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]]