What is "feodosiyite"

Feodosiyite is a very rare chloride mineral, just recently approved, with the formula CuMgCl(OH)•16HO. Its structure is unique. Feodosiyite comes from the Tolbachik volcano, famous for many rare fumarolic minerals. Chemically similar minerals, chlorides containing both copper and magnesium, include haydeeite, paratacamite-(Mg) and tondiite.