Finchite
A valid IMA mineral species
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About Finchite
USGS scientist Warren Finch.
Formula:
Sr(UO2)2(V2O8) · 5H2O
Colour:
golden yellow
Lustre:
Pearly
Hardness:
2
Specific Gravity:
4.352 (Calculated)
Crystal System:
Orthorhombic
Member of:
Name:
In honor of USGS scientist Warren Finch (1924— July 21, 2014), whose career had been defined by the study of uranium and the exploration for sources of it. In fact, not only did he inaugurate a program at USGS devoted to uranium and thorium, he was recognized internationally for his expertise. For decades, Warren served the International Atomic Energy Agency as the U.S. representative and technical expert in the areas of uranium resources, uranium resource estimation, and particularly the geology of sandstone-hosted uranium deposits. He also wrote definitive studies of uranium that are still cited today.
The Sr analogue of francevillite. Unique combination of elements.
Uranyl vanadate sheets in the structure have the francevillite topology.
Due to, i.a., insolubility, stands for a possible immobilization species for uranium and the especially dangerous radionuclide 90Sr.
Uranyl vanadate sheets in the structure have the francevillite topology.
Due to, i.a., insolubility, stands for a possible immobilization species for uranium and the especially dangerous radionuclide 90Sr.
Unique Identifiers
Mindat ID:
52152
Long-form identifier:
mindat:1:1:52152:7
Similar Names
| Pinchite | A valid IMA mineral species | Hg52+Cl2O4 |
| Winchite | A valid IMA mineral species - grandfathered | ◻{CaNa}{Mg4Al}(Si8O22)(OH)2 |
| Winchite (of Fermor) | A synonym of Ferri-winchite | ◻[CaNa][Mg4(Fe3+,Al)]Si8O22(OH)2 |
| Winchite (of Leake) |
Classification of Finchite
Francevillite sheet topology
Finchite contains the francevillite sheet topology.
IMA Classification of Finchite
Approved
Approval history:
IMA2017-052
4.HB.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
H : V[5,6] Vanadates
B : Uranyl Sorovanodates
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 |
|---|---|---|
| Fin | 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 Finchite
Pearly
Transparency:
Transparent
Colour:
Golden yellow
Streak:
Light yellow
Hardness:
2 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
(001)
(001)
Parting:
None observed
Fracture:
Irregular/Uneven
Density:
4.352 g/cm3 (Calculated)
Optical Data of Finchite
Type:
Biaxial (-)
RI values:
nα = 1.70(1) nβ = 1.85(1) nγ = 1.90(1)
2V:
Measured: 53° (1), Calculated: 56°
Max. Birefringence:
δ = 0.200
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.
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.
Surface Relief:
Moderate
Dispersion:
r < v slight
Comments:
X = colorless, Y = Z = yellow
Chemistry of Finchite
Mindat Formula:
Sr(UO2)2(V2O8) · 5H2O
Element Weights:
Chemical Analysis
Oxide wt%:
| 1 | |
|---|---|
| SrO | 10.14 % |
| CaO | 0.41 % |
| BaO | 0.17 % |
| PbO | 0.26 % |
| UO2 | 59.9 % |
| V2O5 | 21.1 % |
| H2O (by stoichiometry) | 9.90 % |
| As2O5 | 0.01 % |
| P2O5 | 0.02 % |
| Total: | 101.91 % |
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Sr0.89Ca0.07Ba0.01Pb0.01)(U0.953O2)2[V2.11O8].5H2O |
| 2 | (1) (Sr0.88K0.17Ca0.10Mg0.07Al0.03Fe0.02)Σ1.20(UO2)2(V2.08O8)·5H2O (Sulfur Springs Draw); (2) (Sr0.50Ca0.28Ba0.22K0.05)Σ0.94(U0.99O2)2(V2.01O8)·5H2O |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Globe Hill Mine, Globe Hill, Cripple Creek Mining District, Teller County, Colorado, USA | This material was collected by geologist Brad Bowman, I believe in the 1980s or possibly early 1990s. He sent me a set of specimens because he thought they might represent a new mineral. EPMA analyses (average of 7 spots; March 1996) is given above. Normalization is to ∑cations = 5; H2O is calculated by stoichiometry, assuming full hydration (5 H2O). The crystals occur in an extensively hydrothermally altered felsic volcanic (phonolite or trachyte?), associated with celestite, fluorite, and Fe-oxides. Platey crystals up to 2-3 mm occurred in some samples of the rock, but unfortunately many of the best specimens were lost when the university janitorial staff mistook the box of samples adjacent to the trash can as garbage and threw it away (grrr); it's possible Brad may still have some nicer samples. The original locality is apparently no longer accessible, as it was reportedly filled in during subsequent mining operations. Attempts to determine the structure on this Globe Hill material back in 1996 were unsuccessful, in part due to the challenge of all of the heavy elements present, and a suspicion that the crystals were twinned. | |
