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.
A trioctahedral member of the true mica group. The end-member formula is KFe2+3Fe3+Si3O10(OH)2 and the known polytype is 1M. The ferri-iron component is found in the tetrahedral site. Tetra-ferri-annite is commonly associated with stilpnomelane. Stilpnomelane, when coexisting with tetra-ferri-annite, often appears to be replaced by tetra-ferri-annite. Therefore, tetra-ferri-annite occurs in very low-grade metamorphosed iron formations.
A trioctahedral member of the true mica group. The end-member formula is KMg3Fe3+Si3O10(OH)2, and the occurrence of tetra-ferriphlogopite is from Al-poor, ultrabasic magmas under oxidizing (typically late-stage) environments, such as in alkaline-carbonatites and in some mica kimberlites. Tetra-ferriphlogopite occurs as a 1M polytype.
See crystal system.