Thoreaulite
A valid IMA mineral species - grandfathered
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About Thoreaulite
Jacques Thoreau (1885-1973)
Formula:
Sn2+Ta2O6
Minor Pb may replace the divalent Sn.
Colour:
Brown to yellow
Lustre:
Adamantine, Resinous
Hardness:
5½ - 6
Specific Gravity:
7.6 - 7.9
Crystal System:
Monoclinic
Member of:
Name:
Named in 1933 by Henri Buttgenbach in honor of Jacques Thoreau [September 27, 1886 Brussels, Belgium - January 11, 1973 Kessel-Lo, Belgium], Professor of Mineralogy, Université Catholique de Leuvain-UCL, Belgium.
Type Locality:
Isostructural with:
Foordite-Thoreaulite Series.
Thoreaulite was first described by Buttgenbach (1933) from a pegmatite at the Manono Mine, Tanganyika, DR Congo.
Thoreaulite was first described by Buttgenbach (1933) from a pegmatite at the Manono Mine, Tanganyika, DR Congo.
Unique Identifiers
Mindat ID:
3943
Long-form identifier:
mindat:1:1:3943:3
Similar Names
| Theralite | A rock subtype |
| Thraulit | A synonym of Hisingerite |
IMA Classification of Thoreaulite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Sn2+Ta5+2O6
First published:
1933
Classification of Thoreaulite
4.DG.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
G : With large (+- medium-sized) cations; chains of edge-sharing octahedra
Dana 7th ed.:
8.3.10.1
8.3.10.1
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
3 : AB2O6
18.1.21
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
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 |
|---|---|---|
| Tre | 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 Thoreaulite
Adamantine, Resinous
Transparency:
Opaque
Comment:
adamantine on the cleavage
Colour:
Brown to yellow
Streak:
Brown to yellow, slightly greenish
Hardness:
5½ - 6 on Mohs scale
Cleavage:
Perfect
On {100}; on {011} imperfect.
On {100}; on {011} imperfect.
Density:
7.6 - 7.9 g/cm3 (Measured) 7.6(5) g/cm3 (Calculated)
Optical Data of Thoreaulite
Type:
Biaxial (+)
RI values:
nα = 2.39 nβ = 2.42 nγ = 2.52
2V:
Measured: 25° to 35°, Calculated: 60°
Birefringence:
On {100} cleavages = 0.039.
Max. Birefringence:
δ = 0.130
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:
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
Pleochroism:
Non-pleochroic
Chemistry of Thoreaulite
Mindat Formula:
Sn2+Ta2O6
Minor Pb may replace the divalent Sn.
Minor Pb may replace the divalent Sn.
Element Weights:
Elements listed:
Crystallography of Thoreaulite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 17.127(20) Å, b = 4.869(5) Å, c = 5.52(2) Å
β = 91°
β = 91°
Ratio:
a:b:c = 3.518 : 1 : 1.134
Unit Cell V:
460.25 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals rough, prismatic [001].
Twinning:
Lamellar twins, with composition face {010}.
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0015601 | Thoreaulite | Maksimova N V, Ilyukhin V V, Belov N V (1975) Crystal structure of thoreaulite, SaTa2O6 Soviet Physics Doklady 20 528-529 | 1975 | Manono, Katanga, Democratic Republic of the Congo | 0 | 293 | |
| 0000199 | Thoreaulite | Mumme W G (1970) The crystal structure of SnTa2O7, thoreaulite, an example of tin in five-fold coordination American Mineralogist 55 367-377 |  | 1970 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.10 Å | (100) |
| 3.07 Å | (100) |
| 2.857 Å | (80) |
| 2.432 Å | (80) |
| 1.724 Å | (80) |
| 3.59 Å | (60) |
| 3.57 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 26 : Hadean detrital minerals | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Thoreaulite
General Appearance of Type Material:
Coarse crystals reaching several centimeters, without a characteristic shape and resembling wood tin.
Place of Conservation of Type Material:
University of Liège, Liège, Belgium, 2067 and 2068.
Geological Setting of Type Material:
Granite pegmatite (tin bearing)
Associated Minerals at Type Locality:
Synonyms of Thoreaulite
Other Language Names for Thoreaulite
Relationship of Thoreaulite to other Species
Common Associates
Associations Based on Photo Data:
| 10 photos of Thoreaulite associated with Cassiterite | SnO2 |
| 7 photos of Thoreaulite associated with Rankamaite | (Na,K)3(Ta,Nb,Al)11(O,OH)31 |
| 6 photos of Thoreaulite associated with Albite | Na(AlSi3O8) |
| 5 photos of Thoreaulite associated with Lithiotantite | LiTa3O8 |
| 4 photos of Thoreaulite associated with Quartz | SiO2 |
| 3 photos of Thoreaulite associated with Cesplumtantite | (Cs,Na)2(Pb,Sb3+)3Ta8O24 |
| 1 photo of Thoreaulite associated with Simpsonite | Al4Ta3O13(OH) |
| 1 photo of Thoreaulite associated with Lepidolite |
Related Minerals - Strunz-mindat Grouping
| 4.DG.05 | Fersmite | CaNb2O6 |
| 4.DG.05 | Uranopolycrase | (U4+,Y)(Ti,Nb)2O6 |
| 4.DG.05 | Yttrocrasite-(Y) | (Y,Th,Ca,U)(Ti,Fe)2(O,OH)6 |
| 4.DG.05 | Tanteuxenite-(Y) | Y(Ta,Nb,Ti)2(O,OH)6 |
| 4.DG.05 | Loranskite-(Y) | (Y,Ce,Ca)ZrTaO6 (?) |
| 4.DG.05 | Euxenite-(Y) | (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6 |
| 4.DG.05 | Kobeite-(Y) | (Y,U)(Ti,Nb)2(O,OH)6 (?) |
| 4.DG.10 | Yttrotantalite-(Y) | (Y,U,Fe2+)(Ta,Nb)(O,OH)4 |
| 4.DG.10 | Clinofergusonite-(Y) | YNbO4 |
| 4.DG.10 | Clinofergusonite-(Nd) | (Nd,Ce)NbO4 |
| 4.DG.10 | Clinofergusonite-(Ce) | CeNbO4 |
| 4.DG.15 | Foordite | Sn2+Nb2O6 |
| 4.DG.20 | Raspite | Pb(WO4) |
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 Thoreaulite
mindat.org URL:
https://www.mindat.org/min-3943.html
Please feel free to link to this page.
Please feel free to link to this page.
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Mineral Dealers:
References for Thoreaulite
Reference List:
Graham, J.; Thornber, M. R. (1974) The crystal chemistry of complex niobium and tantalum oxides. I. Structural classification of MO2 phases. American Mineralogist, 59 (9-10). 1026-1039
Localities for Thoreaulite
Showing 10 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.
Brazil | |
| Cassedanne et al. (1981) +1 other reference |
China | |
| Deshi Lu (1993) |
DR Congo | |
| Buttgenbach (1947) |
| Uher et al. (2008) | |
| Vanrusselt (2023) |
| Buttgenbach (1933) +1 other reference |
Kazakhstan | |
| Pekov (1998) |
| Voloshin et al. (1983) +1 other reference |
Rwanda | |
| Ann. Soc. Geol. Belgique |
| Bertossa (1968) +1 other reference |
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Ognevka Ta deposit, Ulan District, East Kazakhstan Region, Kazakhstan