Pyrochroite
A valid IMA mineral species - grandfathered
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About Pyrochroite
Formula:
Mn(OH)2
Colour:
Colourless, greenish, bluish (fresh), brown to black (exposed); flesh-red or amethystine in transmitted light
Lustre:
Pearly
Hardness:
2½ - 3
Specific Gravity:
3.23 - 3.27
Crystal System:
Trigonal
Member of:
Name:
Named in 1864 by Lars Johan Igelstrom from the Greek πύρ, "fire", and χρώσις, "colouring", in allusion to the change of color upon ignition.
Occurs as either a hydration product of manganosite (MnO) or as a primary mineral in some volcanogenic massive sulfide (VMS) deposits.
Unique Identifiers
Mindat ID:
3317
Long-form identifier:
mindat:1:1:3317:2
Similar Names
| Pyrochrotite | A synonym of Pyrostilpnite |
IMA Classification of Pyrochroite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mn2+(OH)2
Type description reference:
Classification of Pyrochroite
4.FE.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
E : Hydroxides with OH, without H2O; sheets of edge-sharing octahedra
6.2.1.3
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
2 : X(OH)2
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
2 : X(OH)2
7.18.10
7 : Oxides and Hydroxides
18 : Oxides of Mn
7 : Oxides and Hydroxides
18 : Oxides of Mn
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Pyc | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Pyc | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
| Pyc | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Pyrochroite
Pearly
Transparency:
Translucent, Opaque
Comment:
Pearly on cleavages
Colour:
Colourless, greenish, bluish (fresh), brown to black (exposed); flesh-red or amethystine in transmitted light
Hardness:
2½ - 3 on Mohs scale
Tenacity:
Elastic
Cleavage:
Perfect
On {0001}
On {0001}
Density:
3.23 - 3.27 g/cm3 (Measured) 3.25 g/cm3 (Calculated)
Optical Data of Pyrochroite
Type:
Uniaxial (-)
RI values:
nω = 1.68 - 1.681 nε = 1.72 - 1.723
Max. Birefringence:
δ = 0.040 - 0.042
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Pleochroism:
Visible
Comments:
Dichroic: O = brown; E = lighter brown.
Comments:
Strongly reflecting in polished section (black altered material).
Chemistry of Pyrochroite
Mindat Formula:
Mn(OH)2
Elements listed:
Crystallography of Pyrochroite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
P3m1
Setting:
P3m1
Cell Parameters:
a = 3.33(1) Å, c = 4.70(2) Å
Ratio:
a:c = 1 : 1.411
Unit Cell V:
45.14 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Crystals tabular {0001}; also less commonly rhombohedral with large {1012} or {1011}. Rarely prismatic [0001] with {1120} and {0001} developed. Foliated masses.
Crystal Structure
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Unit Cell | Unit Cell Packed
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0008112 | Pyrochroite | Parise J B, Theroux B, Li R, Loveday J S, Marshall W G, Klotz S (1998) Pressure dependence of hydrogen bonding in metal deuteroxides: a neutron powder diffraction study of Mn(OD)2 and beta-Co(OD)2. Physics and Chemistry of Minerals 25 130-137 | 1998 | 0 | 293 | ||
| 0011790 | Pyrochroite | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Crystal Structures 1 239-444 | 1963 | 0 | 293 | ||
| 0008113 | Pyrochroite | Parise J B, Theroux B, Li R, Loveday J S, Marshall W G, Klotz S (1998) Pressure dependence of hydrogen bonding in metal deuteroxides: a neutron powder diffraction study of Mn(OD)2 and beta-Co(OD)2. Physics and Chemistry of Minerals 25 130-137 | 1998 | 0.7 | 293 | ||
