Bicapite
A valid IMA mineral species
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Formula:
[KNa2Mg2(H2O)25][H2PV5+12O40(V5+O)2]
Colour:
dark red-brown, often appearing black
Lustre:
Vitreous
Hardness:
1½
Specific Gravity:
2.44
Crystal System:
Tetragonal
Name:
Only known mineral with a structure based on a bicapped Keggin anion.
Structural relationship to kegginite. Unique combination of elements.
Interesting due to containing untypical vanadyl ion VO3+ with pentavalent vanadium, as opposed to the usual (for minerals) VO2+ one with tetravalent vanadium.
Interesting due to containing untypical vanadyl ion VO3+ with pentavalent vanadium, as opposed to the usual (for minerals) VO2+ one with tetravalent vanadium.
Unique Identifiers
Mindat ID:
53141
Long-form identifier:
mindat:1:1:53141:8
GUID
(UUID V4):
(UUID V4):
43799a9b-8951-4d3b-9798-e75c00443ede
IMA Classification of Bicapite
Approved
Approval year:
2018
First published:
2019
Type description reference:
Classification of Bicapite
8.FD.10
8 : PHOSPHATES, ARSENATES, VANADATES
F : Polyphosphates, Polyarsenates, [4]-Polyvanadates
D : Polyphosphates, etc., with OH and H2O
8 : PHOSPHATES, ARSENATES, VANADATES
F : Polyphosphates, Polyarsenates, [4]-Polyvanadates
D : Polyphosphates, etc., with OH and H2O
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Bic | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Bicapite
Vitreous
Transparency:
Transparent
Colour:
dark red-brown, often appearing black
Streak:
orange
Hardness:
1½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Very Good
{100}
{100}
Density:
2.44(2) g/cm3 (Measured)
Optical Data of Bicapite
Type:
Uniaxial (+)
RI values:
nω = 1.785(5) nε = 1.810
Max Birefringence:
δ = 0.025
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
Pleochroism:
Weak
Comments:
Red-brown; E > O
Chemistry of Bicapite
Mindat Formula:
[KNa2Mg2(H2O)25][H2PV5+12O40(V5+O)2]
Crystallography of Bicapite
Crystal System:
Tetragonal
Class (H-M):
4/m - Dipyramidal
Space Group:
I4/m
Cell Parameters:
a = 11.545(1) Å, c = 20.546(1) Å
Ratio:
a:c = 1 : 1.78
Unit Cell V:
2738.3 ų
Z:
2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.14 Å | (100) |
| 5.037 Å | (10) |
| 4.348 Å | (10) |
| 4.142 Å | (8) |
| 2.978 Å | (29) |
| 2.809 Å | (11) |
| 2.583 Å | (11) |
| 1.820 Å | (8) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47e : [Vanadates, chromates, manganates] | |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 55 : Anthropogenic mine minerals |
Type Occurrence of Bicapite
General Appearance of Type Material:
square tablets up to about 0.2 mm on edge
Place of Conservation of Type Material:
Cotypes: the mineralogical collections of the Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA, catalogue numbers 66915 and 66916
Associated Minerals at Type Locality:
Reference:
Kampf, A. R., Hughes, J. M., Nash, B. P., Marty, J. (2019) Bicapite, KNa2Mg2 (H2PV5+ 14 O42)· 25H2O, a new polyoxometalate mineral with a bicapped Keggin anion from the Pickett Corral mine, Montrose County, Colorado, USA. American Mineralogist: 104(12): 1851-1856.
Synonyms of Bicapite
Related Minerals - Strunz-mindat Grouping
| 8.FD.05 | Volborthite | Cu3(V2O7)(OH)2 · 2H2O |
| 8.FD.05 | Martyite | Zn3(V2O7)(OH)2 · 2H2O |
| 8.FD.05 | Karpenkoite | Co3(V2O7)(OH)2 · 2H2O |
| 8.FD.10 | Vanarsite | NaCa12(As3+V5+8.5V4+3.5As5+6O51)2 · 78H2O |
| 8.FD.10 | Packratite | Ca11(As3+V5+10V4+2As5+6O51)2 · 83H2O |
| 8.FD.10 | Morrisonite | Ca11(As3+V4+2V5+10As5+6O51)2 · 78H2O |
| 8.FD.10 | Gatewayite | Ca6(As3+V4+3 V5+9As5+6O51) · 31H2O |
| 8.FD.10 | Kegginite | Pb3Ca3[AsV12O40(VO)] · 20H2O |
| 8.FD.10 | Lumsdenite | NaCa3Mg2(As3+V4+2V5+10As5+6O51) · 45H2O |
| 8.FD.15 | Chinchorroite | Na2Mg5(As2O7)2(AsO3OH)2(H2O)10 |
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 Bicapite
mindat.org URL:
https://www.mindat.org/min-53141.html
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References for Bicapite
Reference List:
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2018) CNMNC Newsletter 45, New minerals and nomenclature modifications approved in 2018. Mineralogical Magazine, 82 (5) 1225-1232 doi:10.1180/mgm.2018.160
Localities for Bicapite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - 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.
USA (TL) | |
| Mineralogical Magazine +3 other references |
