Groutite
A valid IMA mineral species - grandfathered
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About Groutite
Frank Fitch Grout
Formula:
Mn3+O(OH)
Colour:
Black, may be iridescent
Lustre:
Sub-Adamantine, Resinous, Waxy, Greasy, Dull
Hardness:
3½ - 4
Specific Gravity:
4.144
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1945 by John W. Gruner in honor of Frank Fitch Grout (August 1, January 24, 1880 Rockford, Illinois - August 1, 1958 Minneapolis, MN), petrologist, University of Minnesota, USA.
Co-Type Localities:
Polymorph of:
Isostructural with:
Diaspore Group.
Final product of laser-induced degradation of "groutellite" (a variety of ramsdellite), with hausmannite as a possible intermediate.
Final product of laser-induced degradation of "groutellite" (a variety of ramsdellite), with hausmannite as a possible intermediate.
Unique Identifiers
Mindat ID:
1756
Long-form identifier:
mindat:1:1:1756:1
GUID
(UUID V4):
(UUID V4):
62ada685-1b6f-4651-8369-a767bab2e044
IMA Classification of Groutite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1947
Classification of Groutite
4.FD.10
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
D : Hydroxides with OH, without H2O; chains of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
D : Hydroxides with OH, without H2O; chains of edge-sharing octahedra
6.1.1.3
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
1 : XO(OH)
7.18.8
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 |
|---|---|---|
| Gro | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Gro | 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 |
Pronunciation of Groutite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Groutite
Sub-Adamantine, Resinous, Waxy, Greasy, Dull
Transparency:
Opaque
Colour:
Black, may be iridescent
Streak:
dark brown
Hardness:
3½ - 4 on Mohs scale
Hardness:
VHN100=630 - 711 kg/mm2 - Vickers
Tenacity:
Brittle
Cleavage:
Perfect
Perfect on {010}
Less perfect {100}
Perfect on {010}
Less perfect {100}
Fracture:
Irregular/Uneven, Splintery
Density:
4.144 g/cm3 (Measured) 4.172 g/cm3 (Calculated)
Optical Data of Groutite
Type:
Biaxial (+)
RI values:
nα = 2.100 - 2.200 nγ = 2.100 - 2.200
2V:
Measured: 40° to 50°
Birefringence:
0.100
Max Birefringence:
δ = 0.000
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Moderate
Optical Extinction:
Parallel
Reflectivity:
| Wavelength | R1 | R2 |
|---|---|---|
| 400nm | 13.7 % | 22.0% |
| 420nm | 13.4 % | 21.3% |
| 440nm | 13.3 % | 20.7% |
| 460nm | 13.1% | 20.2% |
| 480nm | 13.0% | 19.7% |
| 500nm | 13.0% | 19.4% |
| 520nm | 12.9% | 19.1% |
| 540nm | 12.9% | 19.0% |
| 560nm | 12.8% | 19.0% |
| 580nm | 12.7% | 18.7% |
| 600nm | 12.7% | 18.6% |
| 620nm | 12.7% | 18.5% |
| 640nm | 12.6% | 18.3% |
| 660nm | 12.5% | 18.2% |
| 680nm | 12.4% | 18.0% |
| 700nm | 12.4% | 17.9% |
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 22.0%.
R1 shown in black, R2 shown in red
Pleochroism:
Strong
Comments:
X = very dark brown to black; Y = yellowish brown.
Comments:
Strong pleochroism distinguishes groutite from manganite.
Chemistry of Groutite
Mindat Formula:
Mn3+O(OH)
Elements listed:
Crystallography of Groutite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 4.560 Å, b = 10.700 Å, c = 2.870 Å
Ratio:
a:b:c = 0.426 : 1 : 0.268
Unit Cell V:
140.03 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Wedge- or lens-shaped crystals. Type material showed: {110}, {120}, {130}, {010}, {100}, {111}, {021}, {134}
Twinning:
Reported. [Compare twinning in isostructural diaspore.]
Comment:
Non-standard space-group setting Pbnm.
