The melilite group includes: åkermanite: Ca2MgSi2O7 alumoåkermanite: (Ca,Na)2(Al,Mg,Fe2+)(Si2O7) bennesherite: Ba2Fe2+Si2O7 gehlenite: Ca2Al(SiAl)O7 hardystonite: Ca2ZnSi2O7 Back to Minerals