Roselite is a rare arsenate mineral with chemical formula: Ca2(Co,Mg)[AsO4]2·H2O.

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.

[2] It occurs in cobalt-bearing hydrothermal environments and was associated with veins of quartz and chalcedony in the type locality.

[2][4] It has also been reported from Italy, Morocco, Chile, British Columbia and several locations in Germany.

[2] The pleochroism of roselite depends on chemical composition with darker-rose-colored varieties higher in cobalt content and lighter-rose-colored varieties higher in calcium and magnesium content (Palache et al., 1960).