Apatite-type SrPr(4)(SiO(4))(3)O

Single crystals of the title compound, strontium tetra­praseo­dymium tris­(silicate) oxide, SrPr(4)(SiO(4))(3)O, have been grown by the self-flux method using SrCl(2). The structure is isotypic with the apatite supergroup family having the generic formula (IX) M1(2) (VII) M2(3)((IV) TO(4))(3) X, where M = alkaline earth and rare earth metals, T = Si and X = O. The M1 site (3.. symmetry) is occupied by Pr and Sr atoms with almost even proportions and is surrounded by nine O atoms forming a tricapped trigonal prism. The M2 site (m.. symmetry) is almost exclusively occupied by Pr and surrounded by seven O atoms, forming a distorted penta­gonal bipyramid. The Si atom (m.. symmetry) is surrounded by two O (m.. symmetry) and two O atoms in general positions, forming an isolated SiO(4) tetra­hedron. Another O atom at the inversion centre ([Image: see text].. symmetry) is surrounded by three M2 sites, forming an equilateral triangle perpendicular to the c axis.