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Geminite

Big Photo

Salsigne mine, Salsigne, Mas-Cabardès, Carcassonne, Aude, Languedoc-Roussillon, France
© Elmar Lackner

Show Geminite Photos (10)
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
H
 
2
(PO
 
4
)
 
4
·4H
 
2
O
8.CB.10Irhtemite
Ca
 
4
Mg[(HAsO
 
4
)
 
2
|(AsO
 
4
)
 
2
] · 4H
 
2
O
8.CB.10Sainfeldite
Ca
 
5
H
 
2
(AsO
 
4
)
 
4
·4H
 
2
O
8.CB.10Villyaellenite
(Mn,Ca,Zn)
 
5
(AsO
 
4
)
 
2
[AsO
 
3
(OH)]
 
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
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
German names:
Geminit
Russian names:
Геминит
Spanish names:
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.

Articles/Blogs about Geminite

Internet Links for Geminite

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    Localities for Geminite

    (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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