Stibivanite, Sb2VO5, is a bright green fibrous to platy (elongated c) mineral, found associated with stibnite and various sulphosalts. Micro-indentation hardness is VHN50 = 232
(148-286). Optical data are: 2Valpha 85o(+ or -1o); alpha > 1.87, gamma < 1.89; b = alpha , c : gamma approx 0o; r >> v; length slow; pleochroism beta emerald green, gamma olive green, alpha emerald green with olive tint. It is moderately
anisotropic (light to dark grey) in reflected light, with green to yellowish internal reflections. Electron microprobe analysis gave Sb2O3 79.31, VO2 22.01, = 101.32. Indexed powder diffraction data and methods of synthesis are given. (For structural
details see M.A. 82M/0171)-M.I.C.