Infobox mineral
name = Pyrolusite
category =
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caption = Pyrolusite Mineral with Dendrite (height of sample ~9 cm)
formula = manganese dioxide, MnO2
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 =
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fusibility =
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var1 = Polianite | var1text = Massive crystals of the very pure form

Pyrolusite is a mineral consisting essentially of manganese dioxide (MnO2) 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 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 (permanganates) 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, and black colors to glass, pottery, and bricks; and in the manufacture of green and violet paints.

Variations in crystal habit

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  • PYROLUSITE — De formule Mn2, la pyrolusite est un oxyde naturel de manganèse. Elle est une pseudomorphose de l’acerdèse MnO(OH) dont elle dérive par déshydratation, le minéral devenant friable et tachant les doigts de noir. La pyrolusite s’observe en masses… …   Encyclopédie Universelle

  • Pyrolusite — Pyr o*lu site, n. [Pyro + Gr. ? to loose, or ? a loosing.] (Min.) Manganese dioxide, a mineral of an iron black or dark steel gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen at a red heat, and is extensively used in …   The Collaborative International Dictionary of English

  • pyrolusite — manganese dioxide, the name given in Roman times, when it was used, in a heated state, to decolorize glass, from Greek elements pyro by heat, by fire (see PYRO (Cf. pyro )) + lysis a loosening (see LOSE (Cf. lose)) …   Etymology dictionary

  • pyrolusite — [pī΄rō lo͞o′sīt΄, pī räl′yo͞osīt΄] n. [Ger pyrolusit < Gr pyr, FIRE + lousis, a washing (< louein, to wash < IE base * lou , to wash > LATHER) + Ger it, ITE1: used, when heated, to remove color from glass] a very soft, black,… …   English World dictionary

  • pyrolusite — /puy reuh looh suyt, puy rol yeuh suyt /, n. a common mineral, manganese dioxide, MnO2, the principal ore of manganese, used in various manufactures, as a decolorizer of brown or green tints in glass, and as a depolarizer in dry cell batteries.… …   Universalium

  • pyrolusite — piroliuzitas statusas T sritis chemija apibrėžtis Mineralas. formulė MnO₂ atitikmenys: angl. pyrolusite rus. пиролюзит …   Chemijos terminų aiškinamasis žodynas

  • pyrolusite — noun Etymology: German Pyrolusit, from Greek pyr + lousis washing, from louein to wash more at lye Date: 1828 a soft black or steel gray mineral of metallic luster consisting of manganese dioxide that is the most important ore of manganese …   New Collegiate Dictionary

  • pyrolusite — noun A dark coloured mineral, consisting of manganese dioxide (MnO), that is an important ore of manganese …   Wiktionary

  • pyrolusite — py·ro·lu·site …   English syllables

  • pyrolusite — py•ro•lu•site [[t]ˌpaɪ rəˈlu saɪt, paɪˈrɒl yəˌsaɪt[/t]] n. mir a grayish black mineral, manganese dioxide, MnO2, the principal ore of manganese • Etymology: 1820–30; pyro + Gk loûs(is) washing + ite I …   From formal English to slang