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Sejkoraite-(Y)

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Rovnost Mine (Werner Mine), Jáchymov (St Joachimsthal), Jáchymov (St Joachimsthal) District, Krušné Hory Mts (Erzgebirge), Karlovy Vary Region, Bohemia (Böhmen; Boehmen), Czech Republic




Formula:
Y
 
2
(UO
 
2
)
 
8
(SO
 
4
)
 
4
O
 
6
(OH)
 
2
 · 26H
 
2
O
System:TriclinicColour:Yellow-orange to orange
Hardness:2
Member of:Zippeite Group
Name:In honour of Dr. Jirí Sejkora, a Czech mineralogist of the National Museum in Prague, and specialist on seconary uranium minerals. Dr. Sejkora has described a large number of new species.


Zippeite Group.
Structure seems to be related to that of marécottite.

Classification of Sejkoraite-(Y)

IMA status:Approved 2009
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 Sejkoraite-(Y)

Type Locality:Červena vein, Rovnost Mine (Werner Mine), Jáchymov (St Joachimsthal), Jáchymov (St Joachimsthal) District, Krušné Hory Mts (Erzgebirge), Karlovy Vary Region, Bohemia (Böhmen; Boehmen), Czech Republic
General Appearance of Type Material:Crystalline aggregates consisting of yellow-orange to orange crystals, rarely up to 1 mm in diameter.
Place of Conservation of Type Material:National Museum in Prague
Associated Minerals at type locality:
ZippeiteUranopiliteUraniniteTennantiteRabejacite
PseudojohanniteGypsumChalcopyrite

Physical Properties of Sejkoraite-(Y)

Lustre:Vitreous
Colour:Yellow-orange to orange
Streak:Pale yellow to yellow
Hardness (Mohs):2
Tenacity:Brittle
Cleavage:Perfect
{100}
Fracture:Irregular/Uneven
Density (calculated):4.04 g/cm3

Crystallography of Sejkoraite-(Y)

Crystal System:Triclinic
Class (H-M):1 - Pinacoidal
Space Group:P1
Cell Parameters:a = 13.949(1) Å, b = 14.329(1) Å, c = 15.104(1) Å
α = 107.440(4)°, β = 95.751(5)°, γ = 102.515(4)°
Ratio:a:b:c = 0.973 : 1 : 1.054
Unit Cell Volume:V 2,767.15 ų (Calculated from Unit Cell)
Z:2
X-Ray Powder Diffraction:
d-spacingIntensity
14.12 (5)
9.28 (100)
4.64 (41)
3.451 (8)
3.385 (7)
3.293 (13)
3.094 (8)
3.059 (7)

Optical Data of Sejkoraite-(Y)

Type:Biaxial (-)
RI values: nα = 1.620(2) nβ = 1.662(3) nγ = 1.730(1)
2V:Calculated: 79°
Maximum Birefringence:δ = 0.110

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Pleochroism:Not Visible
Comments:Refractive indices are approximate (alpha prime instead of alpha, etc.)

Chemical Properties of Sejkoraite-(Y)

Formula:
Y
 
2
(UO
 
2
)
 
8
(SO
 
4
)
 
4
O
 
6
(OH)
 
2
 · 26H
 
2
O
Essential elements:H, O, S, U, Y
All elements listed in formula:H, O, S, U, Y

Relationship of Sejkoraite-(Y) to other Species

Member of:Zippeite Group
Other Members of Group:

- +
Cobaltzippeite
Co
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
 · 16H
 
2
O
Magnesiozippeite
Mg(UO
 
2
)
 
2
(SO
 
4
)(OH)
 
4
 · 1.5H
 
2
O
Natrozippeite
Na
 
4
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
 · 4H
 
2
O
Nickelzippeite
Ni
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
 · 16H
 
2
O
Pseudojohannite
Cu
 
6.5
(UO
 
2
)
 
8
(SO
 
4
)
 
4
O
 
8
(OH)
 
5
 · 25H
 
2
O
Zinczippeite
Zn
 
2
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
 · 16H
 
2
O
Zippeite
K
 
4
(UO
 
2
)
 
6
(SO
 
4
)
 
3
(OH)
 
10
 · 4H
 
2
O
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
(SO
 
4
)
 
3
(OH)
 
10
 · 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
(SO
 
4
)
 
3
(OH)
 
10
 · 4H
 
2
O
7.EC.10Rabejacite
Ca(UO
 
2
)
 
4
(SO
 
4
)
 
2
(OH)
 
6
 · 6H
 
2
O
7.EC.15Marécottite
Mg
 
3
(UO
 
2
)
 
8
(SO
 
4
)
 
4
O
 
6
(OH)
 
2
 · 28H
 
2
O
7.EC.20Pseudojohannite
Cu
 
6.5
(UO
 
2
)
 
8
(SO
 
4
)
 
4
O
 
8
(OH)
 
5
 · 25H
 
2
O

Other Names for Sejkoraite-(Y)

Synonyms:
IMA2009-008
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 Sejkoraite-(Y)

Reference List:

- +
Plášil, J., Dušek, M., Novák, M., Čejka, J., Císařová, I., Škoda, R. (2011): Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement. American Mineralogist, 96, 983-991.

Internet Links for Sejkoraite-(Y)

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    • Localities for Sejkoraite-(Y)

    Hide Locality List
    (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)
          • Jáchymov (St Joachimsthal) District
            • Jáchymov (St Joachimsthal)
    		Tvrdý, J. & Plášil, J. (2010): Jáchymov - Reiche Erzlagerstätte und Radonbad im böhmischen Westerzgebirge. Aufschluss 61, 277-292.
    Tvrdý, J. & Plášil, J. (2010): Jáchymov - Reiche Erzlagerstätte und Radonbad im böhmischen Westerzgebirge. Aufschluss 61, 277-292.
    Plášil, J., Dušek, M., Novák, M., Čejka, J., Císařová, I., Škoda, R. (2011): Sejkoraite-(Y), a new member of the zippeite group containing trivalent cations from Jáchymov (St. Joachimsthal), Czech Republic: Description and crystal structure refinement. American Mineralogist, 96, 983-991.
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