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Posnjakite

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Formula:
Cu
 
4
(SO
 
4
)(OH)
 
6
· H
 
2
O
System:MonoclinicColour:Sky-blue to dark-blue, ...
Lustre:VitreousHardness:2 - 3
Name:Named in 1967 for Eugene Waldemar Posnjak (1888-1949), U.S. geochemist at the Geophysical Laboratory, Washington, U.S.A., who investigated the system CuO-SO3-H2O.


A copper sulphate hydrate that generally forms at low temperatures (Yoder et al., 2007). Compare also wroewolfeite.

Certain habits are easily confused with the closely related langite.

Classification of Posnjakite

IMA status:Approved
Strunz 8th edition ID:6/D.03-10
Nickel-Strunz 10th (pending) edition ID:7.DD.10

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
D : Sulfates (selenates, etc.) with additional anions, with H2O
D : With only medium-sized cations; sheets of edge-sharing octahedra
Dana 8th edition ID:31.4.1.1

31 : HYDRATED SULFATES CONTAINING HYDROXYL OR HALOGEN
4 : (AB)4(XO4)Zq·xH2O
Hey's CIM Ref.:25.2.8

25 : Sulphates
2 : Sulphates of Cu and Ag
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Type Occurrence of Posnjakite

Type Locality:Nura-Taldy W deposit, Karagandy Province (Qaragandy Oblysy; Karaganda Oblast'), Kazakhstan
Year of Discovery:1967

Physical Properties of Posnjakite

Lustre:Vitreous
Colour:Sky-blue to dark-blue, may be slightly greenish-blue.
Streak:Pale-blue.
Hardness (Mohs):2 - 3

Crystallography of Posnjakite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Pm {P1 1m} {Pm} {P1m1}
Cell Parameters:a = 10.578(5) Å, b = 6.345(3) Å, c = 7.863(3) Å
β = 117.98(5)°
Ratio:a:b:c = 1.667 : 1 : 1.239
Unit Cell Volume:V 466.06 ų
Z:2
Comment:Reduced cell is 6.345, 7.863, 9.781 A, 107.247, 90, 89.999°.
X-Ray Powder Diffraction:
d-spacingIntensity
7.0 (10)
3.46 (8)
2.70 (7)
2.61 (7)
2.41 (7)
2.015 (7)
1.538 (7)

Optical Data of Posnjakite

Type:Biaxial (-)
RI values: nα = 1.625 nβ = 1.680 nγ = 1.706
2V:Measured: 57° , Calculated: 66°
Maximum Birefringence:δ = 0.081

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

Chemical Properties of Posnjakite

Formula:
Cu
 
4
(SO
 
4
)(OH)
 
6
· H
 
2
O
Simplified for copy/paste:Cu4(SO4)(OH)6·H2O
Essential elements:Cu, H, O, S
All elements listed in formula:Cu, H, O, S

Relationship of Posnjakite to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
7.DD.05Felsőbányaite
Al
 
4
(SO
 
4
)(OH)
 
10
· 4H
 
2
O
7.DD.10Langite
Cu
 
4
(SO
 
4
)(OH)
 
6
· 2H
 
2
O
7.DD.10Wroewolfeite
Cu
 
4
(SO
 
4
)(OH)
 
6
· 2H
 
2
O
7.DD.15Spangolite
Cu
 
6
Al(SO
 
4
)(OH)
 
12
Cl · 3H
 
2
O
7.DD.20Ktenasite
Zn(Cu,Zn)
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 6H
 
2
O
7.DD.25Christelite
Cu
 
2
Zn
 
3
(SO
 
4
)
 
2
(OH)
 
6
· 4H
 
2
O
7.DD.30Campigliaite
Mn
2+
 
Cu
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 4H
 
2
O
7.DD.30Devilline
CaCu
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 3H
 
2
O
7.DD.30Orthoserpierite
Ca(Cu,Zn)
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 3H
 
2
O
7.DD.30Serpierite
Ca(Cu,Zn)
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 3H
 
2
O
7.DD.30Niedermayrite
CdCu
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 4H
 
2
O
7.DD.30Edwardsite
Cu
 
3
Cd
 
2
(SO
 
4
)
 
2
(OH)
 
