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Superceded by kaolin subgroup.

Superceded by kaolin-serpentine group.

A non-regular interstratification of kaolinite-like layers with smectite-like layers. Alternatively, the smectite-like layer may be replaced with other expandable layers (e.g., vermiculite). Found in paleosols. May be abbreviated K/S or K-S, and has been referred to as an “kaolinite/expandable” interstratification, K/E (Hughes et al., 1993).

A commercial product (made by Chattem, Inc.) involving a formulation of kaolin and pectin that was used as an anti-diarrheal. Since 2003, the formulation was changed to bismuth subsalicylate, but some formulations containing attapulgite as the active principle are sold in Canada.

An aluminum-rich Keggin-type structure is commonly used as a pillaring agent in clays. This complex has a composition of Al₁₃O₄(OH)₂₄(H₂O)₁₂)⁷⁺, and is often referred to as Al₁₃. Other compositions with the Keggin structure are possible, but they have not been as extensively studied in pillared clays. Keggin structures are of commercial interest because they are catalysts.
See pillared clay.

A platy serpentine mineral of ideal composition of Mn₂Al(Si,Al)O₅(OH)₄, and thus, the Mn²⁺ analogue of amesite. Mg and Fe²⁺ have been found to substitute for Mn and Al. Natural occurrences are rare; the type locality is Bald Knob, North Caroline, USA. Stacking disorder is common but, two-layer (2H₂) and six-layer polytypes are known to occur.
Cf., amesite, zinalsite

A temperature unit where one K equals 1/273.16 of the thermodynamic temperature of the triple point of pure water, which is the temperature at which ice, water and water vapor can coexist in thermodynamic equilibrium (definition from the 13th Conference of the Générale des Poids et Mesures). 0 K, termed “absolute zero”, is the temperature at which atoms do not thermally vibrate.
Cf., Celsius, Fahrenheit

See magadiite.

A variety of talc, but with H₂O either in the interlayer or associated with the broken bonds at the edges of the particles. As a variety of talc, “kerolite” should not be used as a mineral name in a strict sense. Brindley et al. (1977) reported the composition as Mg₃Si₄O₁₀(OH)₂ ^. nH₂O with n = 0.8 – 1.2. Stacking is turbostratic and particle size is < 5 layers. After weeks under ethylene glycol, kerolite swells slightly, whereas talc does not. Kerolite occurs in weathering profiles (Brindley et al., 1977), in palustrine environments (Pozo and Casas, 1999), and in microbial mats in Hawaiin caves (Léveillé et al., 2002), and may be derived from sepiolite (Stoessell, 1988). Older literature may use the spelling of “Cerolite”.
Cf., pimelite, talc