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Nusab El Balgum area
southwestern Desert, Egypt, is consists mainly of sandstone
(Devonian), volcanic rocks (Permo-Triassic), altered
granitic rocks and post granitic dykes. The altered granitic
rocks are classified microscopically to silicified granite
and kaolinized granite. The most important types of wall
rock alteration are sericitization, silicification,
carbonization, hematization chloritization and kaolinization).
The recorded gold contents in Nusab El Balgum area,
southwestern Desert of Egypt in the silicified granite (9 to
0.3 g/t) is more than kaolinized granite (0.3 g/t) ,
pyroclastics (0.3g/t)and post granitic dykes(0.5g/t) and
considered as first record in association with rare
metals(Ni, Ag, Zn, Pb ,Th , U ,Ga ,W and Mo). The
mineralogical studies confirm the presence of three
mineralization stages, the earliest mineralization stage
(high temperature stage) is characterized by the formation
of native Au associated with hypogene rare metals (pyrite,
galena, sphalerite and native Ni). The second stage
(lower-temperature) is characterized by the formation of
supergene secondary minerals; uranium, barite and atacamite.
Third stage is related to carbonate facies formed after the
oxide (supergene alteration). The rare metals enrichment in
the study area are formed due to the subsequent processes;
including the ascending hydrothermal solutions (alkaline
followed by acidic hydrothermal solutions), with further
contribution of the descending acidic meteoric water;
supergene enrichment processes. The origin of uranium
appears to be closely associated with the rare metals
mineralization and may be reflects readily their intimate
coherence.
Keywords: Hydrothermal solutions, Nusab El Balgum,
auriferous, rare metals, thorite, gold
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