Obradovicite-KCu
A valid IMA mineral species
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About Obradovicite-KCu
Formula:
[K2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3]
Colour:
Pea-green (RHS 149A)
Lustre:
Sub-Adamantine, Vitreous
Hardness:
2½
Specific Gravity:
3.55
Crystal System:
Orthorhombic
Member of:
Name:
Named obradovicite by Finney et al. (1986) in honor of Martin T. Obradovic, from whose mineral collection the type material came. He graduated from Colorado School of mines in 1953. In 1970 he headed the alumni association in Lima, Peru. The double suffix was added in 2010 by the International Mineralogical Association in a redefinition of this and related species. The double suffix corresponds to the dominant cations in two different types of non-framework cation sites; in this case potassium and copper.
Formerly called obradovicite; redefined in 2010 (IMA 10-E). Both obradovicite-NaCu and obradovicite-KCu was found on the type specimen of "obradovicite".
Unique Identifiers
Mindat ID:
2952
Long-form identifier:
mindat:1:1:2952:6
IMA Classification of Obradovicite-KCu
Approved
IMA status notes:
Renamed by the IMA
IMA Formula:
[K2(H2O)17Cu2+(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3]
Approval year:
1978
First published:
1986
Approval history:
Renamed from obradovicite to obradovicite-KCu in IMA Proposal 10-E (CNMNC Newsletter 7)
Classification of Obradovicite-KCu
7.GB.40
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
G : Molybdates, Wolframates and Niobates
B : With additional anions and/or H2O
49.4.2.1
49 : HYDRATED MOLYBDATES AND TUNGSTATES
4 : Compound Molybdates and Tungstates
49 : HYDRATED MOLYBDATES AND TUNGSTATES
4 : Compound Molybdates and Tungstates
22.5.10
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
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 for Standard |
|---|---|---|
| Obr-KCu | 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 Obradovicite-KCu
Sub-Adamantine, Vitreous
Transparency:
Translucent
Colour:
Pea-green (RHS 149A)
Streak:
Pale pea-green (RHS 149C)
Hardness:
2½ on Mohs scale
Cleavage:
None Observed
Density:
3.55 g/cm3 (Measured) 3.68 g/cm3 (Calculated)
Optical Data of Obradovicite-KCu
Type:
Biaxial (+)
RI values:
nα = 1.790 nβ = 1.798 nγ = 1.811
2V:
Measured: 81° , Calculated: 75.7°
Max. Birefringence:
δ = 0.021
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 µm 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 µm 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:
Moderate
Dispersion:
r> v, extreme
Pleochroism:
Weak
Comments:
Weak yellow pleochroism, Z > X = Y
Chemistry of Obradovicite-KCu
Mindat Formula:
[K2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3]
Element Weights:
Crystallography of Obradovicite-KCu
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pmna
Cell Parameters:
a = 15.046 Å, b = 14.848 Å, c = 11.056 Å
Ratio:
a:b:c = 1.013 : 1 : 0.745
Unit Cell V:
2,469.94 ų (Calculated from Unit Cell)
Z:
4
Morphology:
a{100}, m {110}, and d{011}
Twinning:
None observed.
Comment:
Pnmb
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 10.565 Å | (80) |
| 8.906 Å | (100) |
| 7.424 Å | (80) |
| 5.733 Å | (50) |
| 3.761 Å | (30) |
| 3.686 Å | (40) |
| 3.466 Å | (30) |
| 3.344 Å | (40) |
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 Obradovicite-KCu
General Appearance of Type Material:
dense clusters of platy crystals to 0.1 mm
Place of Conservation of Type Material:
Colorado School of Mines Museum, and National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Geological Setting of Type Material:
on brecciated, slightly leached, vein quartz or on crusts of earthy tan jarosite
Associated Minerals at Type Locality:
Synonyms of Obradovicite-KCu
