roselite

{{Infobox mineral | name = Roselite | boxwidth = | boxbgcolor = | image = Rosélite, dolomite 7100.2606.jpg | imagesize = 260px | alt = | caption = | category = Arsenate minerals | formula = Ca2(Co2+, Mg)[AsO4]2·H2O+| IMAsymbol = Rsl | molweight = | strunz = 8.CG.10 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = P21/c | unit cell = a = 5.801 Å, b = 12.898 Å c = 5.617 Å; β = 107.42°; Z = 2 | color = Dark rose red, pink | colour = | habit = Elongated crystals and spherical aggregates and druses | twinning = Common as composition plane, contact twins and fourlings | cleavage = {010} Perfect | fracture = | tenacity = | mohs = 3.5 | luster = Vitreous | streak = Light red | diaphaneity = | gravity = 3.69 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.725 nβ = 1.728 nγ = 1.735 | birefringence = | pleochroism = (Dark rose) X: Dark rose, Y: Pale rose, Z: Paler rose (Light rose) X: Pale rose, Y: Paler rose, Z: Palest rose | 2V = Calculated: 68° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = }}

Roselite is a rare arsenate mineral with chemical formula: . It was first described in 1825 for an occurrence in the Rappold mines of Schneeberg, Saxony, Germany and named by Armand Lévy after German mineralogist Gustav Rose. It occurs in cobalt-bearing hydrothermal environments and was associated with veins of quartz and chalcedony in the type locality. It has also been reported from Italy, Morocco, Chile, British Columbia and several locations in Germany.