A disorder involving the eating of material that does not have nutritional value. Pica is the more general term for the eating of odd things, such as clay, ice, hair, starch, etc.
Cf., geophagy
A disorder involving the eating of material that does not have nutritional value. Pica is the more general term for the eating of odd things, such as clay, ice, hair, starch, etc.
Cf., geophagy
An obsolete varietal term for a fibrous to columnar form of green serpentine, often referring to antigorite. The original locality is from Taberg, Sweden, and this material was shown to be carlosturanite. The material from Bare Hills, Maryland, USA, was called baltimorite and is considered an obsolete term also.
An obsolete varietal term for magnesian muscovite.
A property of crystals where an electric moment forms in proportion to tension or compression, with a reversal in polarity depending on the direction of the stress. The phenomenon is dependent on certain non-polar crystal classes or symmetries of the material. A “converse piezoelectric” effect is known where the crystal changes shape if an electric current is applied along the polar axis. Quartz exhibits piezoelectric and converse piezoelectric effects.
A clinopyroxene (monoclinic, C2/c space group) with a chemical composition of (Mg,Fe,Ca)(Mg,Fe)Si2O6 where Ca is between about 5 to 15 mole % of CaSiO3 (wollastonite component). Pigeonite forms where the basaltic melt is relatively quickly cooled in, for example, minor shallow intrusions.
See pillared clay.
A clay mineral intercalated with small organic or inorganic complexes (or “pillars”), which do not completely fill the interlayer space. The size and shape of the resultant cavities (or “galleries”) are determined by the size, shape, and orientation of the pillars. Pillared clays are potentially useful to remove organic molecules based on shape-selective adsorption (“molecular sieves”). For clays, intercalations involve positively charged complexes (either organic or inorganic “cations”) to offset the negatively charged layers of the clay. Common types of complexes include those of the methylammonium group (organic) and the Keggin ion (Al13, inorganic). Other types of layered materials can also be pillared.
See Keggin ion.
Cf., zeolite
A kerolite-like phase where Ni > Mg.
Not a valid mineral species, but is often used to describe Ni-rich, 2:1 layer silicates with additional structural H2O.
Cf., kerolite
An obsolete term for nontronite.