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The Role and Implications of Bassanite as a Stable Precursor Phase to Gypsum Precipitation

2012; American Association for the Advancement of Science; Volume: 336; Issue: 6077 Linguagem: Inglês

10.1126/science.1215648

1095-9203

Alexander E. S. Van Driessche, Liane G. Benning, Juan Diego Rodriguez‐Blanco, M. Ossorio, Pieter Bots, Juan Manuel García‐Ruiz,

Minerals Flotation and Separation Techniques

Roundabout Gypsum Calcium sulfates are a common but perhaps underappreciated group of minerals used in a number of natural and industrial processes. In many ways, these crystals precipitate from solution in the same way that most other aqueous minerals form; however, mounting evidence suggests that different, unexplored mechanisms may be at work. Van Driessche et al. (p. 69 ; see the cover) performed high-resolution microscopy of the most common calcium sulfate mineral, gypsum, at various points along time-resolved, fast-quenching growth experiments. The images reveal that gypsum particles actually start out as crystalline nanoparticles of another mineral, bassanite, which then self-assemble into well-ordered nanorods. Finally, the nanorods transform into gypsum following a hydration reaction. The observation that the reaction pathway occurs below the solubility limit of the intermediate phase has wide-ranging implications for biomineralization processes and may provide ways to prevent fouling on the surfaces of desalination membranes.