High- Pressure single-crystal synchrotron X-ray diffraction of kainite (KMg(SO4) Cl 3H2O)

The paper reports the results of high pressure single-crystal X-ray diffraction experiments carried out at the European Synchrotron Radiation Facility (Grenoble, France) on the kainite phase a “mixed salt” sulphate (KMg(SO4) Cl 3H2O). The compressibility and structural modifications are reported up to 14 GPa. The complex structural configuration explains the axial compressibility (with c direction softer than a and b directions) that seems to contrast with the (100) cleavage. Following the structure modification increasing pressure a new sets of hydrogens bonds could form as oxygens and chlorine atoms get at less than 3Å distance from the Ow Kainite is an interesting sulphate mineral because it could be present together with other hydrous minerals in the extra-terrestrial planets (like Mars) and it is a relevant mineral in potash deposits, largely used in the extraction and production of fertilizers. Moreover the simultaneous presence of Cl and H2O makes this mineral interesting to study the behaviour of these two components at high pressure.