Crystal Structure
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Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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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) |
|---|---|---|---|---|---|---|---|
| 0011832 | Groutite | Wyckoff R W G (1963) Second edition. Interscience Publishers, New York, New York Crystal Structures 1 290-295 | 1963 | 0 | 293 | ||
| 0013941 | Groutite | Kohler T, Armbruster T, Libowitzky E (1997) Hydrogen bonding and Jahn-Teller distortion in groutite, alpha-MnOOH, and manganite, gamma-MnOOH, and their relations to the manganese dioxides ramsdellite and pyrolusite Journal of Solid State Chemistry 133 486-500 | 1997 | Nchwaning Mine, Kalahari manganese field, Republic of South Africa | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.349 Å | (9) |
| 4.195 Å | (100) |
| 3.471 Å | (10) |
| 2.8099 Å | (34) |
| 2.6743 Å | (29) |
| 2.5294 Å | (13) |
| 2.4288 Å | (4) |
| 2.3684 Å | (48) |
| 2.3076 Å | (17) |
| 2.2795 Å | (2) |
| 2.2297 Å | (2) |
| 2.2119 Å | (7) |
| 2.0078 Å | (5) |
| 1.9569 Å | (3) |
| 1.9372 Å | (4) |
| 1.7984 Å | (3) |
| 1.7833 Å | (2) |
| 1.7609 Å | (9) |
| 1.7354 Å | (6) |
| 1.6932 Å | (26) |
| 1.6055 Å | (18) |
| 1.5964 Å | (7) |
| 1.5604 Å | (3) |
| 1.5145 Å | (9) |
| 1.4848 Å | (1) |
| 1.4622 Å | (4) |
| 1.4491 Å | (4) |
| 1.4348 Å | (6) |
Comments:
ICDD 24-713 (Cayuna Range, Minnesota, USA) plus 51 lines of 1-4 intensity to 0.8227; see also ICDD 12-733 but with estimated intensities.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-𝑇 alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47h : [Near-surface oxidized, dehydrated minerals] |
Type Occurrence of Groutite
Co-Type Localities:
Place of Conservation of Type Material:
The Natural History Museum, London, England, number 1948,106.
National Museum of Natural History, Washington, D.C., USA, number 105004.
National Museum of Natural History, Washington, D.C., USA, number 105004.
Geological Setting of Type Material:
Late stage mineralization in vugs in Banded Iron Formation (BIF)
Associated Minerals at Type Locality:
Reference:
Gruner, John W (1947) Groutite, HMnO2, a new mineral of the diaspore-goethite group. American Mineralogist: 32: 654-659.
Other Language Names for Groutite
Relationship of Groutite to other Species
Member of:
Other Members of this group:
| Bracewellite | CrO(OH) | Orth. mmm (2/m 2/m 2/m) |
| Diaspore | AlO(OH) | Orth. mmm (2/m 2/m 2/m) |
| Goethite | α-Fe3+O(OH) | Orth. mmm (2/m 2/m 2/m) |
| Montroseite | (V3+,Fe3+)O(OH) | Orth. mmm (2/m 2/m 2/m) |
| Tsumgallite | GaO(OH) | Orth. mmm (2/m 2/m 2/m) |
Common Associates
Associated Minerals Based on Photo Data:
| 19 photos of Groutite associated with Petrified Wood | |
| 15 photos of Groutite associated with Calcite | CaCO3 |
| 11 photos of Groutite associated with Baryte | BaSO4 |
| 11 photos of Groutite associated with Rhodochrosite | MnCO3 |
| 5 photos of Groutite associated with Kutnohorite | CaMn2+(CO3)2 |
| 4 photos of Groutite associated with Ramsdellite | Mn4+O2 |
| 4 photos of Groutite associated with Vesuvianite | Ca19Fe3+Al4(Al6Mg2)(◻4)◻[Si2O7]4[(SiO4)10]O(OH)9 |
| 4 photos of Groutite associated with Hureaulite | Mn2+5(PO3OH)2(PO4)2 · 4H2O |
| 4 photos of Groutite associated with Manganite | Mn3+O(OH) |
| 3 photos of Groutite associated with Quartz | SiO2 |
Related Minerals - Strunz-mindat Grouping
| 4.FD.05 | Spertiniite | Cu(OH)2 |
| 4.FD.10 | Bracewellite | CrO(OH) |
| 4.FD.10 | Diaspore | AlO(OH) |
| 4.FD.10 | Guyanaite | CrO(OH) |
| 4.FD.10 | Montroseite | (V3+,Fe3+)O(OH) |
| 4.FD.10 | Tsumgallite | GaO(OH) |
| 4.FD.15 | Manganite | Mn3+O(OH) |
| 4.FD.20 | Yttrotungstite-(Y) | YW2O6(OH)3 |
| 4.FD.20 | Yttrotungstite-(Ce) | (Ce,Nd,Y)W2O6(OH)3 |
| 4.FD.25 | Frankhawthorneite | Cu2Te6+O4(OH)2 |
| 4.FD.30 | Khinite | Pb2+Cu2+3[Te6+O6](OH)2 |
| 4.FD.30 | Khinite-3T | Pb2+Cu2+3Te6+O6(OH)2 |
| 4.FD.30 | Housleyite | Pb6CuTe6+4O18(OH)2 |
Fluorescence of Groutite
Not fluorescent in ultraviolet
Other Information
Thermal Behaviour:
Groutite is infusible and loses water on heating in air at temperatures above 200°C. Heating at 150°C in air for five days does not affect it.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Manganese ore
Internet Links for Groutite
mindat.org URL:
https://www.mindat.org/min-1756.html
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Groutite
Reference List:
Gruner, John W. (1947) Groutite, HMnO2, a new mineral of the diaspore-goethite group. American Mineralogist, 32 (11-12) 654-659
Collin, R. L., Lipscomb, W. N. (1949) The crystal structure of groutite, HMnO2. Acta Crystallographica, 2 (2) 104-106 doi:10.1107/s0365110x49000230
Segeler, Curt G. (1959) Notes on a second occurrence of groutite. American Mineralogist, 44 (7-8) 877-878
Klingsberg, C., Roy, R. (1959) Stability and interconvertibility of phases in the system Mn-O-OH. American Mineralogist, 44 (7-8) 819-838
Fleischer, Michael, Richmond, W. E., Evans, Howard T. (1962) Studies of the manganese oxides. V. Ramsdellite, MnO2, an orthorhombic dimorph of pyrolusite. American Mineralogist, 47 (1-2) 47-58
Lima-De-Faria, J., Lopes-Vieira, A. (1964) The transformation of groutite (α-MnOOH) into pyrolusite (MnO2) Mineralogical Magazine and Journal of the Mineralogical Society, 33 (266) 1024-1031 doi:10.1180/minmag.1964.033.266.10
Dent Glasser, L. S., Smith, Ian B. (1965) Topotaxy in the system MnO-O-H2O: groutite–ramsdellite–pyrolusite. Mineralogical Magazine and Journal of the Mineralogical Society, 35 (270) 327-334 doi:10.1180/minmag.1965.035.270.06
Dent Glasser, L. S., Ingram, L. (1968) Refinement of the crystal structure of groutite – MnOOH. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 24 (9) 1233-1236 doi:10.1107/s0567740868004036
Majmundar, H. H. (1969) Ramsdellite and groutite from Nova Scotia. The Canadian Mineralogist, 9 (5) 718-720
Kohler, Thomas, Armbruster, Thomas, Libowitzky, Eugen (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 doi:10.1006/jssc.1997.7516
Localities for Groutite
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.
