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Betpakdalite-CaMg
A valid IMA mineral species
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About Betpakdalite-CaMg
Formula:
[Ca2(H2O)17Mg(H2O)6][Mo8As2Fe3+3O36(OH)]
Colour:
Yellow
Lustre:
Sub-Adamantine, Vitreous
Hardness:
3½
Specific Gravity:
2.98
Crystal System:
Monoclinic
Member of:
Name:
First recognized as a potential hypothetical member of the betpakdalite group (IMA 10-E). In 2012 it was approved by IMA as a valid species.
Unique Identifiers
Mindat ID:
41944
Long-form identifier:
mindat:1:1:41944:4
IMA Classification of Betpakdalite-CaMg
Approved
IMA Formula:
[Ca2(H2O)17Mg(H2O)6][Mo6+8As5+2Fe3+3O36(OH)]
Approval year:
2011
First published:
2012
Classification of Betpakdalite-CaMg
8.DM.
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
M : With large and medium-sized cations, (OH, etc.):RO4 > 2:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
M : With large and medium-sized cations, (OH, etc.):RO4 > 2:1
Mineral Symbols
As of 2021 there are now IMAâCNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Bpd-CaMg | IMAâCNMNC | Warr, L.N. (2021). IMAâCNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Betpakdalite-CaMg
Sub-Adamantine, Vitreous
Transparency:
Transparent
Colour:
Yellow
Streak:
Colorless to very pale yellow
Hardness:
3½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{001}
{001}
Fracture:
Irregular/Uneven
Density:
2.98(4) g/cm3 (Measured) 2.944 g/cm3 (Calculated)
Optical Data of Betpakdalite-CaMg
Type:
Biaxial (+)
RI values:
nα = 1.818(3) nβ = 1.824(3) nγ = 1.846(3)
2V:
Measured: 55° (2), Calculated: 55.7°
Max. Birefringence:
δ = 0.028
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 ”m 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 ”m 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, strong
Pleochroism:
Non-pleochroic
Chemistry of Betpakdalite-CaMg
Mindat Formula:
[Ca2(H2O)17Mg(H2O)6][Mo8As2Fe3+3O36(OH)]
Element Weights:
Crystallography of Betpakdalite-CaMg
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 19.5336(7) Å, b = 11.0637(4) Å, c = 15.2559(11) Å
β = 131.528(9)°
β = 131.528(9)°
Ratio:
a:b:c = 1.766 : 1 : 1.379
Unit Cell V:
2468.3 Ă
Âł
Morphology:
Pseudo-octaedra. Forms observed: {001}, {1-10} and [20-1}.
Twinning:
Uncommon. Contact twins on (001) by rotation of 120° about [102] and as pentetration twins by rotation of 120° about [102].
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 11.568 Ă | (25) |
| 8.971 Ă | (100) |
| 7.341 Ă | (34) |
| 3.656 Ă | (33) |
| 3.143 Ă | (26) |
| 2.965 Ă | (44) |
| 2.817 Ă | (35) |
| 2.662 Ă | (31) |
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 Betpakdalite-CaMg
General Appearance of Type Material:
Yellow pseudo-octaedra (up to ~1mm) included in and on scorodite
Place of Conservation of Type Material:
Natural History Museum of Los Angeles County, Los Angeles, California, USA, catalogue numbers 63327 and 63328
Associated Minerals at Type Locality:
Synonyms of Betpakdalite-CaMg
Other Language Names for Betpakdalite-CaMg
Dutch:Betpakdalite-CaMg
German:Betpakdalit-CaMg
Relationship of Betpakdalite-CaMg to other Species
Member of:
Other Members of Betpakdalite Group:
| Betpakdalite-CaCa | [Ca2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O36(OH)] | Mon. 2/m : B2/m |
