Facies and geochemistry of non-marine gypsum, EMISAL, Egypt - Ali-Bik, M. W. (National Research Centre. Geological Sciences Department(Egipte)) ; Metwally, H. I. M. (National Research Centre. Geological Sciences Department (Egipte)) ; Wali, A. M. A. (Cairo University (Egipte). Geology Department) ; Kamel, M. G. (Academy of Scientific Research and Technology (Egipte))