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Geminite

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Shaft 371, Schlema-Hartenstein District, Erzgebirge, Saxony, Germany
© Thomas Witzke

Show Geminite Photos (11)
Formula:
Cu
 
2
[As
 
2
O
 
7
] · 3H
 
2
O
System:TriclinicHardness:3 - 3½
This page provides mineralogical data about Geminite.

Classification of Geminite

IMA status:Approved 1988
Strunz 8th edition ID:7/C.06-30
Nickel-Strunz 10th (pending) edition ID:8.CB.30

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
B : With only medium-sized cations, RO4:H2O = 1:1
Dana 8th edition ID:40.5.12.1

40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
5 : AXO4·xH2O
Hey's CIM Ref.:20.1.7

20 : Arsenates (also arsenates with phosphate, but without other anions)
1 : Arsenates of Cu
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Type Occurrence of Geminite

Type Locality:Cap Garonne Mine, Pradet, Var, Provence-Alpes-Côte d'Azur, France
Year of Discovery:1990

Physical Properties of Geminite

Hardness (Mohs):3 - 3½

Crystallography of Geminite

Crystal System:Triclinic
Cell Parameters:a = 6.63Å, b = 8.11Å, c = 15.73Å
α = 92.01°, β = 93.87°, γ = 95.02°
Ratio:a:b:c = 0.818 : 1 : 1.94
Unit Cell Volume:V 839.91 ų (Calculated from Unit Cell)

Optical Data of Geminite

Type:Biaxial (+)
RI values: nα = 1.656 nβ = 1.692 nγ = 1.770
2V:Measured: 75° , Calculated: 72°
Maximum Birefringence:δ = 0.114

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:weak

Chemical Properties of Geminite

Formula:
Cu
 
2
[As
 
2
O
 
7
] · 3H
 
2
O
Essential elements:As, Cu, H, O
All elements listed in formula:As, Cu, H, O

Relationship of Geminite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
8.CB.05Serrabrancaite
MnPO
 
4
·H
 
2
O
8.CB.10Hureaulite
(Mn,Fe)
 
5
(PO
 
3
OH)
 
2
(PO
 
4
)
 
2
·4H
 
2
O
8.CB.10Sainfeldite
Ca
 
5
(AsO
 
3
OH)
 
2
(AsO
 
4
)
 
2
·4H
 
2
O
8.CB.10Villyaellenite
(Mn,Ca,Zn)
 
5
(AsO
 
3
OH)
 
2
(AsO
 
4
)
 
2
·4H
 
2
O
8.CB.10UM1997-09-AsO:CaHMgZn
(Mg,Ca,Zn)
 
5
(AsO
 
4
)
 
2
[AsO
 
3
(OH)]
 
2
·4H
 
2
O
8.CB.10IMA2008-047
Cd
 
3
Zn
 
2
(AsO
 
3
OH)
 
2
(AsO
 
4
)
 
2
·4H
 
2
O
8.CB.10Miguelromeroite
Mn
 
5
(AsO
 
3
OH)
 
2
(AsO
 
4
)
 
2
·4H
 
2
O
8.CB.15Fluckite
CaMnH
 
2
(AsO
 
4
)
 
2
·2H
 
2
O
8.CB.15Krautite
MnHAsO
 
4
·H
 
2
O
8.CB.20Cobaltkoritnigite
(Co,Zn)[HAsO
 
4
] · H
 
2
O
8.CB.20Koritnigite
Zn[HAsO
 
4
] · H
 
2
O
8.CB.25Yvonite
Cu[HAsO
 
4
] · 2H
 
2
O
8.CB.35Schubnelite
Fe
 
2-x
V
 
2
O
 
4
(OH)
 
4
8.CB.40Radovanite
Cu
 
2
Fe
3+
 
[(As
3+
 
O
 
2
(OH)]
 
2
[As
5+
 
O
 
4
]·H
 
2
O
8.CB.45Kazakhstanite
Fe
 
5
V
 
3
V
 
12
O
 
39
(OH)
 