| 0008114 | Pyrochroite | Parise J B, Theroux B, Li R, Loveday J S, Marshall W G, Klotz S (1998) Pressure dependence of hydrogen bonding in metal deuteroxides: a neutron powder diffraction study of Mn(OD)2 and beta-Co(OD)2. Physics and Chemistry of Minerals 25 130-137 | 1998 | 2.4 | 293 | ||
| 0008115 | Pyrochroite | Parise J B, Theroux B, Li R, Loveday J S, Marshall W G, Klotz S (1998) Pressure dependence of hydrogen bonding in metal deuteroxides: a neutron powder diffraction study of Mn(OD)2 and beta-Co(OD)2. Physics and Chemistry of Minerals 25 130-137 | 1998 | 4.6 | 293 | ||
| 0008116 | Pyrochroite | Parise J B, Theroux B, Li R, Loveday J S, Marshall W G, Klotz S (1998) Pressure dependence of hydrogen bonding in metal deuteroxides: a neutron powder diffraction study of Mn(OD)2 and beta-Co(OD)2. Physics and Chemistry of Minerals 25 130-137 | 1998 | 7.8 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.6 Å | (10) |
| 2.48 Å | (3) |
| 2.76 Å | (2) |
| 1.542 Å | (2) |
| 3.09 Å | (1) |
| 2.41 Å | (1) |
| 2.04 Å | (1) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] |
Type Occurrence of Pyrochroite
Synonyms of Pyrochroite
Other Language Names for Pyrochroite
Dutch:Pyrochroiet
German:Pyrochroit
Japanese:パイロクロアイト
Russian:Пирохроит
Simplified Chinese:羟锰矿
Spanish:Pirocroita
Relationship of Pyrochroite to other Species
Member of:
Other Members of Brucite Group:
| Amakinite | Fe2+(OH)2 | Trig. |
| Brucite | Mg(OH)2 | Trig. 3m(32/m) : P3m1 |
| Portlandite | Ca(OH)2 | Trig. 3m(32/m) : P3m1 |
| Theophrastite | Ni(OH)2 | Trig. 3m(32/m) : P3m1 |
Common Associates
Associations Based on Photo Data:
| 47 photos of Pyrochroite associated with Zincite | ZnO |
| 44 photos of Pyrochroite associated with Native Lead | Pb |
| 44 photos of Pyrochroite associated with Calcite | CaCO3 |
| 26 photos of Pyrochroite associated with Willemite | Zn2SiO4 |
| 23 photos of Pyrochroite associated with Mooreite | Mg9◻2Mn2Zn4(SO4)2(OH)26 · 8H2O |
| 23 photos of Pyrochroite associated with Hydrocerussite | Pb3(CO3)2(OH)2 |
| 23 photos of Pyrochroite associated with Sussexite | Mn2+BO2(OH) |
| 22 photos of Pyrochroite associated with Rhodochrosite | MnCO3 |
| 19 photos of Pyrochroite associated with Shigaite | Mn6Al3(OH)18[Na(H2O)6](SO4)2 · 6H2O |
| 17 photos of Pyrochroite associated with Allactite | Mn2+7(AsO4)2(OH)8 |
Related Minerals - Strunz-mindat Grouping
| 4.FE. | Nannoniite | Al2(OH)5F |
| 4.FE.05 | Brucite | Mg(OH)2 |
| 4.FE.05 | Theophrastite | Ni(OH)2 |
| 4.FE.05 | Amakinite | Fe2+(OH)2 |
| 4.FE.05 | Portlandite | Ca(OH)2 |
| 4.FE.10 | Doyleite | Al(OH)3 |
| 4.FE.10 | Bayerite | Al(OH)3 |
| 4.FE.10 | Nordstrandite | Al(OH)3 |
| 4.FE.10 | Gibbsite | Al(OH)3 |
| 4.FE.15 | Lepidocrocite | Fe3+O(OH) |
| 4.FE.15 | Böhmite | AlO(OH) |
| 4.FE.20 | Heterogenite | Co3+O(OH) |
| 4.FE.20 | Grimaldiite | CrO(OH) |
| 4.FE.25 | Lithiophorite | (Al,Li)MnO2(OH)2 |
| 4.FE.25 | Feitknechtite | Mn3+O(OH) |
| 4.FE.30 | Quenselite | PbMnO2(OH) |
| 4.FE.35 | Ferrihydrite | Fe3+10O14(OH)2 |
| 4.FE.40 | Vernadite | (Mn4+,Fe3+,Ca,Na)(O,OH)2 · nH2O |
| 4.FE.40 | Feroxyhyte | Fe3+O(OH) |
| 4.FE.45 | Quetzalcoatlite | Zn6Cu3(TeO6)2(OH)6 · AgxPbyClx+2y |
| 4.FE.50 | Fuettererite | Pb3Cu2+6Te6+O6(OH)7Cl5 |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Pyrochroite
mindat.org URL:
https://www.mindat.org/min-3317.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Pyrochroite
Reference List:
Schulten, A. de (1887) Reproduction artificielle de la pyrochroïte (hydrate manganeux cristallisé) Bulletin de Minéralogie, 10 (9) 326-328 doi:10.3406/bulmi.1887.2084
Sjögren, Hj. (1905) Om kristalliserad Pyrochroit från Långbans grufvor. Geologiska Föreningen i Stockholm Förhandlingar, 27 (1) 37-41 doi:10.1080/11035890509448020
