A new uranyl silicate, K(6)(UO(2))(3)Si(3)O(22), was synthesized by a flux method and characterized by single-crystal X-ray diffraction, solid-state NMR, and photoluminescence spectroscopy. The 3D framework structure contains UO(6) tetragonal bipyramids and a new type of (Si(8)O(22))(12-) unit. K(6)(UO(2))(3)Si(8)O(22), C2/m (No.12), a = 1.24092 (9) nm, b = 1.45678 (8) nm, c = 0.81199 (5) nm, beta = 103.992 (4)degrees, V = 1. 4240(1) nm(3), Z = 2, R(1) = 0. 0329 and wR(2) = 0. 0796.
