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Sejkoraite-(Y)

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About Sejkoraite-(Y)Hide

Jirí Sejkora
Formula:
Y2(UO2)8(SO4)4O6(OH)2 · 26H2O
Colour:
Yellow-orange to orange
Lustre:
Vitreous
Hardness:
2
Specific Gravity:
4.04 (Calculated)
Crystal System:
Triclinic
Member of:
Name:
In honour of Dr. Jirí Sejkora, a Czech mineralogist of the National Museum in Prague, and specialist on secondary uranium minerals. Dr. Sejkora has described a large number of new species.
Zippeite Group. Chemically very similar to alwilkinsite-(Y), the second known yttrium uranyl sulphate mineral; these two minerals and bijvoetite-(Y) and kamotoite-(Y) constitute the whole small group of natural Y-U salts.

Structure seems to be related to that of Marécottite.


Classification of Sejkoraite-(Y)Hide

Approved
Approval Year:
2009
7.EC.15

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

Physical Properties of Sejkoraite-(Y)Hide

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

Optical Data of Sejkoraite-(Y)Hide

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

Formula:
Y2(UO2)8(SO4)4O6(OH)2 · 26H2O
IMA Formula:
Y2[(UO2)8O6(SO4)4(OH)2] · 26H2O

Crystallography of Sejkoraite-(Y)Hide

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 V:
2,767.15 ų (Calculated from Unit Cell)
Z:
2

X-Ray Powder DiffractionHide

Powder Diffraction Data:
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)

Type Occurrence of Sejkoraite-(Y)Hide

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:

Synonyms of Sejkoraite-(Y)Hide

Relationship of Sejkoraite-(Y) to other SpeciesHide

Member of:
Other Members of this group:
Ammoniozippeite(NH4)2[(UO2)2(SO4)O2]·H2OOrth.
CobaltzippeiteCo(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
MagnesiozippeiteMg(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
NatrozippeiteNa5(UO2)8(SO4)4O5(OH)3 · 12H2OMon. 2/m : P21/m
NickelzippeiteNi2(UO2)6(SO4)3(OH)10 · 16H2O Mon.
PlavnoiteK0.8Mn0.6[(UO2)2O2(SO4)]·3.5H2OMon. 2/m : B2/m
PseudojohanniteCu3(OH)2[(UO2)4(SO4)2]· 12H2OTric.
ZinczippeiteZn(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
ZippeiteK3(UO2)4(SO4)2O3(OH) · 3H2OMon. 2 : B2

Common AssociatesHide

Associated Minerals Based on Photo Data:
Gypsum1 photo of Sejkoraite-(Y) associated with Gypsum on mindat.org.
Pseudojohannite1 photo of Sejkoraite-(Y) associated with Pseudojohannite on mindat.org.
Cuprosklodowskite1 photo of Sejkoraite-(Y) associated with Cuprosklodowskite on mindat.org.
Rabejacite1 photo of Sejkoraite-(Y) associated with Rabejacite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

7.EC.AdolfpateraiteK(UO2)(SO4)(OH)(H2O)Mon. 2/m : P21/b
7.EC.05CobaltzippeiteCo(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
7.EC.05MagnesiozippeiteMg(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
7.EC.05NickelzippeiteNi2(UO2)6(SO4)3(OH)10 · 16H2O Mon.
7.EC.05NatrozippeiteNa5(UO2)8(SO4)4O5(OH)3 · 12H2OMon. 2/m : P21/m
7.EC.05ZinczippeiteZn(UO2)2(SO4)O2 · 3.5H2OMon. 2/m : B2/m
7.EC.05ZippeiteK3(UO2)4(SO4)2O3(OH) · 3H2OMon. 2 : B2
7.EC.10RabejaciteCa(UO2)4(SO4)2(OH)6 · 6H2OOrth.
7.EC.15MarécottiteMg3(UO2)8(SO4)4O6(OH)2 · 28H2OTric. 1 : P1
7.EC.20PseudojohanniteCu3(OH)2[(UO2)4(SO4)2]· 12H2OTric.

Fluorescence of Sejkoraite-(Y)Hide

Other InformationHide

Health Risks:
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)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
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)Hide

Localities for Sejkoraite-(Y)Hide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Czech Republic
 
  • Karlovy Vary Region
    • Krušné Hory Mts (Erzgebirge)
      • Jáchymov District (St Joachimsthal)
        • 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. ; Jakub Plášil, Jiří Sejkora, Radek Škoda, Pavel Škácha (2014): The recent weathering of uraninite from the Červená vein, Jáchymov (Czech Republic): a fingerprint of the primary mineralization geochemistry onto the alteration association. Journal of Geosciences, 59, 223-253.
Mineral and/or Locality  
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