Details

Autor(en) / Beteiligte

• Kampf, Anthony R
• Plasil, Jakub
• Olds, Travis A
• Nash, Barbara P
• Marty, Joe

Titel

Uranoclite, a new uranyl chloride mineral from the Blue Lizard Mine, San Juan County, Utah, USA

Ist Teil von

• Mineralogical magazine, 2021-06, Vol.85 (3), p.438-443

Ort / Verlag

London: Mineralogical Society

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The new mineral uranoclite (IMA2020-074), (UO2)2(OH)2Cl2(H2O)4, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of irregular yellow crystals in a secondary assemblage with gypsum. The streak is very pale yellow and the fluorescence is bright green-white under 405 nm ultraviolet light. Crystals are translucent with vitreous lustre. The tenacity is brittle, the Mohs hardness is ∼1.5, the fracture is irregular. The mineral is soluble in H2O and has a calculated density of 4.038 g·cm-3. Electron microprobe analyses provided (UO2)2(OH)2.19Cl1.81(H2O)4. The six strongest powder X-ray diffraction lines are [dobs À(I)(hkl)]: 8.85(38)(002), 5.340(100)(200, 110), 5.051(63)(202), 4.421(83)(112, 004, 202), 3.781(38)(212) and 3.586(57)(014, 204). Uranoclite is monoclinic, P21/n, a = 10.763(8), b = 6.156(8), c = 17.798(8) À, β = 95.656(15)°, V = 1173.5(18) À3 and Z = 4. The structure is the same as that of synthetic (UO2)2(OH)2Cl2(H2O)4 in which the structural unit is a dimer consisting of two pentagonal bipyramids that share an equatorial OH-OH edge. The dimers are linked to one another only by hydrogen bonding. This is the second known uranyl mineral containing essential Cl and the first in which Cl coordinates to U6+.