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

Abstract

AbstractThe new minerals fermiite (IMA2014-068), Na4(UO2)(SO4)3·3H2O and oppenheimerite (IMA2014-073), Na2(UO2)(SO4)2·3H2O, were found in the Blue Lizard mine, San Juan County, Utah, USA, where they occur together as secondary alteration phases in association with blödite, bluelizardite, chalcanthite, epsomite, gypsum, hexahydrite, kröhnkite, manganoblödite, sideronatrite, tamarugite and wetherillite.Fermiite descriptive details: pale greenish-yellow prisms; transparent; vitreous lustre; bright greenishwhite fluorescence; white streak; hardness (Mohs) 2½; brittle; conchoidal fracture; no cleavage; slightly deliquescent; easily soluble in RT H2O; densitymeas = 3.23(2) g cm–3; densitycalc = 3.313 g cm–3. Optically, biaxial (+), α = 1.527(1), β = 1.534(1), γ = 1.567(1) (white light); 2Vmeas.= 51(1)°, 2Vcalc.= 50°; dispersionr<v, distinct. Pleochroism:X,Y= colourless,Z= pale greenish yellow;X=Y<Z. Energy dispersive spectroscopic (EDS) analyses yielded the empirical formula Na3.88(U1.05O2)(S0.99O4)3(H2O)3. Fermiite is orthorhombic,Pmn21,a= 11.8407(12),b= 7.8695(5),c= 15.3255(19) Å,V= 1428.0(2) Å3andZ= 4. The structure (R1= 2.21% for 1951Io> 3σI) contains [(UO2)(SO4)3] chains that are linked by bonds involving five different Na–O polyhedra to form a framework. The mineral is named for Italian-American theoretical and experimental physicist Dr. Enrico Fermi (1901–1954).Oppenheimerite descriptive details: pale greenish-yellow prisms; transparent; vitreous lustre; bright greenish-white fluorescence; white streak; hardness (Mohs) 2½; slightly sectile; three good cleavages, {110}, {011} and {101}; irregular fracture; slightly deliquescent; easily soluble in RT H2O; densitycalc = 3.360 g cm–3. Optically, biaxial (+), α = 1.537(1), β = 1.555(1), γ = 1.594(1) (white light); 2Vmeas.= 72(2)°, 2Vcalc.= 70°; dispersion isr>v, moderate, inclined; optical orientation:X≈ ⊥ {101},Z≈ [111]; pleochroism: X very pale greenish yellow, Y pale greenish yellow, Z greenish yellow; X < Y < Z. EDS analyses yielded the empirical formula Na1.94(U0.97O2)(S1.02O4)2(H2O)3. Oppenheimerite is triclinic,P1,a= 7.9576(6),b= 8.1952(6),c= 9.8051(7) Å, α = 65.967(5), β = 70.281(5), γ = 84.516(6)°,V= 549.10(8) Å3andZ= 2. The structure (R1= 3.07% for 2337Io> 3σI) contains [(UO2)(SO4)2(H2O)] chains that are linked by bonds involving two different Na–O polyhedra to form a framework. The mineral is named for American theoretical physicist Dr. J. Robert Oppenheimer (1904–1967).