de gypse, d’epsomite, d’hexahydrite et de bianchite, des encroûtements de gypse, d’anglésite et de cérussite, et des accumula-tions de jarosite, de goethite et d’hématite. ... of their occurrences and their relationships with the chemical and mineralogical composition of the piles under a given climate is necessary. However, according