Zálesíite is found to exist as hexagonal prismatic crystals (length: up to 1 mm; width: 10 µm) and fibrous aggregates in the alteration zone in crystalline limestone near gehlenite -spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. The mineral is pale green to emerald green in color with a silky to vitreous luster. Andradite, aragonite, bornite, cahnite, chalcocite, chalcopyrite, conichalcite, johnbaumite, and an unidentified Ca -Cu arsenate mineral coexist in the abovementioned limestone. From SEM -EDS analysis, the empirical formula of zále-síite is found to be (Ca , and Z = 2. It is inferred that zálesíite is formed by the reaction between crystalline limestone, cahnite, johnbaumite, Cu sulfide, and a Bi -rich hydrothermal solution.