See tobermorite.

The Zn-rich, platy serpentine defined ideally as Zn₃(Si,Al)₂O₅(OH)₄. Cu, Al, and vacancies are known to substitute for Zn. Occurrences include Gleeson, Arizona, USA, and Laurion, Greece (both Cu-rich), Defiance, Belgium, and Tsumeb, Namibia.

An intermediate structure between chlorite and brittle micas (Peacor et al., 1988). The franklinfurnaceite structure is similar to chlorite-IIa-1 polytype with a trioctahedral 2:1 layer, but with a dioctahedral interlayer (thus, tri-dioctahedral). It differs from chlorite and is more mica-like because Ca cations occupy octahedral sites between the tetrahedral sheets and the dioctahedral interlayers. Franklinfurnaceite is ideally Ca₂Fe³⁺Mn²⁺₃Mn³⁺[Zn₂Si₂O₁₀](OH)₈ and occurs at Franklin, New Jersey, USA.

The Mn analogue of stilpnomelane.
See stilpnomelane

An obsolete term for muscovite.

A free-swell test is a process- or quality-control test to measure the compatibility of a clay with various solvents by placing a specified amount of clay in the fluid of interest, allowing it to remain undisturbed, and by determining the amount of swelling after a specified time. A graduated cylinder is often used to judge the amount of swelling after one or two hours, and 1 gram of clay is typically used, although each manufacturer/supplier follows their own protocols. The test is relative to a clay with no swelling behavior, as there are no standard-swelling behaviors. The test is especially useful to determine the optimum organoclay for paint or grease formulations.

A dehydration process where material is dried via sublimation of contained water. The material is frozen in a vessel, subjected to gas-pressure reduction often followed by slight heating, and dried by removal of sublimated water vapor. In clay mineralogy, samples of clay are dispersed in water as a suspension prior to freeze drying. The residual clay often shows the aggregate structure and fabric of the dispersed phase.

See point defect.

The characteristic of a solid material that allows its particle size to be easily reduced.

See pyrosmalite.