1·The rare earth ions lie between the disilicate groups and the sheets of octahedra to form (8+3)-coordinated A(1)-polyhedra and 10-coordinated A(2)-polyhedra.
稀土离子位于双硅酸根和八面体层之间，形成（ 8+3 ）配位的A（ 1）多面体和10配位的A（ 2 ）多面体。