The salt ooids of Berre salt works (Bouches du Rhône, France): the role of bacteria in salt crystallisation

Salt ooids that form in the solar salt works of Berre (France) are studied principally through SEM imagery. They are compared to halite particles obtained in the laboratory by bacterial mediation under controlled conditions. Salt crystallisation appears to be induced and oriented by the growth of bacterial colonies. The main bacterial processes involved are the multiplication of cells and the regulation of their internal salt concentration which tends to oversaturate the closely neighbouring environment. Such biogeological processes could have played a significant role in rocksalt deposition over geological times.