The blodite group is a group of minerals with two (in most cases divalent) cations and two anions. The group includes blodite, leonite K2Mg(SO4)2•4(H2O), anapaite Ca2Fe(PO4)2•4(H2O) and schertelite (NH4)2Mg(PO3OH)2•4(H2O).
References
Blodite group Wikipedia(Text) CC BY-SA