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Coutinhoite

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Urucum mine (Tim mine; Córrego do Urucum pegmatite), Galiléia, Doce valley, Minas Gerais, Southeast Region, Brazil
© Bruno Gioia

Show Coutinhoite Photos (4)
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, Southeast Region, 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))
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.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
]·4.5H
 
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
 
2
O
 
5
)
 
3
·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

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    Localities for Coutinhoite

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    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
     
    • Southeast Region
      • Minas Gerais
        • Doce valley
          • Galiléia
    		American Mineralogist (2004): 89(5-6): 721-724.
    Mineral and/or Locality
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    Copyright © Jolyon Ralph and Ida Chau 1993-2009. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them.Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. If you would like to add information to improve the quality of our database, then click here to register. Current server date and time: 18th Nov 2009 07:24:26