Oppenheimerite
Very rare uranium mineral
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Oppenheimerite is a very rare uranium mineral with the formula Na2(UO2)(SO4)2•3H2O.[2][3] Chemically related minerals include fermiite, natrozippeite, plášilite, belakovskiite and meisserite.[4][5][6][7][8] Most of these uranyl sulfate minerals were originally found in the Blue Lizard mine, San Juan County, Utah, US.[9] The mineral is named after American Theoretical physicist J. Robert Oppenheimer.[3]
| Oppenheimerite | |
|---|---|
| General | |
| Category | Sulfate mineral |
| Formula | Na2(UO2)(SO4)2•3H2O |
| IMA symbol | Ohm[1] |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Unit cell | a = 7.96, b = 8.20, c = 9.81 [Å]; α = 65.97° β = 70.28°, γ = 91.46° (approximated), Z = 2 |
| Identification | |
| Color | Pale greenish-yellow |
| Crystal habit | prismatic |
| Cleavage | {110}, {011} and {101}, good |
| Fracture | Irregular |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent |
| Density | 3.36 (calculated) (approximated) |
| Optical properties | Biaxal (+) |
| Refractive index | nα=1.54, nβ=1.63, nγ=1.59 (approximated) |
| Pleochroism | Very pale greenish-yellow (X), pale greenish-yellow (Y), greenish-yellow (Z) |
| 2V angle | 72o (measured) |
| Ultraviolet fluorescence | Greenish-white |
| Other characteristics |  Radioactive |
| References | [2][3] |
Association and origin
Oppenheimerite is associated with other sulfate minerals: fermiite, bluelizardite, wetherillite, blödite, chalcanthite, epsomite, gypsum, hexahydrite, kröhnkite, manganoblödite, sideronatrite, and tamarugite.[2]
Crystal structure
The crystal structure of oppenheimerite is of a new type. It contains chains of the (UO2)(SO4)2(H2O) composition, connected with two types of sodium polyhedra.[2]