An obsolete term for celadonite, ferrian celadonite.

An obsolete term for a Cr-containing chlorite from the Ural mountains.

A poorly defined material, probably not a mica.

Kübler (1964, 1967) attempted to define a “crystallinity” index for illite (“IC”) by examining the powder X-ray diffraction of intergrown illite and muscovite, originally to identify the anchizone (diagenesis) and the anchizone-epizone (metamorphic) boundaries. Measured values are expressed as small changes in the d value based on the width for the 10-Å peak at half height above the background for Cu radiation. If the procedure is used, it should not be characterized as a “crystallinity” index, as it is unclear if “crystallinity” is actually being measured because such patterns also reflect the presence of smectite and other K-rich micas, different mean crystallite sizes, lattice strain, layer stacking order, instrument parameters and other features.
Cf., crystalline, crystallinity index, Hinckley index, Arkai index

A regular interstratification of talc-like layers and trioctahedral (tri,trioctahedral) chlorite in a ratio of 1:1 (Abraham et al., 1980). The ideal formula is Mg₈Al(Si₇Al)O₂₀(OH)₁₀, although substitutions of NaAl = Si to about Si_0.4 are known.

See astrophyllite group.

See plagioclase feldspar.

See lamination.

See microfabric, clay.

Sequences of thin bedding (or “laminae”) occurring because of variations in the sediment supply in sedimentary rocks. Potter et al. (2005) suggests that laminae are <1 cm.