Grischunite
A valid IMA mineral species
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About Grischunite
Formula:
NaCa2Mn2+5Fe3+(AsO4)6 · 2H2O
Colour:
Dark red-brown.
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.8
Crystal System:
Orthorhombic
Member of:
Name:
For the Grischun (Grisons; Graubünden) region in which the type locality is situated.
Unique Identifiers
Mindat ID:
1753
Long-form identifier:
mindat:1:1:1753:0
IMA Classification of Grischunite
Approved
IMA Formula:
NaCa2Mn2+5Fe3+(As5+O4)6·2H2O
Approval year:
1981
First published:
1984
Classification of Grischunite
8.CF.05
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
F : With large and medium-sized cations, RO4:H2O > 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
F : With large and medium-sized cations, RO4:H2O > 1:1
40.2.11.1
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2 : AB2(XO4)2·xH2O
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2 : AB2(XO4)2·xH2O
20.8.22
20 : Arsenates (also arsenates with phosphate, but without other anions)
8 : Arsenates of Mn
20 : Arsenates (also arsenates with phosphate, but without other anions)
8 : Arsenates 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.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Gcn | 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 Grischunite
Vitreous
Transparency:
Translucent
Colour:
Dark red-brown.
Streak:
Yellow red to yellow brown
Hardness:
5 on Mohs scale
Hardness:
VHN50=450 - 550 kg/mm2 - Vickers
Cleavage:
Perfect
Perfect along (010)
Perfect along (010)
Density:
3.8(2) g/cm3 (Measured) 4.144 g/cm3 (Calculated)
Optical Data of Grischunite
Type:
Biaxial (+)
RI values:
nα = 1.784(3) nβ = 1.785(3) nγ = 1.790(3)
2V:
Measured: 40° to 50°, Calculated: 50°
Max. Birefringence:
δ = 0.006
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:
extreme, r << v
Pleochroism:
Visible
Comments:
X = yellow green (X||b), Y = yellow brown (Y||a), and Z = dark red brown (Z||c)
Comments:
absorption Z ≃ Y » X
Chemistry of Grischunite
Mindat Formula:
NaCa2Mn2+5Fe3+(AsO4)6 · 2H2O
Element Weights:
Crystallography of Grischunite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 12.855(2) Å, b = 13.487(2) Å, c = 12.047(1) Å
Ratio:
a:b:c = 0.953 : 1 : 0.893
Unit Cell V:
2,088.65 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Lathlike crystals, elongated along b.
Comment:
Space Group: P cab.
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) |
|---|---|---|---|---|---|---|---|
| 0001131 | Grischunite | Bianchi R, Pilati T, Mannucci G (1987) Crystal structure of grischunite American Mineralogist 72 1225-1229 |  | 1987 | the old manganese mine, Falotta, Graubunden, Switzerland | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.839 Å | (100) |
| 3.150 Å | (90) |
| 3.015 Å | (80) |
| 3.617 Å | (70) |
| 2.943 Å | (60) |
| 6.037 Å | (30) |
| 4.244 Å | (30) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 7: Great Oxidation Event | <2.4 |
| 46 : Near-surface hydrothermal alteration of minerals (see also #22) |
Type Occurrence of Grischunite
General Appearance of Type Material:
Anhedral grains and lathlike crystals
Place of Conservation of Type Material:
Natural History Museum, Basel, Switzerland, MB19.295
Geological Setting of Type Material:
Alpine metamorphism of manganese ores, with abundant arsenic in surrounding rock.
Associated Minerals at Type Locality:
Synonyms of Grischunite
Other Language Names for Grischunite
Relationship of Grischunite to other Species
Member of:
Other Members of Wicksite Group:
| Bederite | Ca2(Mn2+)4(Fe3+)2(PO4)6 · 2H2O | Orth. mmm(2/m2/m2/m) |
| Liraite | NaCa2Mn2+2[Fe3+Fe2+]Mn2+2(PO4)6(H2O)2 | Orth. mm2 |
| Maneckiite | (Na◻)Ca2Fe2+2(Fe3+Mg)Mn2(PO4)6 · 2H2O | Orth. mmm(2/m2/m2/m) : Pbca |
| Tassieite | (Na,◻)Ca2(Mg,Fe2+,Fe3+)2(Fe2+,Mg)2(Fe3+,Mg)2(PO4)6 · 2H2O | Orth. mmm(2/m2/m2/m) : Pbca |
| Wicksite | NaCa2(Fe2+,Mn2+)4MgFe3+(PO4)6 · 2H2O | Orth. mmm(2/m2/m2/m) : Pbca |
Common Associates
Associations Based on Photo Data:
| 1 photo of Grischunite associated with Conichalcite | CaCu(AsO4)(OH) |
Related Minerals - Strunz-mindat Grouping
| 8.CF. | Ferraioloite | MgMn2+4(Fe2+0.5Al3+0.5)4Zn4(PO4)8(OH)4(H2O)20 |
| 8.CF. | Naalasite | NaAl(AsO3OH)2 · H2O |
| 8.CF. | Nafeasite | Na3Fe3+3(AsO3OH)6 · 3H2O |
| 8.CF. | Falsterite | Ca2MgMn2+2Fe2+2Fe3+2Zn4(PO4)8(OH)4(H2O)14 |
| 8.CF. | Espadaite | Na4Ca3Mg2[AsO3(OH)]2[AsO2(OH)2]10 · 7H2O |
| 8.CF. | Liraite | NaCa2Mn2+2[Fe3+Fe2+]Mn2+2(PO4)6(H2O)2 |
| 8.CF.05 | Tassieite | (Na,◻)Ca2(Mg,Fe2+,Fe3+)2(Fe2+,Mg)2(Fe3+,Mg)2(PO4)6 · 2H2O |
| 8.CF.05 | Bederite | Ca2(Mn2+)4(Fe3+)2(PO4)6 · 2H2O |
| 8.CF.05 | Wicksite | NaCa2(Fe2+,Mn2+)4MgFe3+(PO4)6 · 2H2O |
| 8.CF.05 | Maneckiite | (Na◻)Ca2Fe2+2(Fe3+Mg)Mn2(PO4)6 · 2H2O |
| 8.CF.10 | Haigerachite | KFe3+3(PO3OH)2[PO2(OH)2]6 · 4H2O |
| 8.CF.10 | Yazganite | NaFe3+2(Mg,Mn2+)(AsO4)3 · H2O |
| 8.CF.15 | Currierite | Na4Ca3MgAl4(AsO3OH)12 · 9H2O |
| 8.CF.20 | Ríosecoite | Ca2Mg(AsO3OH)3(H2O)2 |
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 Grischunite
mindat.org URL:
https://www.mindat.org/min-1753.html
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Please feel free to link to this page.
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References for Grischunite
Localities for Grischunite
Showing 1 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.
Switzerland (TL) | |
| Graeser et al. (1984) +1 other reference |
Quick NavTopAbout GrischuniteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Falotta, Tinizong, Surses, Albula Region, Grisons, Switzerland