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About VajdakiteHide

Josef Vajdak
[(Mo6+O2)2(H2O)2As3+2O5] · 3H2O
Green to grey-green
Specific Gravity:
Crystal System:
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).

Classification of VajdakiteHide

First Published:

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

Physical Properties of VajdakiteHide

Green to grey-green
Perfect parallel to (100)and good parallel to (010)
3.50(2) g/cm3 (Measured)    3.509 g/cm3 (Calculated)
Measured using flotation method in Clerici solution

Optical Data of VajdakiteHide

Biaxial (+)
RI values:
nα = 1.757(2) nβ = 1.778(2) nγ = 2.040(1)
Calculated: 35.1°
Max Birefringence:
δ = 0.283
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
r > v
X~Y = light gray to light greenish gray, Z = yellowish gray
X || b, Z ^ c = 12 deg.

Chemical Properties of VajdakiteHide

[(Mo6+O2)2(H2O)2As3+2O5] · 3H2O
IMA Formula:
(Mo6+O2)2As3+2O5 · 3H2O

Crystallography of VajdakiteHide

Crystal System:

Crystal StructureHide

Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0002870VajdakiteOndrus 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 87 983-99020020293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
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)

Type Occurrence of VajdakiteHide

General Appearance of Type Material:
Minute acicular crystals or continuous crusts
Associated Minerals at Type Locality:
Ondruš, P., Skála, R., Císařová, I., Veselovský, F., Frýda, J., Cejka, J. (2002) Description and crystal structure of vajdakite, [(Mo6+O2)2(H2O)2As3+2O5]·H2O - a new mineral from Jáchymov, Czech Republic. American Mineralogist: 87: 983-990.

Synonyms of VajdakiteHide

Other Language Names for VajdakiteHide


Common AssociatesHide

Associated Minerals Based on Photo Data:
2 photos of Vajdakite associated with Nickelhexahydrite(Ni,Mg,Fe)SO4 · 6H2O

Related Minerals - Nickel-Strunz GroupingHide

4.JC.05CafarsiteCa5.9Mn1.7Fe3Ti3(AsO3)12 · 4-5H2OIso. m3 (2/m 3) : Pn3
4.JC.10Lazarenkoite(Ca,Fe2+)Fe3+As3+3O7 · 3H2OOrth.
4.JC.15RouseitePb2Mn2+[AsO3]2 · 2H2OTric.

Other InformationHide

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.

References for VajdakiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Ondruš, P., Veselovský, F., Skála, R., Císarová, I., Hloušek, J., Frýda, J., Vavrín, I., Čejka, J. and Gabašová, A. (1997) New naturally occurring phases of secondary origin from Jáchymov (Joachimsthal). Journal of the Czech Geological Society: 42: 77-107. [as unnamed phase]
Ondruš, P., Skála, R., Císařová, I., Veselovský, F., Frýda, J., Cejka, J. (2002) Description and crystal structure of vajdakite, [(Mo6+O2)2(H2O)2As3+2O5]·H2O - a new mineral from Jáchymov, Czech Republic. American Mineralogist: 87: 983-990.
Mandarino, J.A. (2003) New minerals. The Canadian Mineralogist: 41: 1309-1319.
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: 149-155.

Internet Links for VajdakiteHide

Localities for VajdakiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Czech Republic (TL)
  • Karlovy Vary Region
    • Karlovy Vary District
      • Jáchymov
Ondruš, P., Skála, R., Císařová, I., Veselovský, F., Frýda, J., Cejka, J. (2002) Description and crystal structure of vajdakite, [(Mo6+O2)2(H2O)2As3+2O5]·H2O - a new mineral from Jáchymov, Czech Republic. American Mineralogist: 87: 983-990.; Lapis 2002(7/8), 62
Mineral and/or Locality  
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