fontarnauite

{{Infobox mineral | name = Fontarnauite | boxwidth = | boxbgcolor = | image = Fontarnauita.jpg | imagesize = 260 | alt = | caption = Fontarnauite, Anatolia, West Turkey | category = Borate minerals | formula = | IMAsymbol = Fon | molweight = | strunz = 6.DA.60 | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/c | unit cell = | color = Light brown | colour = | habit = | twinning = | cleavage = Perfect {010} | fracture = | tenacity = | mohs = 2.5 - 3 | luster = | streak = | diaphaneity = | gravity = | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Fontarnauite is a relatively recently described, rare sulfate, borate mineral with the chemical formula . It is found in an evaporite boron deposit. It coexists with other evaporite boron minerals, especially probertite. It is monoclinic, crystallizing in the space group P21/c.