9
·9H
 
2
O
8.CB.50Kolovratite
(Zn,Ni,Cu)
 
2-5
Al
 
4-6
(Si,V
4+
 
,V
5+
 
)
 
4
(O,OH)
 
20
·7.5H
 
2
O
8.CB.55Irhtemite
Ca
 
4
Mg[(HAsO
 
4
)
 
2
|(AsO
 
4
)
 
2
] · 4H
 
2
O
8.CB.60Burgessite
Co
 
2
 (H
 
2
O)
 
4
[AsO
 
3
OH]
 
2
(H
 
2
O)}
Related Minerals - Hey's Index Grouping:

- +
20.1.1Lammerite
Cu
 
3
[AsO
 
4
]
 
2
20.1.2Olivenite
Cu
 
2
[OH|AsO
 
4
]
20.1.3Clinoclase
Cu
 
3
[(OH)
 
3
|AsO
 
4
]
20.1.4Cornwallite
Cu
 
5
[(OH)
 
2
|AsO
 
4
]
 
2
20.1.5Cornubite
Cu
 
5
[(OH)
 
2
|AsO
 
4
]
 
2
20.1.6Chlorotile (of Frenzel)
20.1.8Euchroite
Cu
 
2
[OH|AsO
 
4
] · 3H
 
2
O
20.1.9Strashimirite
Cu
 
8
[OH|AsO
 
4
]
 
4
 · 5H
 
2
O
20.1.10Arhbarite
Cu
 
2
Mg[(OH)
 
3
|AsO
 
4
]
20.1.11Lindackerite
CuCu
 
4
[HAsO
 
4
|AsO
 
4
]
 
2
 · 8-9H
 
2
O
20.1.12Conichalcite
CaCu[OH|AsO
 
4
]
20.1.13Liroconite
Cu
 
2
Al[(OH)
 
4
|AsO
 
4
] · 4H
 
2
O
20.1.14Ceruleite
Cu
 
2
Al
 
7
[(OH)
 
13
|(AsO
 
4
)
 
4
] · 11.5H
 
2
O
20.1.15Chenevixite
Cu
 
2
Fe
3+
2
[(OH)
 
2
|AsO
 
4
]
 
2
20.1.16Arthurite
CuFe
3+
2
[(OH,O)|(AsO
 
4
,PO
 
4
,SO
 
4
)]
 
2
 · 4H
 
2
O

Other Names for Geminite

Synonyms:
IMA1988-045
Other Languages:
German:Geminit
Russian:Геминит
Spanish:Geminita

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 Geminite

Reference List:New Minerals (1997), New Minerals 1990-1994.

Schweizerische mineralogische und petrographische Mitteilungen: 70: 309-314.

Canadian Mineralogist: 33: 1111-1118.

Internet Links for Geminite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
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  • Geminite details from Handbook of Mineralogy (PDF)
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    Localities for Geminite

    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
            • Jáchymov (St Joachimsthal)
    		Lapis 2002(7/8), 54
    Lapis 2002(7/8), 54
    France
     
    • Languedoc-Roussillon
      • Aude
        • Carcassonne
          • Mas-Cabardès
            • Salsigne
    		[AmMin 84:197]
    • Provence-Alpes-Côte d'Azur
      • Var
        • Pradet
    		Schweiz.Min.Petr.Mitt.(1990) 70, 309-314
    Germany
     
    • Saxony
      • Erzgebirge
        • Schlema-Hartenstein District
    		Lapis 1994(10), 36-39
    Morocco
     
    • Souss-Massa-Draâ Region
      • Ouarzazate Province
        • Tazenakht
          • Bou Azzer District
            • Khder
    		Favreau, G. and Dietrich, J. E. (2006). Die Mineralien von Bou Azzer. Lapis 31(7/8), 27-68
    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: 7th Nov 2009 05:53:03