Plášilite

Plášilite
General
Category Sulfate mineral
Formula
(repeating unit)
Na(UO2)(SO4)(OH)•2H2O
Crystal system Monoclinic, P21/c
Unit cell a=8.71, b=13.84, c=7.05 [Å], β=112.13o (approximated)
Identification
Color Greenish yellow
Crystal habit prismatic
Crystal symmetry Monoclinic - Prismatic (2/m)
Cleavage {010} and {001}, perfect
Tenacity Brittle
Mohs scale hardness 2-3
Luster Vitreous
Streak White
Diaphaneity Transparent
Density 3.73 (calculated) (approximated)
Optical properties Biaxal (+)
Refractive index nα=1.56, nβ=1.58, nγ=1.61 (approximated)
Pleochroism ~Colourless (X), very pale yellow (Y), pale yellow (Z)
2V angle 88o (measured)
Ultraviolet fluorescence Bluish-white
Other characteristics Radioactive
References [1][2]

Plášilite is a very rare uranium mineral with the formula Na2(UO2)(SO4)2•3H2O.[1][2] Chemically related minerals include natrozippeite, belakovskiite, meisserite, fermiite and oppenheimerite.[3][4][5][6][7] Most of these uranyl sulphate minerals were originally found in the Blue Lizard mine, San Juan County, Utah, US.[8] The mineral is named after Czech crystallographer Jakub Plášil.[2]

Association and origin

Plášilite is associated with other sulfate minerals: natrozippeite, johannite, blödite, brochantite, chalcanthite, gypsum, hexahydrite, manganoblödite, and tamarugite. Non-sulfate coexisting minerals include atacamite, calcite, dickite and gerhardtite. Plášilite is secondary in origin, being the product of weathering of the primary uranium mineral, uraninite.[1]

Crystal structure

The crystal structure of plášilite is of a new type. Its building blocks are:[1]

The sodium-bearing polyhedra link the uranyl-sulfate sheets. It terms of sheet geometry, crystal structure of plášilite is similar to that of deliensite.[1]

References

  1. 1 2 3 4 5 Kampf, A.R., Kasatkin, A.V., Čejka, J., and Marty, J., 2015. Plášilite, Na(UO2)(SO4)(OH)·2H2O, a new uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA. Journal of Geosciences 60, 1-10
  2. 1 2 3 "Plášilite: Plášilite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  3. "Natrozippeite: Natrozippeite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  4. "Belakovskiite: Belakovskiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  5. "Meisserite: Meisserite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  6. "Fermiite: Fermiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  7. "Oppenheimerite: Oppenheimerite mineral information and data". Mindat.org. Retrieved 2016-03-10.
  8. "Blue Lizard Mine, Chocolate Drop, Red Canyon, White Canyon District, San Juan Co., Utah, USA - Mindat.org". Mindat.org. Retrieved 2016-03-10.


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