These hurdles have stimulated the development of a solution-based processing method for gypsum using hyper-saline brines (> 4 M), as a simple yet effective way to control the stability ranges of the different calcium sulfate phases. We demonstrate that in (hypersaline) brines, it is possible to produce calcium sulfate hemihydrate in a rapid and cyclic manner. Importantly, this approach allows for total flexibility in the choice of source materials, be it raw or waste gypsum , or through the direct mixing of solutions containing calcium and sulfate ions . Another major advantage of this method, compared to solid state and autoclave methods, is that all the transformations take place in an aqueous medium at temperatures well below the boiling point of water . Liquid water solutions inherently have a high heat capacity, which can help reduce energy losses during the bassanite synthesis processes. By using insulated, closed-loop reactors, we can further improve energy efficiency and optimize the production of calcium sulfate hemihydrate, making the process even more attractive from an economic and environmental perspective.