Coutinhoite
A valid IMA mineral species
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About Coutinhoite
José Moacyr Vianna Coutinho
Formula:
ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))
Colour:
yellow
Lustre:
Waxy, Silky
Hardness:
2
Specific Gravity:
3.839 (Calculated)
Crystal System:
Orthorhombic
Name:
Named in honor of José Moacyr Vianna Couthino, (April 4, 1924- June 25, 2021), professor of mineralogy and petrography at the Instituto de Geociências (Institute of Geological Sciences) of University of São Paulo, Brazil.
This page provides mineralogical data about Coutinhoite.
Unique Identifiers
Mindat ID:
26529
Long-form identifier:
mindat:1:1:26529:6
Similar Names
| Coutinhite | A synonym of Lanthanite-(La) |
IMA Classification of Coutinhoite
Approved
IMA Formula:
Th4+xBa1-2x(U6+O2)2Si5O13·3H2O
Approval year:
2003
First published:
2004
Classification of Coutinhoite
9.AK.30
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
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 |
|---|---|---|
| Cti | 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 Coutinhoite
Waxy, Silky
Transparency:
Transparent, Translucent
Colour:
Yellow
Streak:
Yellow
Hardness:
2 on Mohs scale
Tenacity:
Brittle
Density:
3.839 g/cm3 (Calculated)
Optical Data of Coutinhoite
Type:
Biaxial (-)
RI values:
nα = 1.620(3) nβ = 1.627(3) nγ = 1.629(3)
2V:
Measured: 40° (5), Calculated: 56°
Max. Birefringence:
δ = 0.009
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:
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:
strong r
Pleochroism:
Visible
Comments:
Z>Y, X yellow
Chemistry of Coutinhoite
Mindat Formula:
ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))
Crystallography of Coutinhoite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Cell Parameters:
a = 14.1675 Å, b = 14.1935 Å, c = 35.754 Å
Ratio:
a:b:c = 0.998 : 1 : 2.519
Unit Cell V:
7189.7 ų
Z:
16
Morphology:
Scales and flakes
Twinning:
Not observed
Comment:
Space Group: Cmmb (probable by analogy to weeksite).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.059 Å | (100) |
| 3.528 Å | (86) |
| 2.904 Å | (78) |
| 3.188 Å | (73) |
| 5.563 Å | (59) |
| 3.287 Å | (57) |
| 3.826 Å | (48) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) | |
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47f : [Uranyl (U⁶⁺) minerals] |
Type Occurrence of Coutinhoite
General Appearance of Type Material:
Fine grained yellow massive material. Flaky crystals 10 microns long by 0.5 microns thick.
Place of Conservation of Type Material:
Museu de Geosciencias, Instituto de Geosciencias, Universidade de Sao Paulo, Rua do Lago, 562, 05505-080, Sao Paulo, SP, Brazil. Catalog number DR523.
Museu Jobas de Ciencias Naturais "Jose Bonifacio de Andrada e Silva," Rua Martim Afonso, 24, Biquinha
Museu Jobas de Ciencias Naturais "Jose Bonifacio de Andrada e Silva," Rua Martim Afonso, 24, Biquinha
Geological Setting of Type Material:
Secondary hydrothermal mineral in a pegmatite
Associated Minerals at Type Locality:
Synonyms of Coutinhoite
Other Language Names for Coutinhoite
Dutch:Coutinhoiet
German:Coutinhoit
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.AK. | 'Orlite' | Pb3(UO2)3(Si2O7)2 · 6H2O |
| 9.AK.05 | Soddyite | (UO2)2SiO4 · 2H2O |
| 9.AK.10 | Sklodowskite | Mg(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Cuprosklodowskite | Cu(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.10 | Oursinite | Co(UO2)2(SiO3OH)2 · 6H2O |
| 9.AK.15 | Parauranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 9.AK.15 | Uranophane | Ca(UO2)2(SiO3OH)2 · 5H2O |
| 9.AK.15 | Natroboltwoodite | Na(UO2)(SiO3OH) · H2O |
| 9.AK.15 | Kasolite | Pb(UO2)(SiO4) · H2O |
| 9.AK.15 | Boltwoodite | (K,Na)(UO2)(SiO3OH) · 1.5H2O |
| 9.AK.20 | Swamboite-(Nd) | Nd0.333[(UO2)(SiO3OH)](H2O)~2.5 |
| 9.AK.25 | Haiweeite | Ca(UO2)2[Si5O12(OH)2] · 6H2O |
| 9.AK.25 | Metahaiweeite | Ca(UO2)2Si6O15 · nH2O |
| 9.AK.30 | Weeksite | K2(UO2)2(Si5O13) · 4H2O |
| 9.AK.30 | Barronite | (◻0.5Ba0.5)(UO2)2Si5O12(OH) · 2H2O |
| 9.AK.35 | Magnioursilite | Mg4(UO2)4(Si2O5)5(OH)6 · 20H2O |
| 9.AK.35 | Calcioursilite | Ca4(UO2)4(Si2O5)5(OH)6 · 15H2O |
| 9.AK.40 | Uranosilite | UO3 · 7SiO2 |
Fluorescence of Coutinhoite
none
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 Coutinhoite
mindat.org URL:
https://www.mindat.org/min-26529.html
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Please feel free to link to this page.
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References for Coutinhoite
Localities for Coutinhoite
Showing 1 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 (TL) | |
| Atencio et al. (2004) |
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Urucum claim, Barra do Cuieté, Conselheiro Pena, Minas Gerais, Brazil