Vésigniéite Locality: Floßberg Mine, Bad Lauterberg, Harz, Lower Saxony, Germany Field of view 6 mm. — Photo: Leon Hupperichs · CC BY-SA 3.0
Vésigniéite
Vésigniéite is an IMA-recognized mineral species in the vanadate class, with the chemical formula Cu₃Ba(VO₄)₂(OH)₂.
It crystallizes in the monoclinic crystal system (space group C2/m).
Key properties: Mohs hardness 3–4; specific gravity 4.56; Greenish streak; Vitreous luster; optically biaxial.
IMA symbol Vsg, grandfathered status — known before the IMA’s founding, named in 1955.
A rare secondary mineral formed in copper-bearing U–V deposits.
It is found associated with Volborthite, malachite, tyuyamunite, carnotite, barite, calcite.
The mineral was named to honor Colonel Jean Paul Louis Vésignié (1870–1954), noted French mineral collector.