6
·4H
 
2
O
7.DD.35Carrboydite
[(Ni
 
1-x
Al
 
x
)(OH)
 
2
][SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Glaucocerinite
(Zn
 
1-x
Al
 
x
)(OH)
 
2
(SO
 
4
)
 
x/2
· nH
 
2
O
7.DD.35Honessite
(Ni
 
1-x
Fe
3+
x
)(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Hydrohonessite
(Ni
 
1-x
Fe
3+
x
)(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Motukoreaite
Mg
 
6
Al
 
3
(OH)
 
18
[Na(H
 
2
O)
 
6
][SO
 
4
]
 
2
· 6H
 
2
O
7.DD.35Mountkeithite
[(Mg
 
1-x
Fe
3+
x
)(OH)
 
2
][SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Shigaite
Mn
 
6
Al
 
3
(OH)
 
18
[Na(H
 
2
O)
 
6
][SO
 
4
]
 
2
· 6H
 
2
O
7.DD.35Wermlandite
Mg
 
7
Al
 
2
(OH)
 
18
[Ca(H
 
2
O)
 
6
][SO
 
4
]
 
2
· 6H
 
2
O
7.DD.35Woodwardite
Cu
 
1-x
Al
 
x
(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Zincaluminite
Zn
 
6
Al
 
6
(SO
 
4
)
 
2
(OH)
 
16
· 5H
 
2
O
7.DD.35Hydrowoodwardite
(Cu
 
1-x
Al
 
x
)(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Zincowoodwardite
Zn
 
1-x
Al
 
x
(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
7.DD.35Natroglaucocerinite
Na
 
x
Zn
 
8-y
Al
 
y
(SO
 
4
)
 
(x+y)/2
(OH)
 
16
· 6H
 
2
O
7.DD.35Nikischerite
Fe
2+
6
Al
 
3
(OH)
 
18
[Na(H
 
2
O)
 
6
][SO
 
4
]
 
2
· 6H
 
2
O
7.DD.40Lawsonbauerite
(Mn
2+
 
,Mg)
 
9
Zn
 
4
(SO
 
4
)
 
2
(OH)
 
22
· 8H
 
2
O
7.DD.40Torreyite
(Mg,Mn
2+
 
)
 
7
 
2
Mn
2+
2
Zn
 
4
(SO
 
4
)
 
2
(OH)
 
22
· 8H
 
2
O
7.DD.45Mooreite
Mg
 
9
 
2
Mn
 
2
Zn
 
4
(SO
 
4
)
 
2
(OH)
 
26
· 8H
 
2
O
7.DD.50Namuwite
(Zn,Cu)
 
4
(SO
 
4
)(OH)
 
6
· 4H
 
2
O
7.DD.55Bechererite
(Zn,Cu)
 
6
Zn
 
2
(SO
 
4
,HSiO
 
4
)
 
2
(OH)
 
12
7.DD.60Ramsbeckite
(Cu,Zn)
 
15
(SO
 
4
)
 
4
(OH)
 
22
· 6H
 
2
O
7.DD.65Vonbezingite
Ca
 
6
Cu
 
3
(SO
 
4
)
 
3
(OH)
 
12
· 2H
 
2
O
7.DD.70Redgillite
Cu
 
6
(SO
 
4
)(OH)
 
10
· H
 
2
O
7.DD.75Chalcoalumite
CuAl
 
4
(SO
 
4
)(OH)
 
12
· 3H
 
2
O
7.DD.75Nickelalumite
(Ni,Cu)Al
 
4
(SO
 
4
,(NO
 
3
)
 
2
)(OH)
 
12
· 3H
 
2
O
7.DD.75Kyrgyzstanite
ZnAl
 
4
(SO
 
4
)(OH)
 
12
·3H
 
2
O
7.DD.80Guarinoite
(Zn,Co,Ni)
 
6
(SO
 
4
)(OH,Cl)
 
10
· 5H
 
2
O
7.DD.80Schulenbergite
(Cu,Zn)
 
7
(SO
 
4
,CO
 
3
)
 
2
(OH)
 
10
· 3H
 
2
O
7.DD.80Thérèsemagnanite
(Co,Zn,Ni)
 
6
(SO
 
4
)(OH,Cl)
 
