Adsorption-Induced Local Amorphization Drives Structural Transformation of Gypsum under Ambient Conditions

The extraction of crystallized water is of significant importance in supporting life, promoting the water cycle, and generating anhydrous minerals. However, extracting crystalline water from hydrated minerals by inducing structural transformation under environmental conditions remains challenging. Our findings reveal a dehydration behavior of gypsum at ambient condition, wherein as few as 3 molecular layers of H₂SO₄ are sufficient to extract crystalline water from gypsum. The ultrathin liquid films adsorbed on the gypsum surface induce the local amorphization of the structure, leading to the dehydration and the following crystallization of anhydrite along specific crystal faces such as (120), (001), (100), and other tautozonal faces. Ab initio molecular dynamics simulations demonstrate that surficial crystalline water in gypsum can be spontaneously drawn into a H₂SO₄ film. Moreover, the local amorphization pathway─measuring approximately 2 nm in scale─exhibits a pronounced energetic advantage over the conventional direct atomic rearrangement mechanism. This insight helps to elucidate the natural processes involving the release of crystalline water from minerals to organisms in arid conditions.