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Pyrolusite

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Pinal Co., Arizona, USA
© 2001 John H. Betts

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Formula:
MnO
 
2
System:TetragonalColour:Black or very dark grey.
Hardness:2 - 6½
Name:Named in 1827 from the Greek for "fire" and "to wash," because it was used to remove brown and green tints in the making of glass.


Rutile Group

Usually found as matte-black powdery to fibrous crusts, sometimes in botryoidal aggregates or columnar, more rarely as druzes of small prismatic to tabular, dark grey metallic crystals.

NOTE: Most supposed specimens of pyrolusite in dendritic form turn out to be other Mn-oxide species (e.g., minerals of the cryptomelane group or todorokite) upon being examined in the proper laboratory setting for characterizing these difficult to identify minerals.

Classification of Pyrolusite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Explanation of status:
Strunz 8th edition ID:4/D.02-20
Nickel-Strunz 10th (pending) edition ID:4.DB.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
B : With medium-sized cations; chains of edge-sharing octahedra
Dana 7th edition ID:4.4.1.4
Dana 8th edition ID:4.4.1.4

4 : SIMPLE OXIDES
4 : AX2
Hey's CIM Ref.:7.18.3

7 : Oxides and Hydroxides
18 : Oxides of Mn
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Occurrences of Pyrolusite

Geological Setting:A common Mn mineral, although difficult to distinguish from similar Mn minerals, pyrolusite forms under oxidizing conditions and high pH. Mainly a mineral of lacustrine, shallow marine, and bog deposits, it is also found in the oxidized zones of manganiferous ore deposits and as deposits formed by circulating meteoric water. Both colloidal processes and bacterial action are important in its formation.

Physical Properties of Pyrolusite

Lustre:Metallic, Dull, Earthy
Diaphaneity (Transparency):Opaque
Colour:Black or very dark grey.
Streak:Black to bluish-black.
Hardness (Mohs):2 - 6½
Hardness Data:Measured
Comment:6 to 6.5 when crystalline, 2 when massive.
Tenacity:Brittle
Cleavage:Perfect
Perfect on {110}.
Fracture:Irregular/Uneven
Density (measured):5.04 - 5.08 g/cm3
Density (calculated):5.189 g/cm3

Crystallography of Pyrolusite

Crystal System:Tetragonal
Class (H-M):4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:P42/mnm (P42/m 21/n 2/m)
Cell Parameters:a = 4.4041(1) Å, c = 2.8765(1) Å
Ratio:a:c = 1 : 0.653
Unit Cell Volume:V 55.79 ų (Calculated from Unit Cell)
Z:2
Morphology:Crystals are uncommon, either long or short prismatic parallel to [001] or equant; more typically found as earthy powder or fibrous aggregates as crusts on rocks; often dendritic on fracture surfaces or enclosed in chalcedony ("moss agate"), sometimes as botryoidal aggregates, more rarely as druzes of microscopic crystals. [The obsolete term "polianite" was once used to refer to crystalline pyrolusite, which was assumed to be a different species than earthy to crusty pyrolusite.]
Twinning:Twinning rare. Repeated twins with twin planes {031} and {032}. Polysynthetic twinning observed in polished sections.
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data: Peaks:
Data courtesy of RRUFF project at University of Arizona, used with permission.
X-Ray Powder Diffraction:
d-spacingIntensity
3.11(100)
2.41(60)
2.11(20)
1.62(60)
1.56(10)
1.306(20)
1.304(20)
Comments:Data given are for synthetic material.

Optical Data of Pyrolusite

Type:Anisotropic
Anisotropism:Strong, in yellows
Colour in reflected light:Cream-white
Pleochroism:Weak
Comments:Very weak. Yellow to yellow gray.

Chemical Properties of Pyrolusite

Formula:
MnO
 
2
Essential elements:Mn, O
All elements listed in formula:Mn, O

Relationship of Pyrolusite to other Species

Related Minerals - Nickel-Strunz Grouping):
4.DB.05Argutite
GeO
 
2
4.DB.05Cassiterite
SnO
 
2
4.DB.05Plattnerite
PbO
 
2
4.DB.05Rutile
TiO
 
2
4.DB.05Tripuhyite
Fe
3+
 
Sb
5+
 
O
 
4
4.DB.05Tugarinovite
MoO
 
2
4.DB.05Varlamoffite
(Sn,Fe)(O,OH)
 
2
4.DB.10Byströmite
MgSb
 
2
O
 
6
4.DB.10Tapiolite-(Fe)
(Fe,Mn)(Ta,Nb)
 
2
O
 
6
4.DB.10Tapiolite-(Mn)
(Mn,Fe)(Ta,Nb)
 
2
O
 
6
4.DB.10Ordoñezite
ZnSb
 
2
O
 
6
4.DB.15Akhtenskite
ε-Mn
4+
 
O
 
2
4.DB.15Nsutite
(Mn
4+
 
,Mn
2+
 
)(O,OH)
 
2
4.DB.15Paramontroseite
VO
 
2
4.DB.15Ramsdellite
Mn
4+
 
O
 
2
4.DB.20Scrutinyite
alpha-PbO
 
2
4.DB.25Ishikawaite
U
4+
 
Fe
2+
 
Nb
 
2
O
 
8
4.DB.25Ixiolite
(Ta,Nb,Sn,Fe,Mn)
 
4
O
 
8
4.DB.25Samarskite-(Y)
(Y,Fe
3+
 
,Fe
2+
 
,U,Th,Ca)
 
