Meisserite
A very rare sodium uranyl sulfate carrying a hydrosulfate anion — a feature it shares with belakovskiite.
Intro adapted from Wikipedia (CC BY-SA).
Meisserite is an IMA-recognized mineral species in the sulfate class, with the chemical formula Na₅(UO₂)(SO₄)₃(SO₃OH)(H₂O).
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2; specific gravity 3.208; Very pale yellow streak; Vitreous. Bright yellow-green fluorescence under LW and SW UV luster; optically biaxial.
IMA symbol Mss, IMA status: approved, named in 2013.
Occurs as efflorescences on sandstone in the underground workings of a roll-front type uranium deposit, the product of weathering and oxidation of primary uraninite.
It is found associated with Chalcanthite, copiapite, ferrinatrite, blödite, gypsum, johannite, belakovskiite.
The mineral was named to honor Nicolas Meisser (b. 1964), Swiss mineralogist and Curator of Mineralogy and Petrography, Cantonal Museum of Geology, Lausanne, Switzerland.