pyrolusite


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Related to pyrolusite: pyrrhotite, psilomelane

pyrolusite

(pī`rōlo͞ozīt), naturally occurring manganese dioxide, MnO2, a black mineral that crystallizes in the tetragonal system but is usually found in earthy or massive deposits. It is the principal source of manganese and its compounds, and it is extensively used in steel smelting and in the manufacture of dry-cell batteries. The main producing countries are Russia, Brazil, South Africa, Gabon, India, China, and Australia.

Pyrolusite

 

(also polianite), a mineral with chemical composition MnO2; contains 55–63 percent Mn. Pyrolusite crystallizes in the tetragonal system and has a rutile-type crystal structure. It rarely occurs in the form of thin columnar or acicular crystals. Most often it forms cryptocrystalline, powdery, or earthy masses combined with manganese and iron hydrous oxides, as well as with SiO2, BaO, and H2O. Pyrolusite is gray or black and has a submetallic luster. Ordinary pyrolusite has a hardness of 2–3 on Mohs’ scale, while the crystallized varieties have a hardness of up to 6. The mineral’s density varies from 4,700 to 5,080 kg/m3.

Pyrolusite is found in lacustrine or marine deposits, where oxygen is available; often commercially valuable deposits are formed. The mineral occurs in the oxidation zones of manganese deposits and in certain hydrothermal deposits.

The pyrolusite contained in manganese ores, together with psilomelane and other minerals, is used in the smelting of fer-romanganese. Pure pyrolusites are used in the manufacture of dry-cell batteries and chemical preparations and in glassmaking, porcelain manufacture, and other industries.

pyrolusite

[‚pī·rə′lü‚sīt]
(mineralogy)
MnO2 An iron-black mineral that crystallizes in the tetragonal system and is the most important ore of manganese; hardness is 1-2 on Mohs scale, and specific gravity is 4.75.
References in periodicals archive ?
The ore-bearing porphyry in this sub-district is brecciated and shot through with stringer veins and isolated pods (called Trumern) of manganese oxides, including good pyrolusite ore; the greatest ore concentrations reached 12 meters thick.
Very small crystals occur as crusts on goethite pseudomorphs after siderite (Jahn and Bahmann, 2000); however, recent observations suggest that this bright silver mineral is in fact pyrolusite and not hematite.
In addition, some good pyrolusite crystals were collected there in an oxidized part of the deposit.
Typical black dendrites, presumably pyrolusite, are locally common on bedding surfaces of thin, pale brown, fissile shale exposed in the upper benches of the northern pit.
Pyrolusite is a relatively common late-stage alteration product of Mn-bearing primary carbonates in the limonite ores, found mainly as compact masses up to 30 cm in diameter.
Pyrolusite in black powdery masses and coatings occurs in small quantities at the Bor pit and in the Verchniy, Nikolaevskiy and Second Sovietskiy mines.
Most of these are very good and some are outstanding, especially the big Cornwall bournonite, the miniature of green muscovite from North Carolina, the matrix analcime from the Phoenix mine, Michigan, and a German pyrolusite and German whewellite.
Minerals found in these veins, where they outcrop, are quartz, tourmaline, rhodochrosite, calcite, pyrite, marcasite, galena, sphalerite, chalcopyrite, argentite, pyrolusite and psilomelane.
It also occurred as groups of thin plates in close association with masses of well-crystallized pyrolusite, as thin plates penetrating nodules of hydrocerussite, and as small spheres up to 2 mm embedded in mendipite.
Other minerals which have been mentioned in the literature as occurring in the Picos de Europa, and which we have in some cases observed, are: native mercury (Andara), malachite (La Hermida, Hozarco), willemite (Andara), pyrolusite (Linares), quartz (Linares, Hozarco), gypsum (Aliva, Hozarco), chalcocite and covellite (Hozarco), azurite (Hozarco), and an unverified report of native silver in the La Hermida gorge.
What is probably pyrolusite, in its most typical occurrence as black dendrites, is exposed locally on joint and fracture surfaces of the footwall carbonate rocks on the northwest corner of the 5,175 bench.
3+]O(OH) Magnetite [Mathematical Expression Omitted] Massicot PbO Pyrolusite [Mn.