An obsolete term for muscovite.

A trioctahedral member of the brittle mica group. The end-member formula is: BaFe²⁺₃(Fe³⁺Si₃)O₁₀S,OH. Typical site substitutions include: Ba > K,Na; Mg, Fe³⁺, Mn, Al for Fe²⁺; and S > OH,Cl,F. Anandite occurs in a banded magnetite-barite-sulfide ore within meta- sedimentary granulite facies at the Wilagedera iron ore prospect, North Western Province, Sri Lanka, and it has been reported at Rush Creek and Big Creek, Fresno County, California, USA, and Sterling Hill, New Jersey, USA, although the latter occurrences are in doubt because of the lack of structural S, a requirement for the species (Bujnowski et al., 2009). Anandite occurs as 2O and 2M₁ polytypes, and a 2M polytype based on a 1M stacking sub-structure.

A discredited term for kaolinite.

A zone of transition from late diagenesis to low-grade metamorphism. The anchizone is defined by Kübler indices between 0.42 and 0.25 in mudrock lithologies.
Cf., diagenesis, Kübler index

See plagioclase feldspar.

A non-SI unit of measurement equal to 10^-10 meters, e.g., 1 Å = 0.1 nm.

A term referring to a group of clay minerals containing (often brucite-like) layers that have a net positive structural charge and linkage of the layers by way of an anionic (negative) interlayer. The “clay” aspect refers to a (natural) fine-grained material that under appropriate water content will exhibit plasticity and will harden when dried or fired. The term “anionic clay” has the potential for confusion because both anions and cations are structural components. More traditional swelling clays, like smectite or vermiculite, have silicate layers linked by interlayers containing cations, but are generally not referred to as “cationic clays.” More precise and descriptive synonyms are in common usage, and these synonyms may be less confusing, and thus, are preferred over the term “anionic clay”.
Syn., double metal hydroxide, hydrotalcite-like, layered double hydroxide, LDH
Cf., double metal hydroxides

A description of material that has properties (optical, hardness, conductivity, etc.) that differ depending on the direction of measurement. These properties, when related to crystals, are dependent on composition, atomic structure, and structural defects. Nondirectional properties, such as density, also exist. When related to composite materials, such properties may be determined by layering, the properties of the constituent materials, etc.
Cf., isotropy

A discredited manganese oxide mineral better described by the H₂O-free variety of mannardite.
See hollandite

To heat and then cool slowly to reduce internal stress, which commonly involves new grain crystallization toward an equilibrium phase assemblage and texture. Usually relates to glasses and metals.