Cobaltomenite
A valid IMA mineral species - grandfathered
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About Cobaltomenite
Formula:
CoSeO3 · 2H2O
Colour:
dark red, pink-red, brownish pink, yellowish brown
Lustre:
Vitreous
Hardness:
2 - 2½
Specific Gravity:
3.42
Crystal System:
Monoclinic
Name:
Named for being the cobalt analogue of chalcomenite.
Type Locality:
Isostructural with:
Unique Identifiers
Mindat ID:
1092
Long-form identifier:
mindat:1:1:1092:0
IMA Classification of Cobaltomenite
Approved, 'Grandfathered' (first described prior to 1959)
IMA status notes:
Renamed by the IMA
IMA Formula:
Co2+Se4+O3·2H2O
First published:
1882
Approval history:
Renamed IMA 2007 s.p.
Classification of Cobaltomenite
4.JH.10
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
H : Selenites without additional anions, with H2O
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
H : Selenites without additional anions, with H2O
Dana 7th ed.:
34.2.3.2
34.2.3.2
34 : SELENITES, TELLURITES AND SULFITES
2 : A(XO3)·xH2O
34 : SELENITES, TELLURITES AND SULFITES
2 : A(XO3)·xH2O
28.1.12
28 : Selenites, Selenates, Tellurites, and Tellurates
1 : Selenites
28 : Selenites, Selenates, Tellurites, and Tellurates
1 : Selenites
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Cbm | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Cobaltomenite
Vitreous
Transparency:
Transparent, Translucent
Colour:
Dark red, pink-red, brownish pink, yellowish brown
Comment:
pale brown to yellowish brown with increasing nickel content.
Streak:
Dark pink
Hardness:
2 - 2½ on Mohs scale
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
3.42 g/cm3 (Measured) 3.422 g/cm3 (Calculated)
Comment:
Calculated using synthetic material
Optical Data of Cobaltomenite
Type:
Biaxial (-)
RI values:
nα = 1.681 nβ = 1.728 nγ = 1.769
2V:
Measured: 83° , Calculated: 82°
Max. Birefringence:
δ = 0.088
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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
Calculated, r
Pleochroism:
Visible
Comments:
X = pale pink; Y = pink; Z = red.
Comments:
Z ∧ c = 13 deg.
Chemistry of Cobaltomenite
Mindat Formula:
CoSeO3 · 2H2O
Element Weights:
Elements listed:
Crystallography of Cobaltomenite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 7.64 Å, b = 8.82 Å, c = 6.51 Å
β = 98.6°
β = 98.6°
Ratio:
a:b:c = 0.866 : 1 : 0.738
Unit Cell V:
433.74 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals minute. Forms include {001}, {100}, {010}, and {101}.
Comment:
Space Group: P21/n (synthetic).
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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CIF File Best | x | y | z | a | b | c
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Labels
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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) |
|---|---|---|---|---|---|---|---|
| 0014845 | Cobaltomenite | Wildner M (1990) Crystal structure refinements of synthetic cobaltomenite (CoSeO3*2H2O) and ahlfeldite (NiSeO3*2H2O) Neues Jahrbuch fur Mineralogie, Monatshefte 1990 353-362 | 1990 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.70 Å | (100) |
| 3.46 Å | (70) |
| 3.017 Å | (55) |
| 3.80 Å | (50) |
| 2.738 Å | (45) |
| 2.378 Å | (40) |
| 1.734 Å | (35) |
Comments:
For synthetic material
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Cobaltomenite
Place of Conservation of Type Material:
No designated type specimen.
