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]
- (UO2)2(SO4)2(OH)2 sheets, with a charge 2-, parallel to (010), of a phosphuranylite topology
- edge-sharing NaO2(H2O)4 polyhedra, parallel to [001]
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 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
- 1 2 3 "Plášilite: Plášilite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Natrozippeite: Natrozippeite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Belakovskiite: Belakovskiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Meisserite: Meisserite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Fermiite: Fermiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Oppenheimerite: Oppenheimerite mineral information and data". Mindat.org. Retrieved 2016-03-10.
- ↑ "Blue Lizard Mine, Chocolate Drop, Red Canyon, White Canyon District, San Juan Co., Utah, USA - Mindat.org". Mindat.org. Retrieved 2016-03-10.