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 ?
During the 19th-century heyday of mining the so-called "Ilfeld-Mangan" mine area in Silberbachtal (one of the few workings to have received its own name) measured 2.1 million square meters, and produced chiefly pyrolusite and hausmannite ore from irregular stringers and pods (Rumscheidt, 1926).
The Pyrolusite ore from Cao Bang province, Northern Vietnam, contains approximate 4.7% of iron calculated from amount of [Fe.sub.2][O.sub.3].
2) at Jordan Mountain contains manganite intergrown with pyrolusite, and reduced amounts of hausmannite and psilomelane (Rose and Johnson 1990; Merlini 1998).
Other minerals known to occur include gypsum, lignite/peat, soapstone, lateritic iron ore (250-300 Mt with 35% Fe), mica, pyrite, barytes, copper (malachite and azurite), manganese (pyrolusite) and uranium and, according to studies carried out on behalf of the Direction General de Recursos Minerales (DGRM), some of these mineral commodities could be developed commercially given more favourable economic circumstances.
construction of a CMU operations bullding, inline booster system, 400 gpm pyrolusite treatment system, modifications to the existing Junction I 00,000 gallon reservoir, and all other associated sire work, piping, and electrical as shown on the Drawings and defined in the Specifications.
Among several possibilities (e.g., hausmannite, manganite, and pyrolusite) birnessite and feitknechtite forms are more likely to be formed.
[gamma]-Mn[O.sub.2] possesses a varying structure and composition, with the De Wolff disorder intergrowth of ramsdellite (1 x 2 tunnel) and pyrolusite (1 x 1 tunnel) [6].
Just two days before the Main Show closed, Les Presmyk of De Natura (www.denatura.net) latched onto eight flats of interesting specimens of pyrolusite from an unspecified, long-inactive mine near Las Cruces, New Mexico, and promptly split the lot 50-50 with Rob Lavinsky of Arkenstone.
X-ray diffraction indicates that pyrolusite is the main Mn phase in the areas examined in the sedimentary rocks of the Carboniferous Basin.
Polished section determinations indicate that ore assemblage is composed of hematite and pyrolusite, whilst quartz and calcite are the gangue minerals.
Pseudomorphs of goethite after siderite appeared later in 2000, associated with small struvite and/or ilmenorutile and pyrolusite crystals.
Manganese is more difficult to remove than iron, oxidizing more slowly and requiring longer detention in the basin and sometimes special precipitants, or prefiltration through a coke or pyrolusite contact filter, before sand filtration.