MgTmS3 is Ilmenite structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent S(1) atoms to form MgS6 octahedra that share corners with nine equivalent Tm(1)S6 octahedra, edges with three equivalent Mg(1)S6 octahedra, and  a faceface with one Tm(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. Tm(1) is bonded to six equivalent S(1) atoms to form TmS6 octahedra that share corners with nine equivalent Mg(1)S6 octahedra, edges with three equivalent Tm(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. S(1) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Tm(1) atoms.
MgTmS3 is Ilmenite structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent S(1) atoms to form MgS6 octahedra that share corners with nine equivalent Tm(1)S6 octahedra, edges with three equivalent Mg(1)S6 octahedra, and  a faceface with one Tm(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. There are three shorter (2.56 Å) and three longer (2.66 Å) Mg(1)-S(1) bond lengths. Tm(1) is bonded to six equivalent S(1) atoms to form TmS6 octahedra that share corners with nine equivalent Mg(1)S6 octahedra, edges with three equivalent Tm(1)S6 octahedra, and  a faceface with one Mg(1)S6 octahedra. The corner-sharing octahedral tilt angles range from 45-58°. There are three shorter (2.66 Å) and three longer (2.71 Å) Tm(1)-S(1) bond lengths. S(1) is bonded in a rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Tm(1) atoms.