An obsolete term for muscovite.

Originally defined as a regular 3:1 interstratification of (three) dioctahedral mica and (one) smectite layers, but the material is insufficient in regularity to warrant a formal mineral name. The name is in reserve in case a sufficiently regular interstratification of the same type is found.

See astrophyllite group.

A term first used by Schultz (1969) to describe a montmorillonite with the same chemical characteristics of the Chambers-type montmorillonite(i.e., a total net layer charge of -0.85 to -1.20 per unit cell [O₂₀(OH)₄] with a layer-charge contribution from tetrahedral substitutions of between -0.15 to -0.50), but with higher temperatures of dehydroxylation at 710-730^oC rather than at 660-690^oC. Use of this term is obsolete. See Chambers-type montmorillonite. Terms used in this obsolete classification are: Wyoming-type, Otay-type, Chambers-type, Tatatila-type, beidellite-type (ideal and non-ideal), and non-ideal montmorillonite. Current nomenclature for montmorillonite is that it is an Al-rich, dioctahedral smectite with an ideal structural formula of (Al_3.15Mg_0.85)Si₈O₂₀(OH)₄X_0.85.nH₂O with layer charge from primarily octahedral substitutions of Mg.

Glass that has been heat treated in a specific way such that its thermal properties and mechanical strength are improved. This treatment often involves heating to near the glass softening point followed by controlled cooling, resulting in a glass that will break into granular fragments rather than sharp plates. Such glass is also known as “safety glass.”

Resistance to breaking or deforming a crystal.

The maximum stress developed in a material by a pulling load at the point of rupture, given as a load per cross sectional (e.g., kg per cm²).

An obsolete term for a clay of unknown composition resembling halloysite, from Haute-Loire, France.

Unglazed or glazed building blocks of either low- or high-fired clay, typically used as ornamental features on buildings.

A red glaze made from hematite.