Tokyoite is a rare barium manganese vanadate mineral with the chemical formula: Ba2(Mn3+,Fe3+)OH(VO4)2. It is the manganese analogue of the iron rich gamagarite and the barium analogue of the lead vanadate, brackebuschite. It occurs in low-grade metamorphosed sedimentary manganese ore deposits associated with hyalophane, braunite and tamaite. It w...