A neodymium borosilicate, Mg(2)Nd(13)(BO(3))(8)(SiO(4))(4)(OH)(3) (MgNdBSi-1), was obtained from a high-temperature (1400 °C), solid-state reaction under high-pressure conditions (4.5 GPa). MgNdBSi-1 contains six different types of Nd(3+) coordination environments with three different ligands: BO(3), SiO(4), and OH groups. Mg(2+) cations are only bond to BO(3) groups and form porous two-dimensional layers based on 12-membered ring fragments. Surprisingly, the OH groups are retained at high temperature and reside at the center of Mg-BO(3) rings.