| 2 | Sulfur Springs Draw, Lamesa, Martin County, Texas, USA | by EPMA, based on 17 O atoms per formula unit |
Crystallography of Finchite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 10.363(6) Å, b = 8.498(5) Å, c = 16.250(9) Å
Ratio:
a:b:c = 1.219 : 1 : 1.912
Unit Cell V:
1,431.05 ų (Calculated from Unit Cell)
Z:
4
Comment:
Space Group = Pcan
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.13 Å | (75) |
| 4.25 Å | (64) |
| 4.06 Å | (100) |
| 3.20 Å | (45) |
| 2.98 Å | (68) |
| 2.94 Å | (47) |
| 2.11 Å | (48) |
| 2.03 Å | (55) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47g : [Halogen-bearing surface weathering minerals] | |
| 47h : [Near-surface oxidized, dehydrated minerals] |
Type Occurrence of Finchite
Co-Type Localities:
General Appearance of Type Material:
blades to 10 μm, diamond shaped crystals
Place of Conservation of Type Material:
Cotype material is deposited in the mineralogical collections of the Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA, catalogue numbers 66476 and 66477
Geological Setting of Type Material:
calcrete uranium deposit
Associated Minerals at Type Locality:
Synonyms of Finchite
Other Language Names for Finchite
Relationship of Finchite to other Species
Member of:
Other Members of Francevillite Group:
| Curienite | Pb(UO2)2(VO4)2 · 5H2O | Orth. mmm (2/m 2/m 2/m) |
| Francevillite | Ba(UO2)2(VO4)2 · 5H2O | Orth. mmm (2/m 2/m 2/m) |
| Fritzscheite | Mn(UO2)2(PO4,VO4)2 · 10H2O (?) | Tet. |
Common Associates
Associations Based on Photo Data:
| 3 photos of Finchite associated with Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 2 photos of Finchite associated with Dolomite | CaMg(CO3)2 |
| 1 photo of Finchite associated with Pandoraite-Ba | BaV4+5V5+2O16 · 3H2O |
| 1 photo of Finchite associated with Celestine | SrSO4 |
| 1 photo of Finchite associated with Pandoraite-Ca | CaV4+5V5+2O16 · 3H2O |
Related Minerals - Strunz-mindat Grouping
| 4.HB.X | Spanoite | Tl2[(UO2)2(V2O8)] |
| 4.HB.05 | Margaritasite | (Cs,K,H3O)2(UO2)2(VO4)2 · H2O |
| 4.HB.05 | Carnotite | K2(UO2)2(VO4)2 · 3H2O |
| 4.HB.10 | Sengierite | Cu2(UO2)2(VO4)2 · 6H2O |
| 4.HB.15 | Francevillite | Ba(UO2)2(VO4)2 · 5H2O |
| 4.HB.15 | Fritzscheite | Mn(UO2)2(PO4,VO4)2 · 10H2O (?) |
| 4.HB.15 | Curienite | Pb(UO2)2(VO4)2 · 5H2O |
| 4.HB.20 | Vanuralite | Al(UO2)2(V2O8)(OH) · 11H2O |
| 4.HB.20 | Metavanuralite | Al(UO2)2(VO4)2(OH) · 8H2O |
| 4.HB.25 | Metatyuyamunite | Ca(UO2)2(VO4)2 · 3H2O |
| 4.HB.25 | Tyuyamunite | Ca(UO2)2(VO4)2 · 5-8H2O |
| 4.HB.30 | Strelkinite | Na2(UO2)2(VO4)2 · 6H2O |
| 4.HB.35 | Uvanite | U6+2V5+6O21 · 15H2O (?) |
| 4.HB.40 | Rauvite | Ca(UO2)2(V10O28) · 16H2O |
| 4.HB.45 | Vandermeerscheite | K2[(UO2)2V2O8] · 2H2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 50.2367% | 12,559,175 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 0.0000% | 0 | 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 Finchite
None
Other Information
Notes:
radioactive
Health Risks:
radioactive; to avoid radon buildup, store in a well-ventilated location.
Internet Links for Finchite
mindat.org URL:
https://www.mindat.org/min-52152.html
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References for Finchite
Localities for Finchite
Showing 3 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.
USA | |
| Frank K. Mazdab collection |
| Hålenius et al. (2017) +2 other references |
| EDS and XRD analysis by Tony Kampf. +2 other references |
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Pandora Mine, La Sal Mining District, San Juan County, Utah, USA