fianelite

{{Infobox mineral | name = Fianelite | category = Vanadate | image = | caption = | formula = Mn2V(V,As)O7 · 2H2O | IMAsymbol = Fnl | molweight = | strunz = 08.FC.05 | system = Monoclinic | class = 2/m | symmetry = P21/n | unit cell = a = 7.809;Å, b = 14.554;Å c = 6.705 Å, β = 93.27(3)◦ | color = Orange-Red | habit = Platy | twinning = None observed | cleavage = Good on {001} and {100} | fracture = | tenacity = | mohs = 3 | luster = Vitreous | polish = | refractive = 1.85±0.02 | opticalprop = | birefringence = δ=1.820 | dispersion = Good | pleochroism = | fluorescence= | absorption = | streak = | gravity = 3.22 gm/cc | density = 3.21 g/cm3 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent | other = | references = }}

Fianelite is a mineral belonging to the manganese vanadate category, found in iron-manganese ores. Named after the place where it was found, Fianel, a mine located in Val Ferrera (Ferrera valley), in the canton of Graubünden, Swiss. This mineral is found in small amounts in metamorphosed iron-manganese ores. This is the last crystallization of vanadate at the site since medaite was the last vanadate mineral being crystallized, but because of retrograde metamorphism, occurring at the place, vanadium moved into medaite veinlets, forming cross-cutting fianelite on medaite.