Manganese pyrolusite

It is therefore to the vital air [oxygen] of the manganese [pyrolusite], which combines with the marine acid, that the formation of the dephlogisticated marine acid is due. I ought to state that this theory was presented and announced some time ago by M. Lavoisier, and that M. de Fourcroy made use of it in his Elements of Chemistry and Natural History to explain the properties of dephlogisticated marine acid such as they were then known. 

Manganese Pyrolusite Mn02 Russia, Gabon, South Africa... 

Manganese Pyrolusite (Mn02) Reduction of oxide by carbon or aluminum Manufacturing alloys with iron and other metals... 

Manganese is the third most abundant transition metal, and is widely distributed in the earth s crust. The most important ore is pyrolusite, manganese(IV) oxide. Reduction of this ore by heating with aluminium gives an explosive reaction, and the oxide Mn304 must be used to obtain the metal. The latter is purified by distillation in vacuo just above its melting point (1517 K) the pure metal can also he obtained by electrolysis of aqueous manganese(II) sulphate. 

Manganese(IV) oxide is the only familiar example of this oxidation state. It occurs naturally as pyrolusite, but can be prepared in an anhydrous form by strong heating of manganese(II) nitrate ... 

L. magnes, magnet, from magnetic properties of pyrolusite It. manganese, corrupt form of magnesia)... 

Most manganese today is obtained from ores found in Russia, Brazil, Australia, Republic of S. Africa, Gabon, and India. Pyrolusite and rhodochrosite are among the most common manganese minerals. The metal is obtained by reduction of the oxide with sodium, magnesium, aluminum, or by elctrolysis. 

Pyrolusite, see Manganese(IV) oxide Pyrophanite, see Manganese titanate(IV)(2—) Pyrophosphate, see Diphosphate(V)... 

Pyrolusite is a black, opaque mineral with a metallic luster and is frequendy soft enough to soil the fingers. Most varieties contain several percent water. Pyrolusite is usually a secondary mineral formed by the oxidation of other manganese minerals. Romanechite, a newer name for what was once known as psilomelane [12322-95-1] (now a group name) (7), is an oxide of variable composition, usually containing several percent water. It is a hard, black amorphous material with a dull luster and commonly found ia the massive form. When free of other oxide minerals, romanechite can be identified readily by its superior hardness and lack of crystallinity. 

The crystal stmcture of ramsdeUite [12032-73-4] is similar to that of P Mn02 except that double chains of MnO octahedra are cross-Unked to adjacent double chains through the sharing of oxygen atoms located at the corners. RamsdeUite and pyrolusite are the only manganese dioxide phases where the composition approaches the stoichiometric Mn02 formula. Heating ramsdeUite to 250°C transforms it to pyrolusite. 

Metallic manganese was first isolated in 1774 when C. W. Scheele recognized that pyrolusite contained a new element, and his fellow Swede, J. G. Gahn, heated the Mn02 with a mixture of charcoal and oil. The purity of this sample of the metal was low, and high-purity (99.9%) manganese was only produced in the 1930s when electrolysis of Mn solutions was used. 

Braunstsin, m. pyrolusite, manganese dioxide (roter) rhodochrosite (schwarzer) hausman-nite, -blende, /. alabandite. -kies, m. ala-bandite. -kiesela m. rhodonite, -rahm, -schsum, m, bog manganese, wad. braunstichig, a. brownish. 

Manganerz, n. manganese ore. — graues manganite pyrolusite. — schwarzes —, hausrnannite. 

Pyrolusite. Dissolve 1.5-2 g, accurately weighed, pyrolusite in a mixture of 25 mL of 1 1 hydrochloric acid and 6 mL concentrated sulphuric add, and dilute to 250 mL. Filtration is unnecessary. Titrate an aliquot part containing 80-100 mg manganese add 200 mL freshly prepared, saturated sodium pyrophosphate solution, adjust the pH to a value between 6 and 7, and perform the potentiometric titration as described above. 

Manganese Mn, at wt 54.94, brittle, silvery metal, mp 1245°, bp 2097°, d 7,44g/cc, Mohs hardness 5 decomps in w, readily dissolved in dil mineral acids. Usually associated with Fe ores in sub-marginal concns. Important ores of Mn are pyrolusite, manganite, psilomelane rhodochrosite. Prepd by reduction of the oxide with Al or C. Pure Mn is obtained electrolyti-cally from sulfate or chloride sain. It is used, in powd form, in the manuf of delay powds and in some pyrotechnic mixts. The requirements of the USA Armed Forces are covered by... 

A rich supply of manganese lies in nodules of ore that litter the ocean floors (Fig. 16.9). These nodules range in diameter from millimeters to meters and are lumps of the oxides of iron, manganese, and other elements. However, because this source is technically difficult to exploit, manganese is currently obtained by the thermite process from pyrolusite, a mineral form of manganese dioxide ... 

Carl Wilhelm Scheele (1742-1786) discovered chlorine in the reaction of hydrochloric acid with manganese dioxide (pyrolusite or brownstone ore). Recognized as an element by Sir Humphry Davy (1778-1829). 

Manganese dioxide (brownstone or pyrolusite) is used in dry batteries as an oxidizing agent for zinc (as counterelectrode). 

Black Inorganic Pigments Pyrolusite Manganese dioxide... 

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