Oppenheimerite

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 (repeating unit)	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	72^o (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]

References

1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
2. Kampf, A.R., Plášil, J., Kasatkin, A.V., Marty, J., and Čejka, J., 2015. Fermiite, Na4(UO2)(SO4)3·3H2O and oppenheimerite, Na2(UO2)(SO4)2·3H2O, two new uranyl sulfate minerals from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine 79(5), 1123-1142
3. "Oppenheimerite: Oppenheimerite mineral information and data". Mindat.org. Retrieved 2016-03-10.
4. "Fermiite: Fermiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
5. "Natrozippeite: Natrozippeite mineral information and data". Mindat.org. Retrieved 2016-03-10.
6. "Plášilite: Plášilite mineral information and data". Mindat.org. Retrieved 2016-03-10.
7. "Belakovskiite: Belakovskiite mineral information and data". Mindat.org. Retrieved 2016-03-10.
8. "Meisserite: Meisserite mineral information and data". Mindat.org. Retrieved 2016-03-10.
9. "Blue Lizard Mine, Chocolate Drop, Red Canyon, White Canyon District, San Juan Co., Utah, USA - Mindat.org". Mindat.org. Retrieved 2016-03-10.