An obsolete term for paragonite.

An obsolete term for brammallite.

An obsolete term for aspidolite.

In soil science, plasma refers to fine-grained (too fine to resolve individual constituents by visible-light microscopy) crystalline or amorphous materials in soils, which includes saprolites.
Syn. pedoplasma
See saprolite, clay groundmass

In soil science, describing soil formed in place by in-situ weathering of rock parent material.
Cf., clay (sedimentary).

Isostructural phases that show a compositional variation whereby one or more ions can substitute at a specific atomic site in a crystal structure. In fact, the ions can also be elements or ionic groups, and it is possible that more than one atomic site may be involved. A common type of “substitutional solid solution series” shows a miscibility between two end members, with permissible variations in composition between these two end members. For example, olivine (Mg,Fe)₂SiO₄, represents a chemical variation (i.e., solid solution) between two end members, forsterite Mg₂SiO₄ and fayalite Fe₂SiO₄, where Mg and Fe can substitute for one another in two atom sites. The chemical formula may be written as Mg_2-xFe_xSiO₄, where x represents the Fe content, and this value can vary between 0 and 2.0. Other types of solid solutions include “interstitial solid solution” where atoms may reside in interstices between the ideal locations of the atoms of a structure and “omission solid solution” where a site is incompletely filled. “Limited solid solutions” may occur where the compositional variation does not range entirely between the two end members. In addition, two or more substitutions (“coupled substitutional solid solution”) may occur over multiple sites so that the requirement of overall charge neutrality in a phase is satisfied, for example, where Na⁺ + Si⁴⁺ substitute for Ca²⁺ + Al³⁺ in the plagioclase feldspar structures between end members albite, NaAlSi₃O₈, and anorthite, CaAl₂Si₂O₈.

A process of mass transfer where atoms, ions or molecules move through a solid.
Cf., absorbent, adsorbate, cation exchange

In a phase diagram, the solidus describes the upper limits where only solid phases exist.
Cf., liquidus, phase diagram

Unprocessed clay samples commonly contain soluble salts, including chlorides, sulfates, and carbonates, which should be removed either prior to analysis or prior to drying or firing. Such salts can inhibit deflocculation, and they may interfere with the determination of particle size. In addition, they may prevent the preferred orientation of clay-mineral aggregates in preparation for some X-ray analysis procedures. During drying, soluble salts migrate to the clay body surface and can interfere with glazing; after firing, these salts can cause efflorescence.

A generic term for materials displaying a high degree of absorptive and/or adsorptive physicochemical properties, often useful in consumer or industrial applications.