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 ?
Behera, "The influence of band jahn-teller effect and magnetic order on the magneto-resistance in manganite systems," Physica B: Condensed Matter, vol.
Puri, "Studies on rod shaped bismuth strontium manganite ceramics," Science of Advanced Materials, vol.
Okamoto, "Detecting charge and lattice dynamics in photoinduced charge-order melting in perovskite-type manganites using a 30-femtosecond time resolution," Physical Review B, vol.
In Figure 4(c) lower intensity in 574.0 [cm.sup.-1] and higher in 654.2 [cm.sup.-1] possibly indicate hausmannite ([Mn.sub.3][O.sub.4]) [29], while higher intensity around 616.5 [cm.sup.-1] in Figure 4(d) suggests manganite (MnOOH) [29].
The last mining activity near Ilfeld ceased in 1922, but the simple statement of Peter Bancroft (1984) that "Manganite is synonymous with Ilfeld" remains true today: this is without doubt the world's best locality for crystal specimens of the black manganese hydroxide.
Recently spin polarized injection has been demonstrated in organic semiconductor OLEDs based on sexithienyl and CMR manganite, [La.sub.2]/3[Sr.sub.1]/3Mn[O.sub.3] (LSMO).
2) at Jordan Mountain contains manganite intergrown with pyrolusite, and reduced amounts of hausmannite and psilomelane (Rose and Johnson 1990; Merlini 1998).
They begin with a substrate of lanthanum manganite, which serves as the cathode, covered with a layer of yttria-stabilized zirconia, which serves as the electrolyte, covered in turn by nickel, which serves as the anode.
The solid oxide is sandwiched between a cathode, made of strontiumdoped lanthanum manganite, and an anode, made of nickel-zirconia cermet.
Features of highly correlated electronic states in the simple perovskite manganite [Sr.sub.1-x][Sm.sub.x]Mn[O.sub.3] with 0.15 [less than or equal to] x [less than or equal to] 0.50.
report a study of lanthanum strontium manganite and show that Sr-rich phases are present [8].
Activity of catalase was determined by a reduction with potassium manganite (VII) of the residue of hydrogen peroxide being a reaction substrate according to Alef and Nannpieri (1998).