Vésigniéite is a rare barium copper hydroxyl vanadate, first discovered in Thuringia (Germany). It is named after Louis Vésignié (1870–1954), a French mineral collector and former president of the Mineralogical Society of France.
In this specimen, volborthite —occurring as light green tabular crystals— coexists with dark green vésigniéite. The sample exhibits slight radioactivity, likely due to the presence of vanadates such as tyuyamunite, Ca(UO₂)₂(VO₄)₂·5-8H₂O, or carnotite, K₂(UO₂)₂(VO₄)₂, in the matrix. Good crystal size for the species.