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Coutinhoite

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Formula:
Th
 
x
Ba
 
(1-2x)
(UO
 
2
)
 
2
Si
 
5
O
 
13
· (H
 
2
O)
 
1+y
(0 < x < 0.5 and 0 < y < (2+x))
System:OrthorhombicColour: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

IMA status:Approved 2003
Nickel-Strunz 10th (pending) edition ID:9.AK.30

9 : SILICATES (Germanates)
A : Nesosilicates
K : Uranyl neso- and polysilicates
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Type Occurrence of Coutinhoite

Type Locality:Urucum mine (Tim mine; Córrego do Urucum pegmatite), Galiléia, Doce valley, Minas Gerais, Brazil
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:Geoscience Museum, Institute of Geosciences, University of Sao Paulo, Brazil
Year of Discovery:1997
Geological Setting of type material:Secondary hydrothermal mineral in a pegmatite

Physical Properties of Coutinhoite

Lustre: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°
Maximum Birefringence:δ = 0.009

Chart 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:
Th
 
x
Ba
 
(1-2x)
(UO
 
2
)
 
2
Si
 
5
O
 
13
· (H
 
2
O)
 
1+y
(0 < x < 0.5 and 0 < y < (2+x))
Simplified for copy/paste:ThxBa(1-2x)(UO2)2Si5O13·(H2O)1+y (0 < x < 0.5 and 0 < y < (2+x))
All elements listed in formula:Ba, H, O, Si, Th, U

Relationship of Coutinhoite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
9.AK.05Soddyite
(UO
 
2
)
 
2
SiO
 
4
· 2H
 
2
O
9.AK.10Cuprosklodowskite
Cu(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 6H
 
2
O
9.AK.10Oursinite
(Co,Mg)(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 6H
 
2
O
9.AK.10Sklodowskite
Mg(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 5H
 
2
O
9.AK.15Boltwoodite
(K,Na)(UO
 
2
)[HSiO
 
4
] · 0.5H
 
2
O
9.AK.15Kasolite
Pb(UO
 
2
)[SiO
 
4
] · H
 
2
O
9.AK.15Natroboltwoodite
(H
 
3
O)(Na,K)UO
 
2
SiO
 
4
· H
 
2
O
9.AK.15β-Uranophane
Ca(UO
 
2
)
 
2
(HSiO
 
4
)
 
2
· 5H
 
2
O
9.AK.15Uranophane
Ca(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
· 5H
 
2
O
9.AK.15Beta-Uranophane
9.AK.20Swamboite
UH
 
6
(UO
 
2
)
 
6
(SiO
 
4
)
 
6
· 30H
 
2
O
9.AK.25Haiweeite
Ca(UO
 
2
)
 
2
[Si
 
5
O
 
12
(OH)
 
2
] · 6H
 
2
O
9.AK.25Metahaiweeite
Ca(UO
 
2
)
 
2
Si
 
6
O
 
15
· nH
 
2
O
9.AK.25Ranquilite
9.AK.30Weeksite
K
 
2
(UO
 
2
)
 
2
(Si
 
5
O
 
13
) · 4H
 
2
O
9.AK.35Ursilite
(Mg,Ca)
 
4
(UO
 
2
)
 
4
(Si
 
2
O
 
5
)
 
5.5
(OH)
 
5
· 13H
 
2
O
9.AK.35Magnioursilite
Mg
 
4
(UO
 
2
)
 
4
(Si
 
2
O
 
5
)
 
5
(OH)
 
6
· 20H
 
2
O
9.AK.35Calcioursilite
Ca
 
4
(UO
 
2
)
 
4
(Si
 
2
O
 
5
)
 
5
(OH)
 
6
· 15H
 
2
O
9.AK.40Uranosilite
UO
 
3
· 7SiO
 
2

Other Names for Coutinhoite

Synonyms:
IMA2003-025
Other Languages:

Other Information

Fluorescence in UV light:none
Health Warning: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

Search Engines:
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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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  • Localities for Coutinhoite

    The 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. ? 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.
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