Other Language Names for Obradovicite-KCu
Relationship of Obradovicite-KCu to other Species
Member of:
Other Members of Obradovicite Group:
| Obradovicite-NaCu | Na2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3] | Orth. mmm(2/m2/m2/m) : Pmna |
| Obradovicite-NaNa | [Na2(H2O)16Na(H2O)6][Mo8As2Fe3+3O33(OH)4] | Orth. |
Related Minerals - Strunz-mindat Grouping
| 7.GB. | Stunorthropite | (NH4)4[Mo2O6(MoO4)2] |
| 7.GB. | Hartkoppeite | Ca4Mn2+Mo6+6As5+4O32(OH)2(H2O)14 · 5H2O |
| 7.GB. | Wangpuite | K3(PO4)(Mo12O36) |
| 7.GB. | Alexearlite | Hg3S2(MoO4) |
| 7.GB. | Ootannite | Th4+2W6+4O16 · 5H2O |
| 7.GB. | Natromolybdite | Na2MoO4 · 2H2O |
| 7.GB. | Marsaalamite-(Y) | Y(MoO4)(OH) |
| 7.GB.05 | Lindgrenite | Cu3(MoO4)2(OH)2 |
| 7.GB.10 | Szenicsite | Cu3(MoO4)(OH)4 |
| 7.GB.15 | 'UM1999-38-WO:CrV' | (V, Cr, W, O, H) [V:Cr:W ratio about 2:1:3] |
| 7.GB.15 | Huenite | Cu4(MoO4)3(OH)2 |
| 7.GB.15 | Cuprotungstite | Cu2(WO4)(OH)2 |
| 7.GB.20 | Phyllotungstite | (H2O,M)x(W,Fe)(O,OH)3 · yH2O (M = Ca, Cs, Pb or K) |
| 7.GB.25 | Rankachite | Ca0.5(V4+,V5+)(W6+,Fe3+)2O8(OH) · 2H2O |
| 7.GB.30 | Ferrimolybdite | Fe2(MoO4)3 · nH2O |
| 7.GB.35 | Mpororoite | WAlO3(OH)3 · 2(H2O) |
| 7.GB.35 | Anthoinite | AlWO3(OH)3 |
| 7.GB.45 | Paramendozavilite | [KAl4(H2O)30][Mo12P6Fe3+6O60(OH)13] |
| 7.GB.45 | Mendozavilite-NaFe | [Na2(H2O)15Fe3+(H2O)6][Mo8P2Fe3+3O35(OH)2] |
| 7.GB.45 | Obradovicite-NaCu | Na2(H2O)17Cu(H2O)6][Mo8As2Fe3+3O34(OH)3] |
| 7.GB.45 | Obradovicite-NaNa | [Na2(H2O)16Na(H2O)6][Mo8As2Fe3+3O33(OH)4] |
| 7.GB.50 | Tancaite-(Ce) | FeCe(MoO4)3 · 3H2O |
| 7.GB.50 | Mendozavilite-NaCu | [Na2(H2O)15Cu(H2O)6][Mo8P2Fe3+3O34(OH)3] |
| 7.GB.50 | Mendozavilite-KCa | [K2(H2O)15Ca(H2O)6][Mo8P2Fe3+3O34(OH)3] |
| 7.GB.60 | Peterandresenite | Mn4Nb6O19 · 14H2O |
| 7.GB.60 | Hansesmarkite | Ca2Mn2Nb6O19 · 20H2O |
| 7.GB.60 | Melcherite | Ba2Na2Mg[Nb6O19] · 6H2O |
| 7.GB.65 | Ichnusaite | Th(MoO4)2 · 3H2O |
| 7.GB.70 | Markascherite | Cu3(MoO4)(OH)4 |
| 7.GB.75 | Nuragheite | Th(MoO4)2 · H2O |
| 7.GB.80 | Ophirite | Ca2Mg4[Zn2Mn3+2(H2O)2(Fe3+W9O34)2] · 46H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 3.4969% | 1,084 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Fluorescence of Obradovicite-KCu
does not fluoresce under SW
Other Information
Notes:
It is insoluble in cold 1:1 HNO3 but dissolves rapidly upon heating, readily soluble in cold 1:1 HCl, rapidly turns dull brick orange in 40% KOH, and is unaffected by 20% NH4OH.
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 Obradovicite-KCu
mindat.org URL:
https://www.mindat.org/min-2952.html
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References for Obradovicite-KCu
Reference List:
Finney, J. J., Williams, S. A., Hamilton, R. D. (1986) Obradovicite, a new complex arsenate-molybdate from Chuquicamata, Chile. Mineralogical Magazine, 50 (356) 283-284 doi:10.1180/minmag.1986.050.356.12
Hawthorne, Frank C., Jambor, John L., Bladh, Kenneth W., Burke, Ernst A. J., Grice, Joel D., Phillips, Don, Roberts, Andrew C., Schedler, Robert A., E., James (1987) New mineral names. American Mineralogist, 72 (9-10) 1023-1028
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2011) New minerals and nomenclature modifications approved in 2010, CNMNC Newsletter No 7. Mineralogical Magazine, 75 (1) 27-31 doi:10.1180/minmag.2011.075.1.27
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 Obradovicite-KCu
Showing 2 localities.
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.
Australia | |
| Kampf et al. (2012) |
Chile (TL) | |
| Finney et al. (1986) +1 other reference |
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Chuquicamata Mine, Chuquicamata District, Calama, El Loa Province, Antofagasta, Chile