Pyrolusite 875372 225804370 2008-07-15T14:07:22Z TXiKiBoT 3171782 robot Adding: [[eu:Pirolusita]] {{Infobox mineral | name = Pyrolusite | category = | boxwidth = | boxbgcolor = | image = Pyrolusite Mineral with Dendrite Macro Digon3.jpg‎ | imagesize = | caption = Pyrolusite Mineral with Dendrite (height of sample ~9 cm) | formula = [[manganese dioxide]], MnO<sub>2</sub> | molweight = | color = Darkish, black to lighter grey, somethimes bluish | habit = Granular to massive - botryoidal and dendritic | system = [[Tetragonal]] | twinning = | cleavage = Perfect on 100 and 011 | fracture = Rough | mohs = 2 - 2.5 | luster = Metallic | refractive = Opaque | opticalprop = | birefringence = | pleochroism = None | streak = Same as color | gravity = 4.73 - 4.86 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = | other = | var1 = [[Polianite]] | var1text = Massive crystals of the very pure form }} '''Pyrolusite''' is a [[mineral]] consisting essentially of [[manganese]] dioxide ([[manganese|Mn]][[oxygen|O]]<sub>2</sub>) and is important as an [[ore]] of manganese. It is a soft, black, amorphous appearing mineral, often with a granular, fibrous or columnar structure, sometimes forming reniform crusts. It has a metallic [[Lustre (mineralogy)|luster]], a black or bluish-black streak, and readily soils the fingers. The [[specific gravity]] is about 4.8. Pyrolusite and [[rhodochrosite]] are among the most common manganese minerals. The metal is obtained by reduction of the oxide with [[sodium]], [[magnesium]], [[aluminium]], or by [[electrolysis]]. Pyrolusite is extensively used for the manufacture of [[spiegeleisen]] and [[ferromanganese]] and of various alloys such as manganese-[[bronze]]. As an oxidizing agent it is used in the preparation of [[chlorine]] and disinfectants ([[permanganate]]s) and for decolorizing glass. When mixed with molten glass it oxidizes the ferrous [[iron]] to ferric iron, and so discharges the green and brown tints. As a coloring material, it is used in calico printing and dyeing; for imparting violet, [[amber (color)|amber]] and black colors to glass, pottery and bricks; and in the manufacture of green and violet paints. == Variations in crystal habit == [[Image:Pyrolusite botryoidal.jpg|thumb|184px|left|[[Botryoidal]]]] [[Image:Pyrolusite_dendritic.jpg|thumb|130px|left|[[Dendrite (crystal)|Dendritic]]]] [[Image:Pyrolusite_radiating.jpg|thumb|146px|left|[[wiktionary:acicular|Acicular]] radiating]] {{-}} {{1911}} {{mineral-stub}} {{Manganese minerals}} [[Category:Manganese minerals]] [[Category:Oxide minerals]] [[Category:Rutile group]] [[bs:Piroluzit]] [[de:Pyrolusit]] [[es:Pirolusita]] [[eu:Pirolusita]] [[he:פירולוזיט]] [[hu:Piroluzit]] [[nl:Pyrolusiet]] [[ja:軟マンガン鉱]] [[pl:Piroluzyt]] [[pt:Pirolusita]] [[ro:Piroluzit]] [[ru:Пиролюзит]]