cesanite

{{Infobox mineral | name = Cesanite | category = Sulfate minerals | boxwidth = | boxbgcolor = | image = Cesanite.jpg | imagesize = | caption = | formula = Ca2Na3[(OH)(SO4)3] | IMAsymbol=Csa | molweight = | strunz = 7.BD.20 | system = Hexagonal | class = Trigonal dipyramidal (m) H-M symbol: () | symmetry = P | unit cell = a = 9.44 Å, c = 6.9 Å; Z = 1 | color = Colorless to white | habit = Massive granular, rarely as striated subhedral prismatic crystals | twinning = On {100} | cleavage = On {0001} | fracture = | tenacity = | mohs = 2-3 | luster = Greasy to silky in aggregates | polish = | refractive = nω = 1.570 nε = 1.564 | opticalprop = Uniaxial (-) | birefringence = | dispersion = | pleochroism = | fluorescence= | absorption = | streak = | gravity = 2.96-3.02 | density = | fusibility = | diagnostic = | solubility = Slight in water | diaphaneity = Transparent to translucent | other = | references = }}

Cesanite is the end member of the apatite-wilkeite-ellestadite series that substitutes all of apatite's phosphate ions with sulfate ions and balances the difference in charge by replacing several calcium ions with sodium ions. Currently very few sites bearing cesanite have been found and are limited to a geothermal field in Cesano, Italy from which its name is derived, Măgurici Cave in Romania, and in the San Salvador Island caves in the Bahamas.