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Coutinhoite

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Formula:
ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))
System:
Orthorhombic
Colour:
yellow
Hardness:
2
Name:
For Jose Moacyr Vianna Couthino, Professor of Mineralogy, Institute of Geological Sciences, Sao Paulo, Brazil.
This page provides mineralogical data about Coutinhoite.

Classification of Coutinhoite

Approved 2003
9.AK.30

9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
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http://www.mindat.org/min-26529.html
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First Recorded Occurrence of Coutinhoite

General Appearance of First Recorded Material:
Fine grained yellow massive material. Flaky crystals 10 microns long by 0.5 microns thick.
Place of Conservation of First Recorded Material:
Geoscience Museum, Institute of Geosciences, University of Sao Paulo, Brazil
Year of Discovery:
1997
Geological Setting of First Recorded Material:
Secondary hydrothermal mineral in a pegmatite

Physical Properties of Coutinhoite

Waxy, Silky
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
yellow
Streak:
yellow
Hardness (Mohs):
2
Tenacity:
Brittle

Crystallography of Coutinhoite

Crystal System:
Orthorhombic
Cell Parameters:
a = 14.1675Å, b = 14.1935Å, c = 35.754Å
Ratio:
a:b:c = 0.998 : 1 : 2.519
Unit Cell Volume:
V 7189.7 ų
Z:
16
Morphology:
Scales and flakes
Twinning:
Not observed

Optical Data of Coutinhoite

Type:
Biaxial (-)
RI values:
nα = 1.620 nβ = 1.627 nγ = 1.629
2V:
Measured: 40° , Calculated: 56°
Max Birefringence:
δ = 0.009
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Moderate
Dispersion:
strong r
Pleochroism:
Visible
Comments:
Z>Y, X yellow

Chemical Properties of Coutinhoite

Formula:
ThxBa(1-2x)(UO2)2Si5O13 · (H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))
All elements listed in formula:

Relationship of Coutinhoite to other Species

9.AK.05Soddyite(UO2)2SiO4 · 2H2O
9.AK.10CuprosklodowskiteCu(UO2)2[HSiO4]2 · 6H2O
9.AK.10Oursinite(Co,Mg)(UO2)2[HSiO4]2 · 6H2O
9.AK.10SklodowskiteMg(UO2)2[HSiO4]2 · 5H2O
9.AK.15Boltwoodite(K,Na)(UO2)[HSiO4] · 0.5H2O
9.AK.15KasolitePb(UO2)[SiO4] · H2O
9.AK.15Natroboltwoodite(H3O)(Na,K)UO2SiO4 · H2O
9.AK.15Uranophane-βCa(UO2)2(HSiO4)2 · 5H2O
9.AK.15UranophaneCa(UO2)2[HSiO4]2 · 5H2O
9.AK.15Beta-Uranophane
9.AK.20SwamboiteUH6(UO2)6(SiO4)6 · 30H2O
9.AK.25HaiweeiteCa(UO2)2[Si5O12(OH)2] · 6H2O
9.AK.25MetahaiweeiteCa(UO2)2Si6O15 · nH2O
9.AK.25Ranquilite
9.AK.30WeeksiteK2(UO2)2(Si5O13) · 4H2O
9.AK.35Ursilite(Mg,Ca)4(UO2)4(Si2O5)5.5(OH)5 · 13H2O
9.AK.35MagnioursiliteMg4(UO2)4(Si2O5)5(OH)6 · 20H2O
9.AK.35CalcioursiliteCa4(UO2)4(Si2O5)5(OH)6 · 15H2O
9.AK.40UranosiliteUO3 · 7SiO2

Other Names for Coutinhoite

Name in Other Languages:

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.

References for Coutinhoite

Reference List:
Atencio, D., Carvalho, F. M. S. & Matioli, P. A. (2004): Coutinhoite, a new thorium uranyl silicate hydrate, from Urucum mine, Galileia, Minas Gerais, Brazil. American Mineralogist: 89: 721-724.

Internet Links for Coutinhoite

Localities for Coutinhoite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
Brazil
 
  • Minas Gerais
    • Doce valley
      • Galiléia
American Mineralogist (2004): 89(5-6): 721-724.
Mineral and/or Locality  
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