A poorly described term for material from Yanokami Hill, Omi Province, Japan, possibly a kaolin or smectite.

See hydrotalcite group.

Talc is a 2:1 layer silicate and ideally Mg₃Si₄O₁₀(OH)₂ with layers linked via van der Waals interactions (for a summary, see Evans and Guggenheim, 1988). Layer stacking is controlled by the avoidance of Si to Si electrostatic interactions across the interlayer to form a talc-1A polytype (where A = anorthic, older literature refers to this polytype as 1Tc). There are no six- or twelve-fold sites within the interlayer region as in the micas. The talc-2M polytype is poorly crystalline and rare. Talc is commonly near end-member compositions with more major substitutions of Fe²⁺ and more minor substitutions of Al and F, with trace substitutions of Mn, Ti, Cr, and Ni. The mineral willemseite is defined for Ni > Mg. Talc occurs in Mg-rich rocks in metamorphosed ultramafic rocks and siliceous dolomites. Talc has also been rarely reported from evaporites, limestones, in beach sands, low-temperature hydrothermal environments, and seafloor sediments.
Cf., kerolite, pyrophyllite, willemseite

Inappropriate usage for a 2:1 layer.
See layer.

A group name for platy phyllosilicates of 2:1 layer and a layer charge of ~ 0 per formula unit. Generally, the d(001) spacing is approximately 9.1-9.4 Å. The group is further divided into subgroups that are either trioctahedral (talc) or dioctahedral (pyrophyllite), and these subgroups are further divided into mineral species based on chemical composition. The layers are bonded by weak van der Waals interactions.
See “group names”

An obsolete term for muscovite.

Originally defined as a regular 3:1 interstratification of (three) dioctahedral mica and (one) smectite layers, but the material is insufficient in regularity to warrant a formal mineral name. The name is in reserve in case a sufficiently regular interstratification of the same type is found.

See astrophyllite group.

A term first used by Schultz (1969) to describe a montmorillonite with the same chemical characteristics of the Chambers-type montmorillonite(i.e., a total net layer charge of -0.85 to -1.20 per unit cell [O₂₀(OH)₄] with a layer-charge contribution from tetrahedral substitutions of between -0.15 to -0.50), but with higher temperatures of dehydroxylation at 710-730^oC rather than at 660-690^oC. Use of this term is obsolete. See Chambers-type montmorillonite. Terms used in this obsolete classification are: Wyoming-type, Otay-type, Chambers-type, Tatatila-type, beidellite-type (ideal and non-ideal), and non-ideal montmorillonite. Current nomenclature for montmorillonite is that it is an Al-rich, dioctahedral smectite with an ideal structural formula of (Al_3.15Mg_0.85)Si₈O₂₀(OH)₄X_0.85.nH₂O with layer charge from primarily octahedral substitutions of Mg.

Glass that has been heat treated in a specific way such that its thermal properties and mechanical strength are improved. This treatment often involves heating to near the glass softening point followed by controlled cooling, resulting in a glass that will break into granular fragments rather than sharp plates. Such glass is also known as “safety glass.”