A dioctahedral member of the true mica group. The end-member formula is KAl₂ vAlSi₃O₁₀(OH)₂ (where v = vacancy). Typical range in composition is: Si= 3.0 – 3.1, ^ivAl = 1.9 – 2.0, K = 0.7 – 1.0 (although the interlayer site is defined in true micas as I ≥ 0.85), ^viR²⁺/(^viR²⁺ + ^viR³⁺) < 0.25, ^viAl/(^viAl + ^viFe³⁺) = 0.5 – 1.0 (Rieder et al., 1998). Muscovite commonly occurs in the 2M₁ polytype, and less commonly in 1M, 3T, 1M_d, and 2M₂ forms. Muscovite is a common rock forming mineral and occurs in igneous, metamorphic, diagenetic, and weathering environments.
Cf., nanpingite, paragonite

An obsolete term for preiswerkite.

An obsolete term for preiswerkite.

A member of the kaolin group, which consists of the dioctahedral and aluminous rich 1:1 phyllosilicates. Nacrite has a chemical composition of Al₂Si₂O₅(OH)₄. Nacrite is distinguished from the other polymorphs, kaolinite and dickite, by the vacant octahedral site regularly alternating from layer to layer across “B” and “C” sites and by a different stacking sequence of layers (Zheng and Bailey, 1994). The “B” and “C” sites would be related by a mirror plane if both sites were occupied identically within the same layer, whereas the “A” site resides on the mirror plane. Dickite and nacrite have a similar alteration of vacant sites, but kaolinite does not. Nacrite differs from dickite by the different stacking sequence. In nacrite the stacking is similar to the 6R polytype, but the vacancy produces monoclinic symmetry. The choice of axes produces a two-layer, monoclinic structure. Nacrite is considered the high-temperature kaolin form, occurring in hydrothermal and pneumatolytic environments.
Cf., dickite, halloysite, kaolin, kaolinite

An obsolete term for muscovite.

See astrophyllite group.

See astrophyllite group.

Nanocomposites are fine-particulate materials that are heterogeneous at the nanoscale level (i.e., less than 10-7 meters). Such materials have structures and properties that are composite-particle-size dependent. The composite-particle size is sufficiently large that it is not considered a chemical (atom) cluster or complex.

Nanocomposites are fine-particulate materials that are heterogeneous at the nanoscale level (i.e., less than 10^-7 meters). Such materials have structures and properties that are composite-particle-size dependent. The composite-particle size is sufficiently large that it is not considered a chemical (atom) cluster or complex.

An organoclay with at least one dimension in the nanometer range dispersed in a polymer (e.g. nylon-6 clay-nanocomposites; see Gilman et al.,1997). The less hydrophilic surface of organoclays facilitates dispersion in a polymer. Dispersing ~5% organoclay in a polymer can make the polymer more flame retardant and improve the physical properties.
See Gilman et al., 1997; Picken et al., 2008; Ruiz-Hitzky and Van Meerbeek, 2006.
Cf., organoclay, organoclay microcomposite