Mineralogical and Geochemical Characterization of Beryl‐Bearing Granitoids, Eastern Desert, Egypt: Metallogenic and Exploration Constraints

Abstract

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 Ն Nb + Sn + Be Ϯ W-enriched, Li-albite granite (e.g. Nuweibi and Abu Dabbab); and (ii) metasomatized, Nb >> Ta + Sn + Be Ϯ W Ϯ 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 Ϯ wolframite quartz veins, dissemination, and miarolitic pegmatites. Beryl of the Be-granitoids, particularly those of miarolitic pegmatites, contains appreciable contents of Fe, Na, and H2O. 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.

Non-pegmatitic beryl related to Carboniferous granitic magmatism, Velasco Range, Pampean Province, NW Argentina

“…This is consistent with the findings by Staatz et al (1965) and Abdalla (2009), who stated that beryl in pegmatites usually has lower Fe contents than that in granitoids. In turn, FeO t values of beryl from the La Chinchilla Stock fall within the compositional range of beryl from leucogranites (Abdalla, 2009;Hall and Walsh, 1971), while they are usually higher than those of beryl from hydrothermal quartz veins and greisen (Abdalla and Mohamed, 1999), with some exceptions. Notably higher Fe values can be seen in beryl from a rhyolite and in beryl+phenakite veins (3.6 wt% FeO t ; Abrecht and Hänni, 1979).…”

“…It is a highly evolved leucogranite that has the particularity of containing beryl as an accessory mineral in certain sectors of the stock. This stock represents one of the scarce examples of beryl-bearing granitoids (together with those found in the USA: Staatz et al, 1965;central Portugal: Charoy and Noronha, 1996;Charoy, 1999;Ireland: Burke et al, 1964;and central i) Disseminated as magmatic accessory mineral in leucogranites, usually metasomatized ("apogranites") -Stock La Chinchilla, Velasco Range, Argentina (Grosse et al, 2005;Salvatore et al, 2013) -Piedras Coloradas, Las Chacras Batholith, San Luis, Argentina** (Hurlbut and Aristarain, 1969) -Pan-African Massif, Egypt** (Abdalla and Mohamed, 1999;Abdalla, 2009) -Near to Bagdad, Arizona** (Staatz et al, 1965) -Agua Verde, Pima County, Arizona** (Staatz et al, 1965) -Lone Pine, California** (Staatz et al, 1965) -Sheeprock Mountains, Utah, USA** (Staatz et al, 1965;Barton and Young, 2002) -Mt. Antero, Colorado, USA** (Staatz et al, 1965;Barton and Young, 2002) -Rosses Granite, Donegal, NW Ireland (Burke et al, 1964;Hall and Walsh, 1971) -Argemela, Portugal** (Charoy and Noronha, 1996;Charoy, 1999) -Belvis de Monroy pluton, Montes de Toledo Batholith, Cáceres, Spain** (Merino et al, 2013) ii) Hydrothermal veins, essentially composed of quartz -Mesa del Palmar, Achala Batholith, Córdoba, Argentina (Kirschbaum, 1990) -Pan-African Massif, Egypt** (Abdalla and Mohamed, 1999;Abdalla, 2009) -Rosses Granite, Donegal, NW Ireland** (Burke et al, 1964;Hall and Walsh, 1971;Conliffe and Feely, 2006) -Near to Bagdad, Arizona, USA** (Staatz et al, 1965) -Boomer Mine, Lake George, Colorado, USA** (Staatz et al, 1965) -Elfrida, Arizona, USA** (Staatz et al, 1965) -Monte Antero, Colorado, USA** (Staatz et al, 19...…”

“…A. Al 2 O 3 (wt%) versus FeO t +Mg+MnO (wt%); B. FeO t +Mg+MnO (wt%) versus Na 2 O (wt%). References: 1 Sardi and Heimann (2014); 2Abrecht and Hänni (1979); 3Abdalla and Mohamed (1999); 4Staatz et al (1965); 5Hurlbut and Aristarain (1969); 6Hall and Walsh (1971); 7Abdalla (2009); 8Merino et al (2013); 9 Charoy (1999). Abbreviations: Brl: Beryl; Phn: Phenakite.…”

Chemistry of cassiterite in rare metal granitoids and the associated rocks in the Eastern Desert, Egypt

“…2C); ii) beryl, cassiterite ± wolframite quartz veins and iii) placer deposits. A detailed contribution for the petrography of the albitized and greisenized granites is given in Abdalla et al (2008) and Abdalla (2008).…”

“…Detailed geochemical characteristics of the investigated tin -bearing granitoids can be found elsewhere (e.g., Abdalla et al, 2008;Abdalla, 2008).…”