A regular interstratification of dioctahedral mica-like layers and dioctahedral smectite-like layers in a ratio of 1:1 (Brown and Weir, 1963). The structure may be described more completely as pairs of dioctahedral 2:1 layers with alternate interlayers that are mica-like and montmorillonite-like. Mica-like layers may be paragonite-like and the smectite-like layers may be beidellitic. The non-swelling mica interlayers contain about 0.85 univalent cations per mica formula unit and the swelling interlayers about 0.35 univalent cations (e.g., Na, K, but divalent Ca is known also) per smectite formula unit (Bailey, 1982). In the older literature, the name “allevardite” has been used (Bailey, 1982), but the term rectorite has priority.

See hollandite.

an albite-like mineral with B in the tetrahedral site, Na(Si3B)O8. Cf., alkali feldspar, feldspar, plagioclase feldspar

An albite-like mineral with B in the tetrahedral site, Na(Si₃B)O₈.
Cf., alkali feldspar, feldspar, plagioclase feldspar

See hydrotalcite group.

A refractory material retains its chemical and physical properties at high or very high temperatures (ASTM, v. 15.01 indicates high temperature at >1,000^oF). The high- temperature materials are generally non-metallic and are commonly composed of, but not limited to, oxides of aluminum, calcium, magnesium, and silicon. Refractory materials are common in linings for furnaces, kilns, and incinerators, and are used in some crucibles. Fire clays are often used to manufacture refractory materials.
See fire clay

Crustal material above unweathered bedrock, including unweathered rock where it is entirely surrounded by unconsolidated or weathered natural material. The term is not related to the geologic age of the bedrock, the individual constituent materials of the regolith, or the formation or assembly of the ensemble of constituent materials.

An industrial term referring to dehydration of untreated, porous clay until it contains between ~5 – 20 wt % free moisture, with dehydration achieved by heating below or near the boiling point of water (< 105°C) to preserve the integrity of the clay and to create empty pore spaces so that the material may resorb fluids.

The reincorporation of (OH) groups from water (suspension) or air (humidity) into the structure of a clay mineral, previously lost during dehydroxylation.
Cf., dehydroxylation

Literally means “the reach back”. The expression of both the probability of finding a B layer after an A layer in a two-component system of layers containing A and B layers, and the influence A has on the identity of the next layer, after Jadgozinski, 1949. When flipping a coin, R is equal to 0 because there is no influence at all of one flip on another. The probability of getting a head depends only on the proportion of heads and tails, in this case 0.5, and thus there is a null relation between the influence of A on B. For perfect order of 50% I (illite) and 50% S (smectite) layers, ISISIS… the R = 1. A sequence of ISII… is R = 3, with one S layer surrounded by three I layers. Common usage is R0 for R = 0, R1 for R = 1, etc.