a) a process or processes to concentrate an ore mineral. The British equivalent is “mineral dressing”.
b) the process of improving the performance characteristics of an industrial clay by processing and/or the addition of chemical additives, e.g., bentonite.
a) Mineralogical/Petrological term: A soft, plastic, light-colored rock composed primarily of clay minerals of the smectite group, particularly the clay mineral montmorillonite, which typically forms from chemical alteration of glassy volcanic ash or tuff under marine or hydrothermal conditions. Bentonite may contain accessory crystal grains that were originally phenocrysts in the parent rock as well as secondary authigenic mineral phases such as K- rich feldspar. Diagenetic or low-grade metamorphic alteration can modify the smectite to a variety of interstratified illite-smectite minerals, resulting in materials known as K-bentonites.
b) Industrial term: A highly colloidal and plastic clay material, primarily composed of the clay mineral montmorillonite, that is commonly used in drilling mud, as a foundry sand binder, in cat litter, animal feed, cements, ceramics and various other industrial activities and products. Sodium bentonite swells significantly when exposed to water (to ~12X) whereas calcium bentonite has minimal swelling capability (to ~3X).
Cf., tonstein
A generic industrial classification for a white- or nearly white-colored bentonite clay (primarily smectite, illite, and/or interstratifications), generally low in iron-bearing and organic phases, and often containing some kaolin and/or minor silicate accessory minerals (quartz, feldspar, opal, etc.). White bentonite is a common base material for many value-added industrial and consumer applications and products.
See “bole”, halloysite.
A member of the serpentine group with an ideal composition of approximately (Fe2+, Mn2+, Mg)3-x(Fe3+, Al)x(Si2-xAlx)O5(OH)4. Berthierine is commonly found in unmetamorphosed sedimentary iron formations. Berthierine occurs more commonly as either an apparent trigonal (possibly 1T) or less commonly as an apparent monoclinic (possibly 1M) polytype, and both polytypes are generally intergrown. Berthierine is often confused in the older literature with chamosite, a member of the chlorite group, but not to be confused with berthierite, a sulfide mineral.
Cf., brindleyite, chamosite
An obsolete term for muscovite.
See mirror plane.
A double layer of atoms or molecules. In clay science, an example would be an alkylammonium organoclay.
See bilayer, phyllosilicate for an example.
Cf., alkylammonium organoclay bilayer; bilayer, phyllosilicate; monolayer, phyllosilicate
An interlamellar arrangement of two monolayers of alkylammonium cations [each monolayer has a C-C-C plane of the alkyl chain parallel to the (001) plane of the silicate 2:1 layers] between 2:1 layers of a phyllosilicate. The positively charged end groups (e.g., –NH4+) of the alkylammonium cations are attached to the interlayer silicate surfaces to produce a characteristic d value depending on the identity of the alkylammonium cation.
Cf., alkylammonium layer charge method, alkylammonium organoclay, bilayer, monolayer, organoclay