoclays are clays that have additives to develop viscosity at much lower shear and energy input than other, non self-dispersing organoclays. An example of additives to form an appropriate complex are EDTA(ethylenediaminetetraacetic acid) and dimethyldihydrgenated tallow quaternary ammonium. This molecule intercalates into the organoclay and props the interlayer open to allow exfoliation.
A geotechnical term that evaluates the degree of strength loss when natural silty-clay and clayey-silt size sediments are thoroughly disturbed by natural or human actions. Sensitivity (St) of sediments is the ratio of the undisturbed in-situ shear strength to the shear strength after thorough remolding. Generally, the higher the sensitivity, the greater the geotechnical challenge, for example, in leading to flow landslides or excessive consolidation.
A member of the palygorskite-sepiolite group with a composition of approximately (Mg8-y-zR3+yvz) (Si12-xR3+x) O30 (OH)4 (OH2)4 . R2+(x-y+2z)2 (H2O)8, where R are cations, v are vacancies, and x, y, and z are compositional parameters.
See palygorskite-sepiolite group
A group name for phyllosilicates with characteristics that are dominantly fiber-like, but with some plate-like character. The atomic structure has continuous planes of basal oxygen atoms (thus forming the plate-like character) with the apical oxygen atoms of the tetrahedra pointing alternatively in opposite directions away from the basal plane. The tetrahedral apices link to partial octahedral sheets, discontinuous along one direction but infinite in the other, to form a pattern of octahedral ribbons (thus forming the dominant fiber-like character). These minerals are classified as modulated phyllosilicates. The width of ribbons may vary, which leads to different numbers of octahedral cation sites per formula unit (5 for palygorskite, 8 for sepiolite).
An invalid term, use kaolin-serpentine group (Bailey, 1980).
A poorly defined term, commonly used in the past to describe an optical microscopic fine-grained aggregate of mica-like phases.