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Marécottite

Big Photo

La Creusa U prospect (La Creusaz U prospect), Les Marécottes, Le Trient Valley, Wallis (Valais), Switzerland
© Knut Eldjarn

Show Marécottite Photos (4)
Formula:
(H
 
3
O)
 
8
Mg
 
3
(UO
 
2
)
 
4
[O
 
3
|OH|(SO
 
4
)
 
2
]
 
2
 · 10H
 
2
O
System:TriclinicColour:yellow-orange
Hardness:3
Name:For the village of Les Marécottes, whose church is 1100 meters from the type locality.
This page provides mineralogical data about Marécottite.

Classification of Marécottite

IMA status:Approved 2001
Strunz 8th edition ID:6/D.21-30
Nickel-Strunz 10th (pending) edition ID:7.EC.15

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
E : Uranyl sulfates
C : With medium-sized and large cations
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Type Occurrence of Marécottite

Type Locality:La Creusa U prospect (La Creusaz U prospect), Les Marécottes, Le Trient Valley, Wallis (Valais), Switzerland
General Appearance of Type Material:diamond shaped platelets to 500 µm
Place of Conservation of Type Material:Musée Géologique Cantonal at Lausanne, Switzerland
Geological Setting of type material:Alteration products of uraninite

Occurrences of Marécottite

Geological Setting:Weathered uranium deposits

Physical Properties of Marécottite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:yellow-orange
Streak:colorless
Hardness (Mohs):3
Tenacity:Very brittle
Cleavage:Perfect
(011)
Density (measured):4.03 g/cm3
Density (calculated):3.83 g/cm3

Crystallography of Marécottite

Crystal System:Triclinic
Class (H-M):1 - Pinacoidal
Space Group:P1
Cell Parameters:a = 10.815Å, b = 11.249Å, c = 13.852Å
α = 66.224°, β = 72.412°, γ = 69.995°
Ratio:a:b:c = 0.961 : 1 : 1.231
Unit Cell Volume:V 1422.1 ų
Twinning:Common, perpendicular to (011)

Optical Data of Marécottite

Type:Biaxial
RI values: n = 1.735 - 1.75
Maximum Birefringence:δ = 0.000

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Pleochroism:Visible
Comments:Pale yellow to orange yellow

Chemical Properties of Marécottite

Formula:
(H
 
3
O)
 
8
Mg
 
3
(UO
 
2
)
 
4
[O
 
3
|OH|(SO
 
4
)
 
2
]
 
2
 · 10H
 
2
O
All elements listed in formula:H, Mg, O, S, U

Relationship of Marécottite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
7.EC.05Cobaltzippeite
Co
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
·16H
 
2
O
7.EC.05Magnesiozippeite
Mg(UO
 
2
)
 
2
(SO
 
4
)(OH)
 
4
·1.5H
 
2
O
7.EC.05Nickelzippeite
Ni
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
·16H
 
2
O
7.EC.05Natrozippeite
Na
 
4
(UO
 
2
)
 
6
[(OH)
 
10
|(SO
 
4
)
 
3
] · 4H
 
2
O
7.EC.05Zinczippeite
Zn
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
·16H
 
2
O
7.EC.05Zippeite
K
 
4
(UO
 
2
)
 
6
[(OH)
 
10
|(SO
 
4
)
 
3
] · 4H
 
2
O
7.EC.10Rabejacite
Ca(UO
 
2
)
 
4
(SO
 
4
)
 
2
(OH)
 
6
 · 6H
 
2
O
7.EC.15IMA2009-008
Y
 
2
[(UO
 
2
)
 
8
O
 
6
(SO
 
4
)
 
4
(OH)
 
2
]·26H
 
2
O
7.EC.20Pseudojohannite
Cu
 
6.5
(UO
 
2
)
 
8
[O
 
8
|(OH)
 
5
|(SO
 
4
)
 
4
] · 25H
 
2
O

Other Names for Marécottite

Synonyms:
IMA2001-056Pseudo-Mg-Zippeite
Other Languages:
Russian:Марекоттит

Other Information

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 Marécottite

Reference List:Brugger, J., Burns, P., Meisser, N. (2003) Contribution to the mineralogy of acid drainage of uranium minerals: marécottite and the zippeite group. American Mineralogist: 88: 676-685.

Burns, P.C. (2005) U 6+ minerals and inorganic compounds: insights into an expanded structural hierarchy of crystal structures. Canadian Mineralogist: 43: 1839-1894.

Internet Links for Marécottite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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    Localities for Marécottite

    Hide Locality List
    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.
    Czech Republic
     
    • Bohemia (Böhmen; Boehmen)
      • Karlovy Vary Region
        • Krušné Hory Mts (Erzgebirge)
          • Ostrov
    		Am Min 88:4 pp 676-685
    • Moravia (Mähren; Maehren)
      • Vysočina Region
        • Rožná deposit
    		Petr Pauliš, Stanislav Kopecký, Pavel Černý: Uranové minerály České republiky a jejich lokality 2007
    Switzerland
     
    • Wallis (Valais)
      • Le Trient Valley
        • Les Marécottes
    		Am Min 88:4 pp 676-685
    USA
     
    • Utah
      • Emery Co.
        • San Rafael District (San Rafael Swell)
    		Am Min 88:4 pp 676-685
      • San Juan Co.
        • White Canyon District
          • White Canyon
    		Collected by Pat Haynes and analysis presumably done by Pat Haynes in order to describe this species from this locality.
    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: 12th Oct 2009 18:55:09