Vajdakite Mineral Data

Vajdakite Mineral Data

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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: J?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 - PrismaticH-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),

Crystal Structure:

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Ondrus P , Skala R , Cisarova I , Veselovsky F , Fryda J , Cejka J , American Mineralogist , 87 (2002) p.983-990, Description and crystal structure of vajdakite, [(MoO2)2(H2O)2As2O5].H2O -, a new mineral from Jachymov, Czech Republic

Physical Properties of Vajdakite

Cleavage:

[100] Perfect, [010] Good

Color:

Green, Greenish gray.

Density:

3.5

Diaphaniety:

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

Optical Data:

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

Calculated Properties of Vajdakite

Electron Density:

r_electron=3.28 gm/cc
note: r_Vajdakite=3.50 gm/cc.

Fermion Index

Fermion Index = 0.08686
Boson Index = 0.91314

Photoelectric:

PE_Vajdakite= 74.94 barns/electron
U=PE_Vajdakite x r_electron= 245.66 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Vajdakite is Not Radioactive

Vajdakite Classification

Dana Class:

49.4.8.1 (49)Basic and Hydrated Molybdates and Tungstates

(49.4)(Compound Anions)

(49.4.8)Dana Group

49.4.8.1 Vajdakite ! [(MoO2)2(H2O)2As2O5]·(H2O) P 2₁/c 2/m

Strunz Class:

IV/J.06-25 IV - Oxides

IV/J - Arsenides with [AsO3]3-, [AsO2]-, [As2O5]4- groups and unclassified Arsenides

IV/J.06 - Stenhuggarite - Lazarenkoite series

IV/J.06-10 Stenhuggarite CaFe(AsO2)(AsSbO5) I 4₁ 4

IV/J.06-20 Lazarenkoite CaFeAs3O7·3(H2O) Unk Ortho

IV/J.06-25 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 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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Print or Cut-and-Paste your Vajdakite Specimen Label here :

Vajdakite

[(MoO2)2(H2O)2As2O5]·(H2O)
Dana No: 49.4.8.1 Strunz No: IV/J.06-25
Locality:

Notes: