Fig. 1. (a) Projection of the crystal structure of buetschliite along [100] based on the structural data of Effenberger and Langhof.23 Calcium atoms are coordinated by six nearest oxygen neighbours from adjacent carbonate groups in form of octahedra (shown in light blue). Potassium atoms (yellow) are surrounded by nine oxygen ligands. Oxygen and carbon atoms are presented as red and black spheres, respectively. (b) Top view of a single layer (z ≈ 0) of CaO6-octahedra and planar carbonates groups. (c) Top view of a single layer (z ≈ ⅙) containing K-cations and planar carbonate groups.
