Metahohmannite
A valid IMA mineral species - grandfathered
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About Metahohmannite
Formula:
Fe3+2(SO4)2O · 4H2O
Colour:
Orange
Specific Gravity:
2.568 (Calculated)
Crystal System:
Triclinic
Name:
The name is derived from 'meta', for its lower hydration level, and its relationship to hohmannite.
Unique Identifiers
Mindat ID:
2675
Long-form identifier:
mindat:1:1:2675:4
IMA Classification of Metahohmannite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Fe3+2O(S6+O4)2·4H2O
Classification of Metahohmannite
7.DB.30
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
B : With only medium-sized cations; insular octahedra and finite units
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
B : With only medium-sized cations; insular octahedra and finite units
31.9.5.1
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
9 : (AB)(XO4)Zq·xH2O
25.10.13
25 : Sulphates
10 : Sulphates of Fe alone
25 : Sulphates
10 : Sulphates of Fe alone
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 |
|---|---|---|
| Mhoh | 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 Metahohmannite
Transparency:
Translucent
Colour:
Orange
Density:
2.568 g/cm3 (Calculated)
Optical Data of Metahohmannite
Type:
Biaxial (+)
RI values:
nα = 1.709 nβ = 1.718 nγ = 1.734
2V:
Measured: 70° , Calculated: 76°
Max. Birefringence:
δ = 0.025
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:
r > v weak
Pleochroism:
Visible
Comments:
X = light yellow; Y = reddish yellow; Z = reddish brown.
Chemistry of Metahohmannite
Mindat Formula:
Fe3+2(SO4)2O · 4H2O
Element Weights:
Elements listed:
Crystallography of Metahohmannite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 7.3484(5) Å, b = 9.7710(6) Å, c = 7.1521(5) Å
α = 91.684(5)°, β = 98.523(5)°, γ = 86.390(5)°
α = 91.684(5)°, β = 98.523(5)°, γ = 86.390(5)°
Ratio:
a:b:c = 0.752 : 1 : 0.732
Unit Cell V:
506.75 ų (Calculated from Unit Cell)
Morphology:
Pulverulent masses.
Comment:
Non-standard setting.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
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) |
|---|---|---|---|---|---|---|---|
| 0003421 | Metahohmannite | Scordari F, Ventruti G, Gualtieri A F (2004) The structure of metahohmannite, Fe2[O(SO4)2].4H2O, by in situ synchrotron powder diffraction American Mineralogist 89 365-370 |  | 2004 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.18 Å | (100) |
| 4.27 Å | (71) |
| 3.28 Å | (71) |
| 2.96 Å | (71) |
| 2.70 Å | (71) |
| 2.49 Å | (71) |
| 9.7 Å | (57) |
Comments:
ICDD 39-379. Dehydrated from hohmannite.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47b : [Sulfates and sulfites] |
Type Occurrence of Metahohmannite
General Appearance of Type Material:
Orange powdery material in association with hohmannite.
Place of Conservation of Type Material:
No designated type specimen.
Geological Setting of Type Material:
Dehydration of hohmannite in a desert sulfate deposit.
Associated Minerals at Type Locality:
Other Language Names for Metahohmannite
Common Associates
Associations Based on Photo Data:
| 7 photos of Metahohmannite associated with Natrojarosite | NaFe3(SO4)2(OH)6 |
| 7 photos of Metahohmannite associated with Botryogen | MgFe3+(SO4)2(OH) · 7H2O |
| 7 photos of Metahohmannite associated with Chalcanthite | CuSO4 · 5H2O |
| 7 photos of Metahohmannite associated with Epsomite | MgSO4 · 7H2O |
| 3 photos of Metahohmannite associated with Copiapite | Fe2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 2 photos of Metahohmannite associated with Amarantite | Fe3+2(SO4)2O · 7H2O |
| 2 photos of Metahohmannite associated with Fibroferrite | Fe3+(SO4)(OH) · 5H2O |
| 1 photo of Metahohmannite associated with Hohmannite | Fe3+2(SO4)2O · 8H2O |
Related Minerals - Strunz-mindat Grouping
| 7.DB.05 | Svyazhinite | (Mg,Mn2+,Ca)(Al,Fe3+)(SO4)2F · 14H2O |
| 7.DB.05 | Aubertite | CuAl(SO4)2Cl · 14H2O |
| 7.DB.05 | Magnesioaubertite | (Mg,Cu)Al(SO4)2Cl · 14H2O |
| 7.DB.10 | Rostite | Al(SO4)(OH) · 5H2O |
| 7.DB.10 | Khademite | Al(SO4)F · 5H2O |
| 7.DB.15 | Jurbanite | Al(SO4)(OH) · 5H2O |
| 7.DB.20 | Minasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.20 | Anorthominasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.20 | Orthominasragrite | (V4+O)(SO4) · 5H2O |
| 7.DB.25 | Bobjonesite | (V4+O)(SO4) · 3H2O |
| 7.DB.27 | Karpovite | Tl2VO(SO4)2(H2O) |
| 7.DB.30 | Hohmannite | Fe3+2(SO4)2O · 8H2O |
| 7.DB.30 | Amarantite | Fe3+2(SO4)2O · 7H2O |
| 7.DB.35 | Calciocopiapite | CaFe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Zincocopiapite | ZnFe3+4(SO4)6(OH)2 · 18H2O |
| 7.DB.35 | Aluminocopiapite | Al2/3Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Copiapite | Fe2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Cuprocopiapite | Cu2+Fe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Magnesiocopiapite | MgFe3+4(SO4)6(OH)2 · 20H2O |
| 7.DB.35 | Ferricopiapite | Fe3+0.67Fe3+4(SO4)6(OH)2 · 20H2O |
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 Metahohmannite
mindat.org URL:
https://www.mindat.org/min-2675.html
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Please feel free to link to this page.
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References for Metahohmannite
Reference List:
Ungemach, Henri (1935) Sur certains minéraux sulfatés du Chili. Bulletin de Minéralogie, 58 (3) 97-221 doi:10.3406/bulmi.1935.4369
Bandy, Mark C. (1938) Mineralogy of three sulphate deposits of northern Chile. American Mineralogist, 23 (11) 669-760
Cesbron, Fabien (1964) Contribution à la Minéralogie des sulfates de fer hydratés. Bulletin de Minéralogie, 87 (2) 125-143 doi:10.3406/bulmi.1964.5721
Scordari, Fernando, Ventruti, Gennaro, Gualtieri, Alessandro F. (2004) The structure of metahohmannite, Fe3+2[O(SO4)2]·4H2O, by in situ synchrotron powder diffraction. American Mineralogist, 89 (2) 365-370 doi:10.2138/am-2004-2-316
Localities for Metahohmannite
Showing 9 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.
Australia | |
| Noble R.J et al. (1983) |
Chile | |
| Palache et al. (1951) +1 other reference |
| Bandy (1938) +1 other reference |
| Palache et al. (1951) |
| Peter G. Seroka collection |
Greece | |
| Rieck et al. (2018) |
| Rieck et al. (2018) |
USA | |
| Chemical Geology Volume 215 |
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Chile