A member of the palygorskite-sepiolite group with a composition of (K,Na)₅Fe³⁺₇ (Si₂₀O₅₀) (OH)₆ ^. 12(H₂O). The kalifersite shows a regular alternation of structural components of sepiolite and palygorskite Ferraris et al. (1998).
See palygorskite-sepiolite group

An obsolete term for muscovite.

discredited term, use kaolin-serpentine group (Bailey, 1980)

Discredited term, use kaolin-serpentine group (Bailey, 1980).

A name previously proposed for the kaolin/serpentine group. The name has not been approved for use by any mineralogical nomenclature committee and its use should be discontinued.

a) Petrologic term: rock composed primarily of kaolinite, nacrite, dickite, or halloysite (i.e., minerals of the kaolin group). In most case, the identification of the specific species is unknown. The rock is commonly white, earthy, and soft.

b) Mineralogic term: a sub-group name (within the group “serpentine-kaolin”) for those phyllosilicates that are dioctahedral, with 1:1 layers, and with a net layer charge of approximately 0.0. Species of this sub-group include kaolinite, nacrite, dickite and halloysite. Previously, the group name was “serpentine-kaolinite”, and the subgroup name was “kaolinite”, but this scheme created confusion because it was unclear if “kaolinite” was referring to the more general sub-group or the species “kaolinite”.
See also Part 2 of the Glossary.
Cf., dioctahedral, 1:1 layers

A white to gray clayey-textured rock predominantly composed of kaolin group minerals (primarily kaolinite). Hard kaolin is fine grained, difficult to break, and commonly with sharp, protruding (jagged) edges. Hard kaolin requires more complex mine extraction and mineral processing techniques than “soft kaolin” (kaolin-rich rock that is smooth to the touch, weak, and friable).

A member of the kaolin group (1:1 layer, dioctahedral), and polymorphic with dickite and nacrite. The chemical composition is Al₂Si₂O₅(OH)₄. In kaolinite, the vacant octahedral site is located in the “B” site in each layer to form a triclinic structure. 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 (Bish and Von Dreele, 1989). Kaolinite forms under diagenetic and hydrothermal conditions, and may transform to dickite at higher temperatures. At very high temperatures, kaolinite transforms to “metakaolinite”. In early publications, kaolinite was used as the group name, now known as kaolin.
Cf., dickite, halloysite, kaolin, nacrite

Superceded by kaolin subgroup.

Superceded by kaolin-serpentine group.