Evaporite basins equilibrate inflow and outflow in the gypsum saturation field, unless synsedimentary subsidence destroys the equilibrium. Anaerobic bacteria destroy sulfate ions, thiobacteria and cyanophyta reconstitute them on sun-lit shelves; protein-, alcohol- and chlorophyll derivatives extensively control the sequence of primary precipitates and their alterations. The brine concentrates to chloride precipitation, depleting first sodium, then potassium ions, and dissolves all blown-in quartz and feldspar grains. Permian and Neogene potash deposits were secondarily sulfatized worldwide. This is deemed to have happened by meteoric waters dissolving gypsum beds on marginal shelves dried out during low sea level positions or in evaporites accessed by deformation. A lateral influx of calcium and sulfate ions, that dissolve more easily in an Na-Cl-enriched brine, can explain all products of K-Mg-sulfatization.