\"Celtic sea salt/Sel de Guerande is hand-harvested on the Celtic sea coast in Brittany. It is a nationally preserved area and registered as a World Heritage Site since 2002. The salt is obtained by sun and wind evaporation and it is neither filtered nor cleaned thus it is free of pollutants from mechanical and chemical processes. It contains bio-available minerals and trace elements (calcium, potassium, magnesium, iron, manganese, sulphur, zinc and other nutritive elements). This is why it is grey.\"