Associated Minerals at Type Locality:
Other Language Names for Cobaltomenite
Relationship of Cobaltomenite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 5 photos of Cobaltomenite associated with Trogtalite | CoSe2 |
| 4 photos of Cobaltomenite associated with Chalcomenite | CuSeO3 · 2H2O |
| 4 photos of Cobaltomenite associated with 'Sandstone' | |
| 3 photos of Cobaltomenite associated with Ferroselite | FeSe2 |
| 2 photos of Cobaltomenite associated with Karpenkoite | Co3(V2O7)(OH)2 · 2H2O |
| 2 photos of Cobaltomenite associated with 'Asphaltite' | |
| 2 photos of Cobaltomenite associated with Nestolaite | CaSeO3 · H2O |
| 1 photo of Cobaltomenite associated with Klockmannite | CuSe |
| 1 photo of Cobaltomenite associated with Clausthalite | PbSe |
| 1 photo of Cobaltomenite associated with Demesmaekerite | Pb2Cu5(UO2)2(SeO3)6(OH)6 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 4.JH. | Magselite | [Mg(H2O)6](Se4+O3) |
| 4.JH. | Bernardevansite | Al2(SeO3)3 · 6H2O |
| 4.JH.05 | Chalcomenite | CuSeO3 · 2H2O |
| 4.JH.10 | Clinochalcomenite | CuSeO3(H2O)2 |
| 4.JH.10 | Ahlfeldite | Ni(SeO3) · 2H2O |
| 4.JH.15 | Mandarinoite | Fe3+2(Se4+O3)3 · (6-x)H2O (x = 0.0-1.0) |
| 4.JH.20 | Orlandiite | Pb3(SeO3)(Cl,OH)4 · H2O |
| 4.JH.30 | Nestolaite | CaSeO3 · H2O |
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 Cobaltomenite
mindat.org URL:
https://www.mindat.org/min-1092.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Cobaltomenite
Reference List:
Bertrand, Emile (1882) Sur la molybdoménite (sélénite de plomb), la cobaltoménite (sélénite de cobalt) et l'acide sélénieux de Cacheuta (La Plata) Bulletin de Minéralogie, 5 (4) 90-92 doi:10.3406/bulmi.1882.1713
Gattow, G.; Lieder, O. J. (1963) Über Ahlfeldit und Cobaltomenit. Die Naturwissenschaften, 50 (6). 222-223 doi:10.1007/bf00639275
Frost, Ray L., Keeffe, Eloise C. (2008) Raman spectroscopic study of the selenite minerals - chalcomenite CuSeO3·2H2O, clinochalcomenite and cobaltomenite. Journal of Raman Spectroscopy, 39 (12). 1789-1793 doi:10.1002/jrs.2036
Frost, Ray L., Reddy, B. Jagannadha, Keeffe, Eloise C. (2008) An Application of near Infrared Spectroscopy to the Study of the Selenite Minerals: Chalcomenite, Clinochalcomenite and Cobaltomenite. Journal of Near Infrared Spectroscopy, 16 (4) 399-407 doi:10.1255/jnirs.808
Charykova, M. V., Krivovichev, V. G., Yakovenko, O. S., Semenova, V. V., Semenov, K. N., Depmeier, W. (2012) Thermodynamics of arsenates, selenites, and sulfates in the oxidation zone of sulfide ores: VI. Solubility of synthetic analogs of ahlfeldite and cobaltomenite at 25°C. Geology of Ore Deposits, 54 (8) 638-646 doi:10.1134/s1075701512080041
Charykova, M. V., Krivovichev, V. G., Lelet, M. I., Yakovenko, O. S., Suleimanov, E. V., Depmeier, W., Semenova, V. V., Zorina, M. L. (2014) A calorimetric and thermodynamic investigation of the synthetic analogs of cobaltomenite, CoSeO3·2H2O, and ahlfeldite, NiSeO3·2H2O. American Mineralogist, 99 (4) 742-748 doi:10.2138/am.2014.4588
Localities for Cobaltomenite
Showing 17 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.
Argentina | |
| Grundmann et al. (2018) |
| Palache et al. (1951) +1 other reference |
| Ahlfeld Friedrich and Angelelll ... +2 other references | |
Bolivia | |
| Schnorrer-Köhler et al. (1990) +2 other references |
| Livingstone et al. (1984) |
| Smith et al. (2001) |
DR Congo | |
| Deliens (1996) +2 other references |
USA | |
| Patrick Haynes |
| Collected by and in the collection of ... | |
| |
| Kampf et al. (2025) | |
| Thorne (n.d.) +2 other references |
| King et al. (1995) |
| Rick Dalrymple Collection | |
| Chuck Adan specimen. Visual ... | |
| King (n.d.) |
| Bullock (1981) |
Quick NavTopAbout CobaltomeniteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
El Dragón mine, Porco Municipality, Antonio Quijarro Province, Potosí, Bolivia