Vajdakite
A valid IMA mineral species
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About Vajdakite
Josef Vajdak
Formula:
[(Mo6+O2)2(H2O)2As3+2O5] · 3H2O
Colour:
Green to grey-green
Lustre:
Vitreous
Specific Gravity:
3.50
Crystal System:
Monoclinic
Name:
After Josef Vajdak (born March 31, 1930, in Helena, Montana, USA, deceased June 21, 2019, Massapequa, New York). American mineral collector and dealer of rare minerals.
An arsenite. The first molybdenyl-bearing mineral to date (compare the second one, bouškaite, and the third one, hasanovite).
Unique Identifiers
Mindat ID:
7053
Long-form identifier:
mindat:1:1:7053:5
IMA Classification of Vajdakite
Approved
IMA Formula:
(Mo6+O2)2As3+2O5·3H2O
Approval year:
1998
First published:
2002
Type description reference:
Classification of Vajdakite
4.JC.20
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
J : Arsenites, antimonites, bismuthites, sulfites, selenites, tellurites; iodates
C : Arsenites, antimonites, bismuthites; 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
C : Arsenites, antimonites, bismuthites; without additional anions, with H2O
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 |
|---|---|---|
| Vaj | 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 Vajdakite
Vitreous
Transparency:
Transparent
Colour:
Green to grey-green
Streak:
White to light gray green
Tenacity:
Brittle
Cleavage:
Perfect
Perfect parallel to (100)and good parallel to (010)
Perfect parallel to (100)and good parallel to (010)
Density:
3.50(2) g/cm3 (Measured) 3.509 g/cm3 (Calculated)
Comment:
Measured using flotation method in Clerici solution
Optical Data of Vajdakite
Type:
Biaxial (+)
RI values:
nα = 1.757(2) nβ = 1.778(2) nγ = 2.04(1)
2V:
Calculated: 35.1°
Max. Birefringence:
δ = 0.283
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
Pleochroism:
Visible
Comments:
X~Y = light gray to light greenish gray, Z = yellowish gray
Comments:
X || b, Z ^ c = 12 deg.
Chemistry of Vajdakite
Mindat Formula:
[(Mo6+O2)2(H2O)2As3+2O5] · 3H2O
Element Weights:
Elements listed:
Crystallography of Vajdakite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P21/c
Cell Parameters:
a = 7,0515(6) Å, b = 12.0908(9) Å, c = 12.2190(14) Å
β = 101.268(9)°
β = 101.268(9)°
Ratio:
a:b:c = 0.579 : 1 : 1.011
Unit Cell V:
1,014.23 ų (Calculated from Unit Cell)
Z:
4
Morphology:
acicular to lath-shaped crystals to 0.5 mm; in divergent sprays and crusts.
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
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
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View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
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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) |
|---|---|---|---|---|---|---|---|
| 0002870 | Vajdakite | Ondrus P, Skala R, Cisarova I, Veselovsky F, Fryda J, Cejka J (2002) Description and crystal structure of vajdakite, [(MoO2)2(H2O)2As2O5].H2O - a new mineral from Jachymov, Czech Republic American Mineralogist 87 983-990 |  | 2002 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.046 Å | (100) |
| 3.324 Å | (59) |
| 6.915 Å | (26) |
| 2.264 Å | (19) |
| 3.457 Å | (16) |
| 2.624 Å | (15) |
| 3.819 Å | (10) |
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 Vajdakite
General Appearance of Type Material:
Minute acicular crystals or continuous crusts
Place of Conservation of Type Material:
Mineralogical collection, National Museum, Prague, Czech Republic (P1p 19/98)
Associated Minerals at Type Locality:
Synonyms of Vajdakite
Other Language Names for Vajdakite
Common Associates
Associations Based on Photo Data:
| 2 photos of Vajdakite associated with Nickelhexahydrite | Ni2+(H2O)6(SO4) |
| 1 photo of Vajdakite associated with Scorodite | Fe3+AsO4 · 2H2O |
Related Minerals - Strunz-mindat Grouping
| 4.JC.05 | Cafarsite | Ca5.9Mn1.7Fe3Ti3(AsO3)12 · 4-5H2O |
| 4.JC.10 | Lazarenkoite | (Ca,Fe2+)Fe3+As3+3O7 · 3H2O |
| 4.JC.15 | Rouseite | Pb2Mn2+[AsO3]2 · 2H2O |
Other Information
Notes:
Slightly soluble in water
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 Vajdakite
mindat.org URL:
https://www.mindat.org/min-7053.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Vajdakite
Reference List:
Ondruš, P., Veselovský, F., Skála, R., Cisařová, I., Hloušek, J., Frýda, J., Vavřín, I., Čejka, J., Gabašová, A. (1997) New naturally occurring phases of secondary origin from Jáchymov (Joachimsthal) Journal of the Czech Geological Society, 42 (4) 77-108 [as unnamed phase]
Ondruš, Petr, Skála, Roman, Císařová, Ivana, Veselovský, František, Frýda, Jiří, Čejka, Jiří (2002) Description and crystal structure of vajdakite, [(Mo6+O2)2(H2O)2As3+2O5]·H2O—A new mineral from Jáchymov, Czech Republic. American Mineralogist, 87 (7) 983-990 doi:10.2138/am-2002-0722
Mandarino, Joseph A. (2003) New minerals. The Canadian Mineralogist, 41 (5) 1309-1319 doi:10.2113/gscanmin.41.5.1309
Ondruš, P., Veselovský, F., Gabašová, A., Hloušek, J., Šrein, V. (2003) Supplement to secondary and rock-forming minerals of the Jáchymov ore district. Journal of the Czech Geological Society, 48 (3-4) 149-155
Localities for Vajdakite
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.
Czech Republic (TL) | |
| Ondruš et al. (2002) |
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Svornost Mine, Jáchymov, Karlovy Vary District, Karlovy Vary Region, Czech Republic