An obsolete varietal term for biotite.

Hausmannite, Mn₃0₄, is tetragonal and has a deformed cubic spinel structure. Each Mn cation (Jarosch, 1987) in octahedral coordination is affected by Jahn-Teller distortions with two long Mn-O distances and four short distances. The Mn-O₄ tetrahedra have equal Mn-O bond lengths. Hausmannite is isostructural with the Fe₃O₄ inverse spinel structure (magnetite). Hausmannite occurs in metamorphic manganese deposits, for example at Langban, Sweden, and Postmasburg, South Africa.

Clay used therapeutically, for example, to alleviate pain, absorb toxins, reduce swelling, or protect skin. Common healing clays are montmorillonite (in bentonite), palygorskite/sepiolite, and kaolin.
Cf., active principle, aesthetic medicine, antibacterial clay, geotherapy, medicinal clay, pelotherapy

A measure of the heat energy required to raise the temperature of a substance by 1^oC. For example, the specific heat energy or capacity is the amount of heat needed to raise 1 gram of a substance by 1^oC. The heat capacity is, therefore, equal to the mass of the substance times the specific heat. Thus, the molar heat capacity is the heat capacity per mole.

The energy (often heat) required to transform a given quantity of a solid to a melt without changing temperature.
Cf., heat of sublimation, heat of vaporization

The energy (often heat) required to directly transform a given quantity of a solid to a gas without changing temperature (or going through the liquid state). The heat of sublimation is the sum of the heat of fusion and heat of vaporization at the given temperature.
Cf., heat of vaporization, heat of fusion

The energy (often heat) required to transform a given quantity of a liquid into a gas or vapor without changing temperature.
Cf., heat of sublimation, heat of fusion

Hectorite is the Mg- and Li-rich trioctahedral member of the smectite group. It has the ideal chemical composition of (M⁺_y . nH₂O)(Mg_3-yLi_y)Si₄O₁₀(OH)₂ where M is the exchangeable cation, y is the Li content, and n is variable. The M (interlayer) cation is assumed here as univalent, but it may have other valence states also. F substitution for (OH) has been documented. Stacking of natural samples is generally turbostratic. Fluorohectorite, with M = Na, K, Rb, and Cs and with y = 0.5 was synthesized by Breu et al. (2003), and the well-ordered, one-layer structure of the Cs phase was determined (space group C2/m, 1M polytype).
Cf., swinefordite

A clinopyroxene (monoclinic space group C2/c) with an end-member formula of CaFeSi₂O₆. Hedenbergite and diopside, CaMgSi₂O₆, form a continuous solid solution series. Hedenbergite primarily occurs in metamorphic rocks and skarns.
See pyroxene group for additional details.

See Stern layer.