Argandite
A valid IMA mineral species
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About Argandite
Emile Argand
Formula:
Mn7(VO4)2(OH)8
Colour:
Orange
Lustre:
Vitreous
Hardness:
3½ - 4
Specific Gravity:
3.71
Crystal System:
Monoclinic
Member of:
Name:
Named in honour of Emile Argand (1879-1940), Swiss geologist and mineralogist, who studied the tectonics of the Alps and of Asia. Argand was an early supporter of Wegener's theory of continental drift.
Isostructural with:
Unique Identifiers
Mindat ID:
40277
Long-form identifier:
mindat:1:1:40277:2
IMA Classification of Argandite
Classification of Argandite
8.BE.30
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
E : With only medium-sized cations, (OH, etc.):RO4 > 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
E : With only medium-sized cations, (OH, etc.):RO4 > 2:1
41.2.1.4
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
2 : (AB)7(XO4)2Zq
41 : ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
2 : (AB)7(XO4)2Zq
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 |
|---|---|---|
| Agd | 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 Argandite
Vitreous
Transparency:
Transparent
Colour:
Orange
Streak:
Pale orange
Hardness:
3½ - 4 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Probably parallel to {001}.
Probably parallel to {001}.
Density:
3.71(5) g/cm3 (Measured) 3.67(1) g/cm3 (Calculated)
Optical Data of Argandite
Type:
Biaxial (-)
RI values:
nα = 1.74 nβ = 1.762(4) nγ = 1.77
2V:
Calculated: 62°
Max. Birefringence:
δ = 0.030
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.
Pleochroism:
Visible
Comments:
Orange-yellow to orange.
Chemistry of Argandite
Mindat Formula:
Mn7(VO4)2(OH)8
Element Weights:
Elements listed:
Crystallography of Argandite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/m
Setting:
P21/m
Cell Parameters:
a = 5.498(2) Å, b = 12.265(3) Å, c = 10.092(2) Å
β = 95.594(3)°
β = 95.594(3)°
Ratio:
a:b:c = 0.448 : 1 : 0.823
Unit Cell V:
677.29 ų (Calculated from Unit Cell)
Morphology:
Anhedral grains.
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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Rotation
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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) |
|---|---|---|---|---|---|---|---|
| 0018517 | Argandite | Brugger J, Elliott P, Meisser N, Ansermet S (2011) Argandite, Mn7(VO4)2(OH)8, the V analogue of allactite from the metamorphosed Mn ores at Pipji, Turtmann Valley, Switzerland American Mineralogist 96 1894-1900 | 2011 | Pipji, Turtmann Valley, Switzerland | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.708 Å | (50) |
| 3.395 Å | (60) |
| 3.074 Å | (100) |
| 2.945 Å | (50) |
| 2.687 Å | (70) |
| 2.522 Å | (50) |
| 2.324 Å | (40) |
| 1.791 Å | (40) |
Comments:
Pipjitälli, Valais, Switzerland. The data are from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits |
Type Occurrence of Argandite
General Appearance of Type Material:
Argandite occurs as a rock-forming mineral in a manganosite-rich specimen. It forms orange anhedral grains up to 60 micron in diameter.
Place of Conservation of Type Material:
Geological Museum, Lausanne, Switzerland, reg. no. MGL90369.
Geological Setting of Type Material:
Metamorphosed synsedimentary exhalative Mn deposit.
