The new mineral svornostite-(NH4) (IMA2024-068), (NH4)2Mg(UO2)2(SO4)4(H2O)8, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as sprays and subparallel groups of yellow blades in a secondary assemblage with ammoniozippeite, blödite, boussingaultite, gypsum, hexahydrite, kröhnkite, plášilite and quartz. The streak is very pale yellow. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ∼2½, the fracture is curved. The mineral is soluble in H2O and has a measured density of 3.06(2) g·cm–3. The mineral is optically biaxial (+) with α = 1.560(2), β = 1.564(2), γ = 1.589(2); 2V = 43(1)°; orientation: X = a, Y = b, Z = c; pleochroism: X colourless, Y yellow, Z yellow; X < Y ≈ Z. Electron microprobe analyses provided [(NH4)1.895Na0.065K0.040]Σ2.000(Mg0.755Mn0.252)Σ1.007(U0.996O2)2(S1.002O4)4(H1.998O)8. Svornostite-(NH4) is orthorhombic, Pmn21, a = 13.0259(9), b = 8.2909(4), c = 11.2589(4) Å, V = 1215.92(11) Å3 and Z = 2. The crystal structure (R1 = 0.0243 for 2222 I > 2σI reflections) contains uranyl-sulfate chains that are linked into sheets by MgO2(H2O)4 octahedra and 9- and 10-coordinated NH4+ groups. The sheet has the same topology as the sheets in several synthetic uranyl selenates. Svornostite-(NH4) is a member of the newly established svornostite group, which also includes svornostite-(K), oldsite-(K), rietveldite and zincorietveldite.

The new mineral zincorietveldite (IMA2022-070), Zn(UO2)(SO4)2(H2O)5, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as yellow to orange–yellow blades in a secondary assemblage with bobcookite, coquimbite, halotrichite, libbyite, metavoltine, rhomboclase, römerite, tamarugite and voltaite. The streak is very pale yellow. Crystals are transparent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ~2½ and the fracture is curved. Cleavage is excellent on {010}, good on {100} and fair on {001}. The mineral is easily soluble in H2O and has a calculated density of 3.376 g⋅cm–3. The mineral is optically biaxial (+) with α = 1.568(2), β = 1.577(2) and γ = 1.595(2); 2V = 70(1)°. Electron microprobe analyses provided (Zn0.720Mg0.109Fe0.091Mn0.046Co0.035)Σ1.00(UO2)(SO4)2(H2O)5. Zincorietveldite is orthorhombic, Pmn21, a = 12.8712(9), b = 8.3148(4), c = 11.2959(4) Å, V = 1208.90(11) Å3 and Z = 4. Zincorietveldite is the Zn analogue of rietveldite. The structural unit is a uranyl-sulfate chain that is also found in the structures of bobcookite, oldsite, oppenheimerite and svornostite.