Reederite-(Y) is a rare mineral with the formula (Na,Mn,Fe)15(Y,REE)2(CO3)9(SO3F)Cl. It is the only known mineral with fluorosulfate (fluorosulfonate). "REE" in the formula stands for rare earth elements other than yttrium, that is mostly cerium , dysprosium. The formula also includes a Levinson suffix "-(Y)" pointing to the dominance of yttrium at the corresponding site. Reederite-(Y) crystallizes in the hexagonal crystal system with the space group P6, rarely seen among minerals.