Associated Minerals at Type Locality:
Synonyms of Argandite
Other Language Names for Argandite
Relationship of Argandite to other Species
Member of:
Other Members of Allactite Group:
Related Minerals - Strunz-mindat Grouping
| 8.BE.05 | Augelite | Al2(PO4)(OH)3 |
| 8.BE.10 | Grattarolaite | Fe3+3(PO4)O3 |
| 8.BE.15 | Cornetite | Cu3(PO4)(OH)3 |
| 8.BE.20 | Clinoclase | Cu3(AsO4)(OH)3 |
| 8.BE.25 | Gilmarite | Cu3(AsO4)(OH)3 |
| 8.BE.25 | Arhbarite | Cu2Mg(AsO4)(OH)3 |
| 8.BE.30 | Flinkite | Mn2+2Mn3+(AsO4)(OH)4 |
| 8.BE.30 | Raadeite | Mg7(PO4)2(OH)8 |
| 8.BE.30 | Allactite | Mn2+7(AsO4)2(OH)8 |
| 8.BE.35 | 'Mineral E (of Dunn, et. al., 1982)' | |
| 8.BE.35 | Chlorophoenicite | (Mn,Mg)3Zn2(AsO4)(OH,O)6 |
| 8.BE.35 | Magnesiochlorophoenicite | (Mg,Mn)3Zn2(AsO4)(OH,O)6 |
| 8.BE.40 | Gerdtremmelite | (Zn,Fe)(Al,Fe)2(AsO4)(OH)5 |
| 8.BE.45 | Dixenite | CuMn2+14Fe2+(SiO4)2(As5+O4)(As3+O3)5(OH)6 |
| 8.BE.45 | Mcgovernite | Mn19Zn3(AsO4)3(AsO3)(SiO4)3(OH)21 |
| 8.BE.45 | Hematolite | (Mn,Mg,Al,Fe3+)15(As5+O4)2(As3+O3)(OH)23 |
| 8.BE.45 | Turtmannite | (Mn,Mg)22.5Mg3-3x((V5+,As5+)O4)3(As3+O3)x(SiO4)3O5-5x(OH)20+x |
| 8.BE.45 | Carlfrancisite | Mn2+3(Mn2+,Mg,Fe3+,Al)42[As3+O3]2(As5+O4)4[(Si,As5+)O4]6[(As5+,Si)O4]2(OH)42 |
| 8.BE.45 | Arakiite | (Zn,Mn2+)(Mn2+,Mg)12(Fe3+,Al)2(As5+O4)2(As3+O3)(OH)23 |
| 8.BE.45 | Kraisslite | Zn3(Mn,Mg)25(Fe3+,Al)(As3+O3)2[(Si,As5+)O4]10(OH)16 |
| 8.BE.50 | Synadelphite | Mn2+9(As5+O4)2(As3+O3)(OH)9 · 2H2O |
| 8.BE.55 | Holdenite | (Mn2+,Mg)6Zn3(AsO4)2(SiO4)(OH)8 |
| 8.BE.60 | Kolicite | Mn2+7Zn4(AsO4)2(SiO4)2(OH)8 |
| 8.BE.65 | Sabelliite | (Cu,Zn)2Zn(AsO4,SbO4)(OH)3 |
| 8.BE.70 | Jarosewichite | Mn2+3Mn3+(AsO4)(OH)6 |
| 8.BE.75 | Theisite | Cu5Zn5(AsO4,SbO4)2(OH)14 |
| 8.BE.80 | Coparsite | Cu4(AsO4,VO4)O2Cl |
| 8.BE.85 | Waterhouseite | Mn2+7(PO4)2(OH)8 |
| 8.BE.90 | Vasilseverginite | Cu9O4(AsO4)2(SO4)2 |
Fluorescence of Argandite
Not fluorescent.
Other Information
Notes:
Slowly soluble in cold 10% HCl.
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 Argandite
mindat.org URL:
https://www.mindat.org/min-40277.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Argandite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2010) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) CNMNC Newsletter No 4. Mineralogical Magazine, 74 (4) 797-800 doi:10.1180/s0026461x00038925
Localities for Argandite
Showing 3 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.
Italy | |
| SCXRD: L. Bindi - University of Firenze ... +1 other reference |
Switzerland (TL) | |
| Williams et al. (2010) +1 other reference |
| Ansermet (2012) |
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Pipjitälli, Turtmann Valley, Turtmann-Unterems, Leuk, Valais, Switzerland