Manganite

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manganite

[′maŋ·gə‚nīt]
(mineralogy)
MnO(OH) A brilliant steel-gray or black polymorphous mineral; crystallizes in the orthorhombic system. Also known as gray manganese ore.

Manganite

 

a mineral of the oxide and hydroxide class. It has a chemical composition of MnO(OH) and contains 80.66 percent MnO; admixtures of Fe, Al, Ba, Pb, Cu, and other elements are sometimes present. Manganite crystallizes in the monoclinic system, forming prismatic steel-gray pseudoorthorhombic crystals with a submetallic luster and perfect cleavage. It generally occurs as black or brown (hydromanganite) finely crystalline masses. Concretions and oolitic formations are also widespread. Manganite is brittle. It has a hardness of 3-4 on Mohs’ scale and a density of 4,200-4,330 kg/m3.

Manganite, along with other manganese oxides (pyrolusite, psilomelane), enters into the composition of large sedimentary manganese ore deposits that are formed in the littoral zones of marine basins under conditions of some oxygen deficiency. Manganite also occurs in hydrothermal vein deposits in association with calcite, quartz, barite, and, sometimes, rhodochrosite. It is converted into sooty cryptocrystalline pyrolusite during surface oxidation. Manganite serves as an important source material in the manufacture of ferromanganese and other manganese alloys required for the smelting of special steels.

REFERENCE

Mineraly; spravochnik, vol. 2, fasc. 3. Moscow, 1967.
References in periodicals archive ?
Dagotto, "Nanoscale phase separation and colossal magnetoresistance, the physics of manganites and related compounds," springer-verlag, vol.
Puri, "Studies on rod shaped bismuth strontium manganite ceramics," Science of Advanced Materials, vol.
The world's finest crystal specimens of manganite came from small manganese workings near the town of Ilfeld (the type locality) at intervals between ca.
Ounadjela, "Electron localization in mixed-valence manganites," Physical Review Letters, vol.
This demonstrates that these manganites are "soft" ferromagnets, comparable to the very soft amorphous ferromagnets (42).
The discovery of the colossal magnetoresistance (CMR) effect in epitaxial thin films of [Ln.sub.1-x][R.sub.x]Mn[O.sub.3] perovskite manganites, where R is alkaline earth elements and Ln is rare-earth element, gives an effect for usage in data storage and sensing application [1, 2].
von Molnar, "Mixed-valence manganites," Advances in Physics, vol.
Specific topics covered include structural and electron-hopping studies of Pr- and Nd-substituted manganites, recrystallization annealing of cold-rolled ferritic steel containing silicon, quantitative concepts for morphological stability analysis of solid/liquid interface in rapid solidification of dilute binary alloys, and studies of the spin Hamiltonian parameters for NiX2 and CdX2:Ni2+.
Tokura, "Current switching of resistive states in magneto resistive manganites," Nature, vol.
Rotter et al., "Magnetoelastic investigations at [Pr.sub.1-x][Ca.sub.x]Mn[O.sub.3] (x = 0.35, 0.5) manganites," Journal of Magnetism and Magnetic Materials, vol.
The physical properties of these perovskite manganites are mostly investigated in a bulk form, single crystal [6], and thin or thick film [7].
The aim of this paper is to understand the multiferroic hexagonal manganites studied by some optical techniques.