Gold - electrum relationships in Wadi Hammad, Eastern Desert, Egypt

• Autorzy: Osman A. M. , Kucha H. , Piestrzyński A.

Warianty tytułu

PL

Relacje złoto rodzime – elektrum w wadi hammad, wschodnia pustynia, Egipt

• Języki publikacji: EN

Abstrakty

EN

Gold mineralization in Wadi Hammad reveals close spatial relationship with the pre-existing distribution of electrum in galena. Mineralization is confined to quartz veinlets and stockwork between shared volcanics and post-tectonic pink granite. The ore forming minerals include in decreasing order of abundance: galena, pyrite, chalcopyrite, sphalerite, bornite and enargite. Galena forms small clusters and disseminations of quartz. In the fractured section of veins and veinlets galena and other sulphides are converted into oxides and carbonates, containing very fine gold grains. Microprobe analyses inside galena reveal the presence of electrum as micro-blebs 5 µm in size, containing 53.1 wt.% Au, 44.57 wt.% Ag, 1.27 wt.% Pb and minor amounts of As, Sb and Hg. Electrum has also been detected in carbonate rocks hosting Fe-Pb-oxides in fissures between shared-corroded quartz. The gold in quartz microfissures attains high purity. Similar gold occurs in goethite fillings. It is suggested that galena was the main primary host to the electrum (rich-silver type). During successive stage of mobilisation (weathering) galena and other sulphides were converted into oxides and carbonates, while silver and gold were leached out and reprecipitated in the form of low-silver gold occurring as inclusions in Pb-Fe carbonates and oxides that fill fissures.

PL

Stwierdzono, że złoto rodzime wykazuje przestrzenną korelację z pierwotnym okruszcowaniem reprezentowanym przez elektrum i galenę. Okruszcowanie Au jest związane z kwarcowymi żyłami i sztokwerkiem w strefie zuskokowanych skał wulkanicznych i w strefie kontaktu tych skał z post-tektonicznym granitem. W strefie okruszcowanej występują: galena, piryt, chalkopiryt, sfaleryt, bornit i enargit. W strefach tektonicznych pierwotne okruszcowanie jest zastąpione minerałami tlenowymi: cerusytem, Pb-nośnym tlenkiem żelaza, goethytem i węglanami. Złoto występujące w asocjacji z minerałami tlenowymi jast wysokiej próby, elektrum zaś stanowi podstawową fazę współwystępującą z siarczkami. Przypuszczalnie elektrum było związane z galeną. W czasie utleniania złoto uległo powtórnej krystalizacji w postaci drobnych agregatów rozproszonych w asocjacji tlenków Fe i węglanów wypełniających spękania i inne wolne przestrzenie.

Słowa kluczowe

EN

Wadi Hammad; Egypt; gold; electrum; lead-bearing oxides

PL

złoto; złoto rodzime; elektrum; Egipt

• Wydawca: Mineralogical Society of Poland
• Czasopismo: Mineralogia
• Rocznik: 2000
• Tom: Vol. 31, iss. 2
• Strony: 17--26 + 2 k. tab.
• Opis fizyczny: Bibliogr. 23 poz., rys., tab.

Twórcy

autor

Osman A. M.

• Dept. of Geology, Ain Shams University, Cairo, Egypt

autor

Kucha H.

• University of Mining and Metallurgy, al. Mickiewicza 30, 30-059 Kraków, Poland

autor

Piestrzyński A.

• University of Mining and Metallurgy, al. Mickiewicza 30, 30-059 Kraków, Poland

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