a) unglazed ceramic that has undergone firing;
b) the dried, but not yet fired, enamel coating. The bisque firing temperature is that initially used to stabilize the ceramic prior to glazing.
Syn., biscuit
a) unglazed ceramic that has undergone firing;
b) the dried, but not yet fired, enamel coating. The bisque firing temperature is that initially used to stabilize the ceramic prior to glazing.
Syn., biscuit
A trioctahedral member of the brittle mica group. The end-member formula is: CaLiAl2(BeAlSi2)O10(OH)2. Compositional range restriction includes viLi > vi□, where □ = vacancy (i.e., viLi < vi□ is defined as margarite). Bityite forms in the 2M1 polytype and has been found in pegmatites from Madagascar, Zimbabwe, and the Urals, and in a tin vein in Uganda. Like margarite, bityite (Lin and Guggenheim, 1983) has nearly complete tetrahedral ordering of Al,Be vs Si, and thus is non-centric in symmetry (Cc space group).
Cf., margarite
Bixbyite, alpha-(Mn3+,Fe3+)2O3, is structurally comprised of edge sharing and corner sharing (Mn,Fe)O6 octahedra. Bixbyite has been reported from non-metamorphosed sediments where it had transformed from todorokite-birnessite, and from hydrothermal and low grade metamorphic deposits.
Used in decolorizing oil products, typically fuller’s earth or bentonite, by adsorption. For example, bleaching earth is used to remove the green color of chlorophyl in some cooking oils.
Syn., bleaching earth
A processing term used in industry to describe the high-energy mixing or disaggregation of clay (or a similar substance) into water to form a uniform slurry (i.e., suspension or slip) for use in ceramics or paper making. A blunger usually consists of a round or octagonal tank with a mixer-impeller attrition blade. Post-blunging slurry processing may be performed to separate and concentrate the clay mineral phase or remove grit and heavy minerals, via wet sieve, hydrocyclone, flotation, gravity separation, chemical modification and/or magnetic separation.
See suspension, grit
Boehmite, or gamma-AlO(OH), is a hydrous aluminum oxide comprised of corrugated sheets of double edge-sharing octahedra of Al–O,OH. Boehmite is isostructural with lepidocrocite, the Fe analogue. Bauxite is a mixture of diaspore, gibbsite, and boehmite, and any one of the three may dominate.
Syn., böhmite
See boehmite.
An obsolete term for a greasy clay with iron oxide impurities that produce a red, yellow and/or brown color and with about 24% water, possibly primarily halloysite.
Syn. “bergseife” for “mountain soap”, also obsolete
Born repulsion forces are described as a strong, short-range repulsion term for bond energy between two charged ions. Born repulsion forces arise when neighboring ions approach sufficiently close so that the electron clouds involving the inner electron orbitals begin to overlap, thereby forcing higher energy states owing to the Pauli exclusion principle. The term increases exponentially as orbital interpenetration increases with the decrease in interionic distance.
A boron-rich member of chlorite with an ideal chemical composition of Li1+3xAl4-x(BSi3)O10(OH,F)8 where x = 0.0 to 0.33 atoms per formula unit (Zagorsky et al., 2003). Borocookeite occurs as the Ia polytype. Borocookeite has been found in miarolitic cavities at temperatures greater than 240-265oC in pegmatite deposits, such as in the Krasny Chikoy district, Chita region, Russia.
Cf., manandonite, boromuscovite