An obsolete term for tobelite.

A term describing a non-crystalline phase where the constituent components (i.e., atoms, ions, molecules) are without long-range order, i.e., not related by translation periodicity. There are many variations of such order or lack of order, for example, glasses commonly occur where atoms are arranged as coordination groups of tetrahedra (e.g., four oxygen ions in coordination about a silicon ion). Such tetrahedra share vertices to define local structure similar to that of crystalline phases; however, such groups of atoms are not related by long-range translation periodicity. This type of short-range order is much different than a simple random positioning of atoms. Amorphous character can be described by the nature of the analysis, e.g., such that the material may produce an X-ray diffraction pattern without discrete maxima, hence, “X-ray amorphous”.
Cf., non-crystalline, crystalline

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.

See crystal.

See ion.