Polycrystalline K 4 CaSi 6 O 15 was prepared from (i) solid-state reactions between stoichiometric mixtures of the corresponding oxides/carbonates and (ii) combustion solution synthesis using Kand Ca-nitrates, tetraethyl orthosilicate (TEOS) and glycine (fuel component) as starting reagents.The compound was characterized by powder X-ray diffraction. Differential thermal analysis indicated that K 4 CaSi 6 O 15 melts congruently at about 956 °C. On cooling down from the liquid state, a distinct glass-forming tendency was observed. Single-crystals suitable for further structural investigations were obtained from sinter experiments just below the melting point.Basic crystallographic data are as follows: monoclinic symmetry, space group P c, a = 6.9299(2) Å,