| Betpakdalite-FeFe | [Fe3+2 (H2O)15(OH)2Fe3+(H2O)6][Mo8As2Fe3+3O37] | Mon. 2/m : B2/m |
| Betpakdalite-NaCa | [Na2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3] | Mon. 2/m : B2/m |
| Betpakdalite-NaNa | [Na2(H2O)16Na(H2O)6][Mo8As2Fe3+3O33(OH)4] | Mon. 2/m : B2/m |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.DM. | Tomsquarryite | NaMgAl3(PO4)2(OH)6 · 8H2O |
| 8.DM. | Elliottite | NaMgAl3(PO4)2F6 · 9H2O |
| 8.DM. | Betpakdalite-FeFe | [Fe3+2 (H2O)15(OH)2Fe3+(H2O)6][Mo8As2Fe3+3O37] |
| 8.DM. | Penriceite | [Mg(H2O)6][Na(H2O)2Al3(PO4)2F6] · H2O |
| 8.DM. | Chinnerite | [Mg(H2O)6]Na(H2O)2Al3(PO4)2F6 |
| 8.DM. | Sarrochite | [Ca4(H2O)38][Mo8P2Fe3+3O37(OH)] |
| 8.DM.05 | Esperanzaite | NaCa2Al2(AsO4)2(OH)F4 · 2H2O |
| 8.DM.05 | Morinite | NaCa2Al2(PO4)2(OH)F4 · 2H2O |
| 8.DM.10 | Alexshubnikovite | Ca2Cu9(AsO4)4(OH)9Cl(H2O)8 · 2H2O |
| 8.DM.10 | Tangdanite | Ca2Cu9(AsO4)4(SO4)0.5(OH)9 · 9H2O |
| 8.DM.10 | Tyrolite | Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O |
| 8.DM.15 | Melkovite | [Ca2(H2O)15Ca(H2O)6][Mo8P2Fe3+3O36(OH)] |
| 8.DM.15 | Betpakdalite-NaCa | [Na2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3] |
| 8.DM.15 | Betpakdalite-CaCa | [Ca2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O36(OH)] |
| 8.DM.20 | Phosphovanadylite-Ba | Ba[V4+4P2O8(OH)8] · 12H2O |
| 8.DM.20 | Phosphovanadylite-Ca | Ca[V4+4P2O12(OH)4] · 12H2O |
| 8.DM.25 | Yukonite | Ca3Fe3+(AsO4)2(OH)3 · 5H2O |
| 8.DM.30 | Uduminelite | Ca3Al8(PO4)2O12 · 2H2O |
| 8.DM.35 | Aldermanite | [Mg(H2O)6][Na(H2O)2Al3(PO4)2(OH,F)6] · H2O |
| 8.DM.35 | 'Azovskite' | Fe3+3(PO4)(OH)6 or near |
| 8.DM.35 | Delvauxite | CaFe4(PO4,SO4)2(OH)8 · 4-6H2O not confirmed |
| 8.DM.40 | Santafeite | (Na,Ca,Sr)12(Mn2+,Fe3+,Al,Mg)8Mn4+8(VO4)16(OH,O)20 · 8H2O |
| 8.DM.55 | Tapiaite | Ca5Al2(AsO4)4(OH)4 · 12H2O |
| 8.DM.60 | Alcantarillaite | [Fe3+0.5(H2O)4][CaAs3+2(Fe3+2.5W6+0.5)(AsO4)2O7] |
Other Information
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 Betpakdalite-CaMg
mindat.org URL:
https://www.mindat.org/min-41944.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
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References for Betpakdalite-CaMg
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2011) New minerals and nomenclature modifications approved in 2011, CNMNC Newsletter No. 10. Mineralogical Magazine, 75 (5) 2549-2561 doi:10.1180/minmag.2011.075.5.2549
Kampf, A. R., Mills, S. J., Rumsey, M. S., Dini, M., Birch, W. D., Spratt, J., Pluth, J. J., Steele, I. M., Jenkins, R. A., Pinch, W. W. (2012) The heteropolymolybdate family: structural relations, nomenclature scheme and new species. Mineralogical Magazine, 76 (5) 1175-1207 doi:10.1180/minmag.2012.076.5.09
Localities for Betpakdalite-CaMg
Showing 9 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
â - 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.
Australia | |
| Rankin et al. (2002) |
France | |
| Christophe Boutry collection |
Germany | |
| FĂ€rber (n.d.) |
Italy | |
| Gentile et al. (2023) |
| Marco Bonifazi collection |
Morocco | |
| Georges FAVREAU collection & EDX ... |
Namibia (TL) | |
| Williams et al. (2011) +1 other reference |
Russia | |
| Kasatkin et al. (2014) |
UK | |
| Rumsey (2022) |
Quick NavTopAbout Betpakdalite-CaMgUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia