Kolskyite, (Ca☐)Na2Ti4(Si2O7)2O4(H2O)7, a group-IV Ti-disilicate mineral from the Khibiny alkaline massif, Kola Peninsula, Russia: Description and crystal structure

Kolskyite, (Ca☐)Na2Ti4(Si2O7)2O4(H2O)7, a group-IV Ti-disilicate mineral from the Khibiny alkaline massif, Kola Peninsula, Russia: Description and crystal structure