Department of Geology, Faculty of Science, Zagazig University, Zagazig, Egypt
ABSTRACT
The Mueilha tin mine area consists of a small greisenised and albitised granite mass with associated quartz carrying some cassiterite and emplaced in a tectonically active region. Geochemical bed-rock sampling was carried out in order to assess the primary mineralization potential of the district and to study the distribution and inter-element relationships of Sn, Nb, W, Pb, Be, Bi, Mo, Y, Zr, Cu and Ti during postmagmatic and hydrothermal processes. Results indicated that apart from the previously known quartz-cassiterite-wolframite mineralisation, disseminated cassiterite occurs in the greisenised and albitised granites. The mineralization, either disseminated or vein, is probably formed by a fluid volatile-rich phase enriched in alkalis. silica and fluorine, developed during the evolution of the granite magma. There are marked differences in the behaviour between Sn, W, Nb, Pb, Be, Mo, Bi, Cu, Zr and Ti during greisenisation, albitisation and hydrothermal processes, probably due to differences in the mobility and stability of their complexes formed under different geological environments. From an economic point of view, the greisenised and albitised granites may be regarded as important future reserves of tin in Egypt, and may represent the upper part of a far larger granite mass which is not exposed.