Andorra | |
| Valenti Turu and Michels (1992) |
Argentina | |
| Sureda (1978) |
Australia | |
| |
| Nickel et al. (1993) |
| Mineralogical Record 24 | |
| Nickel et al. (1993) | |
Austria | |
| Niedermayr et al. (1995) |
Belgium | |
| Hatert et al. (2014) |
Brazil | |
| Reynaldo Contreira collection |
Canada | |
| Majmundar (1969) |
| Boyle (1972) | |
| Richard Gunter specimen (ID by XRD) |
| 179-181. +2 other references |
China | |
| Zhicheng Lü et al. (2002) |
| Xingfen Wang (1989) |
France | |
| Wittern et al. (Cologne) |
| Perseil (1975) | |
| Perseil (1975) | |
| Perseil (1967) |
| De Ascenção Guedes et al. (2002) |
| Berbain et al. (2005) |
Gabon | |
| Lheur (2001) |
Germany | |
| Weiß (1990) |
| Walenta (1992) |
| Aufschluss 50 (1999) |
| |
| Vik Vanrusselt collection | |
| Neschen (n.d.) |
| Lapis 2003 (2) |
| Färber (n.d.) +1 other reference |
Greece | |
| |
| Andrew P. Fornadel et al. (2011) |
Hungary | |
| Szakáll & Jánosi (1996) |
| Koch: Minerals of Hungary |
India | |
| Rao +1 other reference |
Italy | |
| Castellaro (2008) |
Japan | |
| Dr. Matsuo Nambu collection (curated at Geological Survey of Japan) |
| Miura +5 other references |
Kazakhstan | |
| Evseev (1995) |
Mexico | |
| www.minrec.org (2005) |
| Megaw |
| Rocks & Min.: 56:247. |
Norway | |
| Neumann (1985) |
| Breivik et al. (2007) |
Portugal | |
| |
| Martins da Pedra collection |
Romania | |
| minerals-of-the-carpathians.eu (2008) |
| Hîrtopanu (1997) +1 other reference |
Russia | |
| [World of Stones 12:49] | |
| Econ Geol (1995) |
South Africa | |
| Cairncross et al. (1995) |
| Von Bezing et al. (1991) |
| Cairncross et al. (1995) | |
| King (n.d.) | |
Spain | |
| Dill et al. (2023) |
| Mining Museum in La Union collection |
| |
Sweden | |
| Sandström et al. (2009) |
| Sandström et al. (2009) | |
Ukraine | |
| Dominik Schlaefli - collection |
| Łukasz Kruszewski |
USA | |
| Christian Rewitzer collection |
| Galbraith et al. (1959) +1 other reference |
| Anthony et al. (1995) |
| Anthony et al. (1995) +1 other reference |
| Anthony et al. (1995) |
| Anthony et al. (1995) | |
| Anthony et al. (1995) |
| Cousins (1972) +1 other reference |
| Schooner (circa 1980s) |
| Schooner (circa 1985) |
| Heinrich et al. (2004) |
| Heinrich et al. (2004) |
| Heinrich et al. (2004) | |
| Gruner (1947) |
| Amer.Min. (1945) |
| R&M 48:6 p 420 | |
| 21:97 +2 other references | |
| Allen Lundgren collection | |
| Castor et al. (2004) |
| Klein et al. (1967) +2 other references |
| Northrop et al. (1996) |
| Segeler (1959) +1 other reference |
| American Mineralogist 44:877-878 +1 other reference | |
| Sangameshwar et al. (1983) |
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Holbrook, Navajo County, Arizona, USA