2
(Nb,Ta)
 
2
O
 
8
4.DB.25Srilankite
Ti
 
2
ZrO
 
6
4.DB.25Yttrocolumbite-(Y)
Y(U
4+
 
,Fe
2+
 
)Nb
 
2
O
 
8
4.DB.25Calciosamarskite
(Ca,Fe
3+
 
,Y)
 
2
(Nb,Ta,Ti)
 
2
O
 
8
4.DB.25Iwashiroite-(Y)
Y(Ta,Nb)O
 
4
4.DB.25Samarskite-(Yb)
(Yb,Fe
3+
 
)
 
2
(Nb,Ta)
 
2
O
 
8
4.DB.25Písekite-(Y)
4.DB.30Ferberite
FeWO
 
4
4.DB.30Hübnerite
MnWO
 
4
4.DB.30Sanmartinite
(Zn,Fe)WO
 
4
4.DB.30Krasnoselskite
CoWO
 
4
4.DB.35Columbite-(Fe)
FeNb
 
2
O
 
6
4.DB.35Tantalite-(Fe)
FeTa
 
2
O
 
6
4.DB.35Columbite-(Mn)
(Mn,Fe)(Nb,Ta)
 
2
O
 
6
4.DB.35Tantalite-(Mn)
MnTa
 
2
O
 
6
4.DB.35Columbite-(Mg)
(Mg,Fe,Mn)(Nb,Ta)
 
2
O
 
6
4.DB.35Qitianlingite
(Fe,Mn)
 
2
(Nb,Ta)
 
2
WO
 
10
4.DB.35Magnocolumbite
4.DB.35Tantalite-(Mg)
(Mg,Fe
2+
 
)(Ta,Nb)
 
2
O
 
6
4.DB.40Ferrowodginite
FeSnTa
 
2
O
 
8
4.DB.40Lithiotantite
Li(Ta,Nb)
 
3
O
 
8
4.DB.40Lithiowodginite
LiTa
 
3
O
 
8
4.DB.40Titanowodginite
MnTiTa
 
2
O
 
8
4.DB.40Wodginite
Mn(Sn,Ta)Ta
 
2
O
 
8
4.DB.40Ferrotitanowodginite
Fe
2+
 
TiTa
 
2
O
 
8
4.DB.45Tivanite
VTiO
 
3
(OH)
4.DB.50Carmichaelite
(Ti,Cr,Fe)[O
 
2-x
(OH)
 
x
]
4.DB.55Alumotantite
AlTaO
 
4
4.DB.60Biehlite
((Sb,As)O)
 
2
[MoO
 
4
]
Related Minerals - Hey's Index Grouping:
7.18.1Manganosite
MnO
7.18.2Hausmannite
MnMn
 
2
O
 
4
7.18.4Ramsdellite
Mn
4+
 
O
 
2
7.18.5Akhtenskite
ε-Mn
4+
 
O
 
2
7.18.6Feitknechtite
Mn
3+
 
O(OH)
7.18.7Manganite
Mn
3+
 
O(OH)
7.18.8Groutite
Mn
3+
 
O(OH)
7.18.9Nsutite
(Mn
4+
 
,Mn
2+
 
)(O,OH)
 
2
7.18.10Pyrochroite
Mn(OH)
 
2
7.18.11Birnessite
(Na,Ca)
 
0.5
(Mn
4+
 
,Mn
3+
 
)
 
2
O
 
4
 · 1.5H
 
2
O
7.18.12Aurorite
(Mn
2+
 
,Ag,Ca)Mn
4+
3
O
 
7
 · 3H
 
2
O
7.18.13Cianciulliite
Mn(Mg,Mn)
 
2
Zn
 
2
(OH)
 
10
·2-4H
 
2
O

Other Names for Pyrolusite

Synonyms:
Anhydrous Binoxyd of ManganeseFusaGrau BraunsteinGray Oxyd of ManganeseLapis manganensis
Lichtes GraumanganerzManganaise griseManganese DioxideMangan HyperoxydPeroxide of manganese
PolianitePrismatic Manganese-OrePseudomanganiteVarviciteWeichbraunstein
French names:
Acerdèse fibreuse
German names:
PolianitPyrolusitWeichmangan
Italian names:
Pirolusite
Russian names:
Пиролюзит
Spanish names:
PolianitaPyrolusita
Varieties:
Argentiferous Pyrolusite

Other Information

Fluorescence in UV light:None.
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Pyrolusite

Reference List:Dana and Penfield (1888), American Journal of Science: 35: 243.

St. John (1923), Phys. Rev.: 21: 389.

Ferrari (1926), Acc. Linc., Att.: 3: 224.

Vaux (1937), Mineralogical Magazine: 24: 521.

Palache, Charles, Harry Berman & Clifford Frondel (1944), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged: 562-566.

Neues Jahrbuch für Mineralogie, Monatshefte (1974): 8: 371-384.

American Mineralogist (1979): 64: 1199.

Gaines, Richard V., H. Catherine, W. Skinner, Eugene E. Foord, Brian Mason, Abraham Rosenzweig (1997), Dana's New Mineralogy : The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana: 238.

Kohler, T., Armbruster, T., and Libowitzky, E. (1997) Hydrogen bonding and Jahn-Teller distortion in groutite, α-MnOOH, and manganite, γ-MnOOH, and their relations to the manganese dioxides ramsdellite and pyrolusite. Journal of Solid State Chemistry: 133: 486-500.

Internet Links for Pyrolusite

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    Localities for Pyrolusite

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