In the context of polymer/clay nanocomposites, a tactoid is any collection of “primary” (i.e., the smallest division of the phyllosilicate particle that retains the chemical character of the compound, either a 1:1 or 2:1 layer), colloidal-size clay particles, which are essentially acting as a unit.

An obsolete term for tainiolite.

See gangue.

A trioctahedral member of the true mica group. The end-member formula is KLiMg₂Si₄O₁₀F₂, and tainiolite occurs as 1M, 2M₁, and 3T polytypes. Tainiolite is found in alkaline and peralkaline rocks, especially syenites and metasomatites.
Syn., taeniolite

See birnessite.

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”