Mineral chemistry of polymetallic mineralization associated with altered granite, Hangaliya area, South Eastern Desert, Egypt

Abstract

The Hangaliya gold deposit, located in the South Eastern Desert of Egypt, comprises a series of milky quartz veins along NW-trending Hangaliya shear zone, cutting through granitic rocks of Gabal Nugrus monzogranite. This shear zone, along with a system of discrete shear and fault zones, formed in the late deformation history of the area. The quartz vein emplacement took place under a brittle-ductile shear regime. Auriferous quartz veins are slightly sheared and boudinaged within the shear zone, especially in the hematized granite. Hydrothermal alteration is pervasive in the granitic wall rocks including sericitization, chloritization, fluoritization, sulphidization and minor carbonatization. The altered zones and associating quartz veins contain sulphides, gold, silver, cobalt, bismuth, and uraninite minerals.The Hangaliya gold veins include gold, silver, cobaltite, native bismuth, chalcopyrite, pyrite, galena, ferrocolumbite, fergusonite and uraninite. The Au-ore occurs in the quartz veins and adjacent wall rocks as dissemination in chalcopyrite and pyrite. Presence of refractory native silver, bismuth and cobalt in chalcopyrite is inferred from microprobe analyses. Wall rock sulphidization also likely contributed to destabilising the gold-silver, cobalt, bismuth assemblages and precipitation of the minerals in the hydrothermal alteration zone adjacent to the quartz veins. Gold occurs in two main modes: "invisible gold" in sulphides and native gold. Most of the "invisible gold" occurs in chalcopyrite and bismuth. The altered granites in the Hangaliya shear zone are enriched in Au, Ag, Bi, Co, and Ni with chalcopyrite, which suggests derivation of these metals from serpentinites due to interaction with the felsic Nugrus granite.

Intrusion‐related Gold Deposits in Egypt

“…the Hangalia granite, hosting Hangalia gold deposit, linked with the ~635-630 Ma magmatic pulse of Lundmark et al, 2012). The presence of native bismuth, ferrocolumbite, fergusonite and uraninite in the gold-bearing quartz veins hosted in the Hangalia granite (Raslan and Ali, 2010) confirm the formation of magma by partial melting of the fertilized protolith.…”

“…The ~635 Ma to ~630 Ma magmatic pulses (Lundmark et al, 2012) is an important one in the ANS in the Late Cryogenian (Ali et al, 2012a). As mentioned before, this short magmatic pulse represents a transition from OGDs to IRGDs in the Eastern Desert of Egypt as indicated by the presence of native bismuth, ferrocolumbite, fergusonite and uraninite in the gold-bearing quartz veins of the Hangalia gold deposit (Raslan and Ali, 2010) that is hosted by leucogranite emplaced during the time of this pulse (Lundmark et al, 2012).…”

“…In phase I of the Younger Granites, represented by the Um Rus tonalitegranodiorite (643 ± 9 Ma; Zoheir et al, 2019a), gold mineralization alone exists, with no record for the presence of rare metal mineralization, although Kamel et al (1992) reported the presence of cassiterite in the auriferous quartz veins and schorlite in the alteration zones of the Um Rus gold deposit. The Hangalia granite (638 ± 5 Ma; Lundmark et al, 2012), representing phase II of the Younger Granite (Jakubiak, 1987), hosts the Hangalia gold deposit and, in addition to gold, the Hangalia veins include native bismuth, ferrocolumbite, fergusonite and uraninite (Raslan and Ali, 2010). By the same token, the Fawakhir monzo-to syenogranite (598 ± 3Ma, Andresen et al, 2009) represents phase II of the Gatterian multiphasic Younger Granite and hosts the Fawakhir gold deposit.…”

Source of Raw Materials and Its Processing for the Manufacturing of Ptolemaic Faience Bowls from Tell Atrib (Nile Delta, Egypt)

“…The primary mineralization accompanying the gold-bearing quartz veins comprises mostly magnetite, ilmenite, pyrite, chalcopyrite, sphalerite and galena [51,52]. Moreover, cobaltine and tetrahedrite can also appear [53,54]. The lack of gold in the petrographic and mineralogical analyses in an optical microscope and chemical analysis in SEM-EDS was caused by fine grinding and removal of this metal from quartz, as well as the insufficient resolution of the analyses.…”

Mineralogical study and enhanced gravity separation of gold-bearing mineral, South Eastern Desert, Egypt

“…More than 95 localities of ancient gold mines in the Eastern Desert of Egypt have been reported (Abdel-Rahim et al, 2013;Abdel-Salam et al, 2003). The gold-mineralized, quartzveins are hosted in the granitic rocks and had been extensively exploited since the Pharaonic times until1958 (Raslan and Ali, 2010). The quartz-calcite veins contain about 30 g/t of gold; while the silver content is about 23 g/t (Abdel-Rahim et al, 2013).…”