Vajdakite Mineral Data

General Vajdakite Information

Chemical Formula:

[(MoO2)2(H2O)2As2O5]•(H2O)

Composition:

Molecular Weight = 535.57 gm

Molybdenum 34.04 % Mo 51.06 % MoO₃

Arsenic 27.98 % As 36.94 % As₂O₃

Hydrogen 1.24 % H 11.10 % H₂O

Oxygen 36.74 % O

______ ______

100.00 % 99.10 % = TOTAL OXIDE

Empirical Formula:

Mo_1.9As₂O₉•3.3(H₂O)

Environment:

On fractures in proximity to an ore vein. Formed by concentrated sulfuric acid in the presence of As2O3.

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Jachymov, NW Bohemia, Czech Republic. Link to MinDat.org Location Data.

Name Origin:

Named for Josef Vajdak (1930-), for his significant contribution in the study of minerals in the Jachymov ore district.

Synonym:

IMA1998-031

Vajdakite Image

Images:

Vajdakite

Comments: Scanning electron microscope photograph of aggregate of acicular vajdakite crystals (AmMin, 87:984).
Location: JÃ¡chymov, NW Bohemia, Czech Republic. Scale: 300x magnification.
© American Mineralogist

Vajdakite Crystallography

Axial Ratios:

a:b:c =0.5832:1:1.0106

Cell Dimensions:

a = 7.0515, b = 12.0908, c = 12.219, Z = 4; beta = 101.268° V = 1,021.69 Den(Calc)= 3.48

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/c

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 6.046(1)(020), 3.324(0.59)(023), 6.915(0.26)(100),2.264(0.19)(310), 3.457(0.16)(200), 2.624(0.15)(230), 2.593(0.12), 3.819(0.1)(031),

Physical Properties of Vajdakite

Cleavage:

{100} Perfect, {010} Good

Color:

Green, Greenish gray.

Density:

3.5

Diaphaneity:

Translucent

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Luster:

Vitreous (Glassy)

Streak:

light grayish green

Optical Properties of Vajdakite

Gladstone-Dale:

CI meas= 0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.004 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2466,KPDmeas= 0.2452,KC= 0.2456
Ncalc = 1.85 - 1.86

Optical Data:

Biaxial (+), a=1.757, b=1.778, g=2.04, bire=0.2830

Calculated Properties of Vajdakite

Electron Density:

Bulk Density (Electron Density)=3.28 gm/cc
note: Specific Gravity of Vajdakite =3.50 gm/cc.

Fermion Index:

Fermion Index = 0.08
Boson Index = 0.92

Photoelectric:

PE_Vajdakite= 74.94 barns/electron
U=PE_Vajdakite x rElectron Density= 245.66 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Vajdakite is Not Radioactive

Vajdakite Classification

Dana Class:

49.04.08.01 (49)Basic and Hydrated Molybdates and Tungstates

(49.04)(Compound Anions)

(49.04.08)Dana Group

49.04.08.01 Vajdakite! [(MoO2)2(H2O)2As2O5]•(H2O) P 2₁/c 2/m

Strunz Class:

04.JC.20 04 - OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodate

04.J - Arsenites, Antimonites, Bismuthites, Sulfites,

04.JC -Arsenites, antimonites, bismuthites; without additional anions, with H2O

04.JC.20 Vajdakite! [(MoO2)2(H2O)2As2O5]•(H2O) P 2₁/c 2/m

Other Vajdakite Information

References:

NAME( AmMin, Vol 87, p 983) PHYS. PROP.(AmMin, Vol 87, p 983) OPTIC PROP.(AmMin, Vol 87, p 983)

See Also:

Links to other databases for Vajdakite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Vajdakite

[(MoO2)2(H2O)2As2O5]•(H2O)
Dana No: 49.04.08.01 Strunz No: 04.JC.20
Locality:

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