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.

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.