See astrophyllite group.

An obsolete varietal term for celadonite.

See corrensite and chlorite/smectite.

A clay that can sorb large amounts of water and thereby expands in volume. The swelling clay minerals, smectite and vermiculite, if they occur as fine-grained material, are referred to as “swelling clays”. In industry, bentonites are commonly referred to as “swelling clay”. Some clays that are referred to as “swelling clays” have been shown to be dominated by clay minerals characterized by interstratifications of two varieties of phyllosilicate layers, one being expandable via adsorption of H₂O and one not, as in “swelling chlorite” which is interstratified chlorite and smectite.
Syn., expandable clay
Cf., swelling clay mineral

A clay mineral that can sorb large amounts of water and thereby expands in volume. Both vermiculite and smectite are swelling clay minerals.
Cf., swelling clay.

Swinefordite is the Mg- and Li-rich trioctahedral member of the smectite group, with the original workers (Tien et al., 1975) determining that the location of Li of the natural sample was split with ~33% in the interlayer and the remainder in the octahedral sheet, and with vacancies in the octahedral site, thereby making this a dioctahedral-trioctahedral intermediate. Köster (1982) redetermined the chemistry based on the cation exchange capacity and determined the composition to be (M⁺_0.4 ^. nH₂O)(Li_1.06Al_0.99 Mg_0.7Fe³⁺_0.10)_Σ=2.85 (Si_3.87Al_0.13)O₁₀(OH)₂ where M is the exchangeable cation and n is variable. The M (interlayer) cation is assumed here as univalent, but it may have other valence states also. The vacancy content in the octahedral site (0.15) is consistent with other trioctahedral smectites (Güven, 1988). Swinefordite occurs as a pseudomorph after spodumene.
Cf., hectorite

Is used to describe an object with a systematic repetition of features, and is particularly useful to describe crystal shapes or atom locations in an object.

Material formed contemporaneously with rocks that are associated or enclose material.

A geometrically fixed intergrowth between two phases. Originally defined as between two polymorphs only and extended to include an oriented intergrowth between any two phases.
Cf., epitaxy, topotaxy

A region of space within the universe. Systems are considered in thermodynamic or other studies to determine how a change in the environment (e.g., temperature changes, pressure changes, etc.) will affect the system. Systems may be closed by encapsulating in noble metals, placing a liquid in a sealed beaker, etc. A “closed system” is affected only by receiving energy from or giving energy to the outside environment. An “open system” differs from a closed system by an exchange of matter, in addition to energy. An “isolated system” receives neither matter nor energy across the boundary.