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Mineralogical and Geochemical Characterization of Beryl‐Bearing Granitoids, Eastern Desert, Egypt: Metallogenic and Exploration Constraints
Author(s) -
Abdalla Hamdy M.
Publication year - 2009
Publication title -
resource geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 43
eISSN - 1751-3928
pISSN - 1344-1698
DOI - 10.1111/j.1751-3928.2009.00085.x
Subject(s) - pegmatite , geology , greisen , geochemistry , alkali feldspar , albite , cassiterite , wolframite , mineral , mineralogy , quartz , feldspar , fluid inclusions , tin , chemistry , tungsten , paleontology , organic chemistry
Mineral chemistry and geochemical characteristics of beryl‐bearing granitoids in Eastern Desert of Egypt, were examined in order to identify the metallogenetic processes of the host granitoids. The investigated Be‐bearing granitoids and type occurrences are classified into two groups: (i) peraluminous, Ta ≥ Nb + Sn + Be ± W‐enriched, Li‐albite granite (e.g. Nuweibi and Abu Dabbab); and (ii) metasomatized, Nb >> Ta + Sn + Be ± W ± Mo‐enriched alkali feldspar granite (i.e. apogranite; e.g. Homr Akarem, Homr Mikpid and Qash Amir). In these two groups, beryl occurs as stockwork greisen veins, greisen bodies, beryl‐bearing cassiterite ± wolframite quartz veins, dissemination, and miarolitic pegmatites. Beryl of the Be‐granitoids, particularly those of miarolitic pegmatites, contains appreciable contents of Fe, Na, and H 2 O. An important feature of the Be‐apogranites is the occurrence of white mica as the sole mafic mineral in the unaltered alkali feldspar granite in lower zones. Presence of white mica as volatile‐rich pockets suggests that the melt underwent disequilibrium crystallization, rapid nucleation rates, and exsolving and expulsion of volatiles.