Mineralogy of Aragonite Carbonate Veins, Dissecting Dokhan Volcanics, Northern Eastern Desert, Egypt

The aragonite carbonate veins are hard with bone-like appearance, associated with carbonate-rich basic dykes. All are hosted in andesitic and basaltic volcanic rocks of Dokhan type and. The carbonate rocks are composed of ultra fine grains of aragonite with minor phases of calcite, magnesite and cerussite as detected by x-ray diffraction (XRD) and differential thermal analysis (D. T. A). They are of calcite carbonate according to IUGS with CaO (56.1 Wt %), MgO %), L. O. I. (31Wt %) and poor in Sr, Ba, Y, REEs, Cr, V, Ni, Ti, Co, V but rich in Pb and Zn elements than those of magmatic carbonate rocks. This suggests hydrothermal crystallization of aragonite under low temperature and high C2O gas pressure.