10
· 8H
 
2
O
7.DD.80UM1992-30-SO:CCuHZn
(Zn,Cu)
 
7
(SO
 
4
,CO
 
3
)
 
2
(OH)
 
10
· 3H
 
2
O
7.DD.85Montetrisaite
Cu
 
6
(SO
 
4
)(OH)
 
10
· 2H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
25.2.1Chalcocyanite
CuSO
 
4
25.2.2Bonattite
CuSO
 
4
· 3H
 
2
O
25.2.3Chalcanthite
CuSO
 
4
· 5H
 
2
O
25.2.4Boothite
CuSO
 
4
· 7H
 
2
O
25.2.5Dolerophanite
Cu
 
2
(SO
 
4
)O
25.2.6Antlerite
Cu
 
3
(SO
 
4
)(OH)
 
4
25.2.7Brochantite
Cu
 
4
(SO
 
4
)(OH)
 
6
25.2.9Langite
Cu
 
4
(SO
 
4
)(OH)
 
6
· 2H
 
2
O
25.2.10Wroewolfeite
Cu
 
4
(SO
 
4
)(OH)
 
6
· 2H
 
2
O
25.2.11Kröhnkite
Na
 
2
Cu(SO
 
4
)
 
2
· 2H
 
2
O
25.2.12Natrochalcite
NaCu
 
2
(SO
 
4
)
 
2
(OH) · 2H
 
2
O
25.2.13Piypite
K
 
2
Cu
 
2
(SO
 
4
)
 
2
O
25.2.14Fedotovite
K
 
2
Cu
 
3
(SO
 
4
)
 
3
O
25.2.15Cyanochroite
K
 
2
Cu(SO
 
4
)
 
2
· 6H
 
2
O
25.2.16Euchlorine
KNaCu
 
3
(SO
 
4
)
 
3
O
25.2.17Devilline
CaCu
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 3H
 
2
O
25.2.18Leightonite
K
 
2
Ca
 
2
Cu(SO
 
4
)
 
4
· 2H
 
2
O
25.2.19Chalcoalumite
CuAl
 
4
(SO
 
4
)(OH)
 
12
· 3H
 
2
O
25.2.20Cyanotrichite
Cu
 
4
Al
 
2
(SO
 
4
)(OH)
 
12
· 2H
 
2
O
25.2.21Woodwardite
Cu
 
1-x
Al
 
x
(OH)
 
2
[SO
 
4
]
 
x/2
· nH
 
2
O
25.2.22Campigliaite
Mn
2+
 
Cu
 
4
(SO
 
4
)
 
2
(OH)
 
6
· 4H
 
2
O
25.2.23Guildite
CuFe
3+
 
(SO
 
4
)
 
2
(OH) · 4H
 
2
O
25.2.24Ransomite
CuFe
 
2
(SO
 
4
)
 
4
· 6H
 
2
O
25.2.26Klyuchevskite
K
 
3
Cu
 
3
(Fe
3+
 
,Al)(SO
 
4
)
 
4
O
 
2
25.2.27Poitevinite
(Cu,Fe,Zn)SO
 
4
· H
 
2
O
25.2.28Argentojarosite
AgFe
3+
3
(SO
 
4
)
 
2
(OH)
 
6

Other Names for Posnjakite

Synonyms:
IMA1967-001
Other Languages:
German:Posnjakit
Russian:Познякит
Simplified Chinese:一水蓝铜矾
一水兰铜矾
Spanish:Posnjakita
Traditional Chinese:一水藍銅礬
一水蘭銅礬

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 Posnjakite

Reference List:

- +
American Mineralogist (1967): 52: 1582-1583.

Zapiski Vserossiyskogo Mineralogicheskogo Obshchestva: 96: 58-62.

Mellini, M. & Merlino, S. (1979): Zeitschrift für Kristallographie: 149: 249-257.

American Mineralogist (1983): 68: 1251.

Yoder, C. H., Agee, T. M., Ginion, K. E., Hofmann, A. E., Ewanichak, J. E., Schaeffer, C. D., Jr., Carroll, M. J., Schaeffer, R. W. & McCaffrey, P. F. (2007): The relative stabilities of the copper hydroxyl sulphates. Mineralogical Magazine 71, 571-577.

Internet Links for Posnjakite

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  • Localities for Posnjakite

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