Betpakdalite Mineral Data

Betpakdalite Mineral Data +

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General Betpakdalite Information

Chemical Formula:

[Mg(H2O)6]Ca2(H2O)13[Mo++++++8As+++++2Fe+++3O36(OH)]·4(H2O)

Composition:

Molecular Weight = 2,196.70 gm

Calcium 3.65 % Ca 5.11 % CaO

Magnesium 1.11 % Mg 1.83 % MgO

Iron 7.63 % Fe 10.90 % Fe₂O₃

Molybdenum 34.94 % Mo 52.42 % MoO₃

Arsenic 6.82 % As 10.46 % As₂O₅

Hydrogen 2.16 % H 19.27 % H₂O

Oxygen 43.70 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

MgCa₂Mo₈As₂Fe³⁺₃O₃₆(OH)·23(H₂O)

Environment:

Oxidized Mo-As-Fe ores.

IMA Status:

Approved IMA 1961

Locality:

Bet-Pak-Dal desert, Kazakhstan. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Synonym:

ICSD 30798

PDF 37-434

Betpakdalite Image

Images:

Betpakdalite

Comments: Yellow crust of betpakdalite on quartzite.
Location: Sadisdorf, Erzgebirge, Sachsen, Germany. Scale: 10 x 6 cm.
© Thomas Witzke / Abraxas-Verlag

Betpakdalite Crystallography

Axial Ratios:

a:b:c =1.7659:1:1.3794

Cell Dimensions:

a = 19.531, b = 11.06, c = 15.257, Z = 2; beta = 131.57° V = 2,465.67 Den(Calc)= 2.96

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 8.91(1), 7.3(0.5), 11.49(0.4),

Crystal Structure:

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Cooper M A , Hawthorne F C , The Canadian Mineralogist , 37 (1999) p.61-66, The crystal structure of betpakdalite, and a new chemical formula:, {Mg(H2O)6}Ca2(H2O)13[Mo8As2Fe3O36(OH)](H2O)4

View Additional jPOWD Structure files for Betpakdalite
[1]

Physical Properties of Betpakdalite

Cleavage:

[001] Perfect

Color:

Bright lemon yellow, Greenish yellow.

Density:

2.98 - 3.05, Average = 3.01

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Powdery - Forms a loose, poorly-coherent pulverulent mass.

Hardness:

3 - Calcite

Luster:

Vitreous - Waxy

Optical Properties of Betpakdalite

Gladstone-Dale:

CI meas= -0.051 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.071 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2735,KPDmeas= 0.2685,KC= 0.2555

Optical Data:

Biaxial (+), a=1.782, b=1.797, g=1.85, bire=0.0680, 2V(Calc)=58, 2V(Meas)=60. Dispersion extreme.

Pleochroism (x):

pale yellow.

Pleochroism (y):

greenish yellow.

Pleochroism (z):

green.

Calculated Properties of Betpakdalite

Electron Density:

r_electron=2.91 gm/cc
note: r_Betpakdalite=3.02 gm/cc.

Fermion Index

Fermion Index = 0.09197
Boson Index = 0.90803

Photoelectric:

PE_Betpakdalite= 62.87 barns/electron
U=PE_Betpakdalite x r_electron= 182.77 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Betpakdalite is Not Radioactive

Betpakdalite Classification

Dana Class:

49.4.1.1 (49)Basic and Hydrated Molybdates and Tungstates

(49.4)(Compound Anions)

(49.4.1)Dana Group

49.4.1.1 Betpakdalite [Mg(H2O)6]Ca2(H2O)13[Mo8As2Fe3O36(OH)]·4(H2O) C 2/m 2/m

Strunz Class:

VII/C.33-30 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions, molybdophosphates with [MoO4]2- - [PO4]3- and similar

VII/C.33 - Melkovite - Obradovicite series

VII/C.33-10 Melkovite CaFeH6(MoO4)4(PO4)·6(H2O) Unk. Mono

VII/C.33-20 Sodium-betpakdalite (Na,Ca)3Fe2(As2Mo6O28)·15(H2O) Unk Mono

VII/C.33-30 Betpakdalite [Mg(H2O)6]Ca2(H2O)13[Mo8As2Fe3O36(OH)]·4(H2O) C 2/m 2/m

VII/C.33-40 Obradovicite H4(K,Na)CuFe2(AsO4)(MoO4)5·12(H2O) Pcnm 2/m 2/m 2/m

Other Betpakdalite Information

References:

NAME( Dana8) PHYS. PROP.(AmMin, V85, p266) OPTIC PROP.(Dana8)

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

Betpakdalite

[Mg(H2O)6]Ca2(H2O)13[Mo++++++8As+++++2Fe+++3O36(OH)]·4(H2O)
Dana No: 49.4.1.1 Strunz No: VII/C.33-30
Locality:

Notes: