Luboržákite
Luboržákite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Mn₂AsSbS₅.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Pavonite structural group.
Key properties: Mohs hardness 4–4.5; specific gravity 4.181; Black streak; Metallic luster.
IMA symbol Lbž, IMA status: approved, named in 2020.
Found in a gold deposit in metasomatites (skarns, argillisites and jasperoids) that replace volcanogenic-sedimentary rocks and limestones. Brecciated metasomatites host Mn-Tl-Hg-As-Sb mineralization.
It is found associated with Manganiferous dolomite and calcite, pyrite, orpiment, realgar, stibnite, aktashite, alabandite, boscardinite, chabournéite, coloradoite, clerite, écrinsite.
The mineral was named to honor Czech crystallographer Professor Lubor Žák (1925-2008), Charles University, Prague, Czech Republic.