Palache, Charles (1935) The minerals of Franklin and Sterling Hill, Sussex County, New Jersey. Professional Paper 180. US Geological Survey 135 pp. doi:10.3133/pp180
Kato, Akira, Yui, Shunzo (1960) Pyrochroite from Hamayokokawa mine, Nagano Prefecture. Journal of the Mineralogical Society of Japan, 4 (6) 453-455 doi:10.2465/gkk1952.4.453
WATANABE, TAKEO, KATO, AKIRA, ITO, JUN (1960) The minerals of the Noda-Tamagawa mine, Iwaté Prefecture, Japan: II. Pyrochroite ore (Kimiman-kô) and its origin. Mineralogical Journal, 3 (1). 30-41 doi:10.2465/minerj1953.3.30
Bricker, Owen P. (1965) Some stability relations in the system Mn-O2-H2O at 25° and one atmosphere total pressure. American Mineralogist, 50 (9) 1296-1354
Boström, Kurt (1981) On the origin of the native lead-pyrochroite association in Långban. Geologiska Föreningen i Stockholm Förhandlingar, 103 (1) 120-121 doi:10.1080/11035898109455217
Localities for Pyrochroite
Showing 79 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Atlantic Ocean | |
| Gablina et al. (2006) |
Burkina Faso | |
| Kříbek et al. (2016) |
Canada | |
| 179-181. +2 other references |
China | |
| Zhao et al. (2024) |
| Zhongtang Yang et al. (2008) +1 other reference |
| Yeh et al. (1999) |
| Xingfen Wang (1989) +1 other reference |
| Hongjun Qu (1992) |
| Hongjun Qu (1992) |
| Hongjun Qu (1992) | |
| Zhangxiang Peng (1990) |
Egypt | |
| El-Habaak et al. (2016) |
| Fathy et al. (2025) |
| Manganese Reserves and Resources of the ... |
Germany | |
| Schnorrer et al. (2001) |
Ghana | |
| Mücke et al. (1999) |
India | |
| Rao et al. (1979) |
Italy | |
| Gianluca Armellino specimen - ... |
| Parola et al. (2023) |
| Fernando Caboni et al. (2024) |
| Fernando Caboni et al. (2024) | |
| Analyzed by Marco Ciriotti +1 other reference |
| Published on LIBVRNA N°1 may 2021. Analysed by Spectralab srl (SEM/EDS and Raman) |
Japan | |
| Mayumi Yoshinaga (1963) |
| Kato (2010) |
| Matsubara Satoshi et al. (1980) |
| - (n.d.) +2 other references |
| Mayumi Yoshinaga (1963) |
| |
| Fuzimoto (2006) |
| Akira Kato (2011) |
| Akira Kato (2011) | |
| Yoshinaga et al. (1963) |
| Akira Kato (undated manuscript) +2 other references |
| Mayumi Yoshinaga (1963) |
| Fumitoshi HIROWATARI (1961) |
| Mayumi Yoshinaga (1963) | |
Namibia | |
| Dunn (1991) |
Poland | |
| Ł. Kruszewski PXRD & pXRF data (paper in preparation) |
Romania | |
| minerals-of-the-carpathians.eu (2008) |
| Hîrtopanu (1997) +1 other reference |
Russia | |
| Kassandrov et al. (2009) |
| Kassandrov et al. (2009) | |
| Talovina et al. (2003) |
Saudi Arabia | |
| Gahlan et al. (2021) |
Slovakia | |
| Radvanec M. et al. (2022) |
| Radvanec M. and Gonda S. (2020) |
South Africa | |
| Mitchell et al. (2004) |
| Pohl et al. (1991) |
| Pohl et al. (1991) | |
| Pohl et al. (1991) | |
Spain | |
| Mendoza et al. (2006) |
Sweden | |
| Gatedal (n.d.) |
| |
| Gatedal (n.d.) |
| Holtstam et al. (1999) | |
| Flink (1922) | |
| Österberg (2003) | |
| Gatedal (n.d.) |
| Moore (1978) |
| Holtstam et al. (1998) | |
| Flink (1886) +2 other references | |
| Nysten (1984) |
| [Am Min 50 (1965) +1 other reference |
Switzerland | |
| Weibel et al. (1990) |
UK | |
| Bernie Millington Collection |
| R. E. Bevins (1988) |
USA | |
| Prenn et al. (1991) |
| Prenn et al. (1991) |
| Rogers (1919) +3 other references |
| Heinrich et al. (2004) |
| Castor et al. (2004) |
| Palache (1935) +1 other reference |
| King | |
| Palache (1935) | |
| Palache (1935) | |
| Palache (1935) +1 other reference |
| Peter Chin | |
Venezuela | |
| Domènech et al. (2020) |
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Wessels Mine, Joe Morolong Local Municipality, John Taolo Gaetsewe District Municipality, Northern Cape, South Africa