Ziesite
Ziesite is a copper vanadate mineral with formula: β-Cu2V2O7. It was discovered in 1980 as monoclinic crystals occurring as volcanic sublimates around fumaroles in the crater of the Izalco Volcano, El Salvador. It is named after Emmanuel G. Zies (1883–1981), an American geochemist who studied Izalco in the 1930s.