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  DOI Prefix   10.20431


 

International Journal of Mining Science
Volume 5, Issue 2, 2019, Page No: 18-34

The Geology, Geochemistry and Mineralogy of Beryl Mineralization in Zabara Area, South Eastern Desert, Egypt

Khaleal F. M.1, El-Bialy M. Z. 2, Saleh G. M.1*, Ibrahim W. S.1, El Dawy M. N.1

1. Nuclear Materials Authority, P.O. Box 530, El Maadi, Cairo, Egypt.
2. Faculty of Science, Port Said University; Port Said, Egypt

Citation : Saleh G. M.,et.al, The Geology, Geochemistry and Mineralogy of Beryl Mineralization in Zabara Area, South Eastern Desert, Egypt International Journal of Mining Science 2019, 5(2) : 18-34.

Abstract

This study deals with the geology, geochemistry and mineralogy of the beryl mineralization in the Zabara area, South Eastern Desert (SED), Egypt. The rock units which are exposed in Zabara area granite gneisses, serpentinites, melange rocks, metavolcanics and post granite dykes and veins. The rock units which are exposed in the beryl mines area at Wadi (W.) Zabara area are gneiss rocks and schist rocks as well as quartz veins. The contact between the gneisses and overlying schists is thrust contact trending NNW and dipping 38° toward NE. The schists represent the most predominant rock unite within Zabara beryl mines area, covering about 1.0 Km2. It is composed mainly of different varieties of schists such as hornblende schist, quartzo-feldspathic schist and garnet biotite schist. In some of these schists (phlogopite schist), beryl crystals are disseminated. The beryl mineralization is restricted to the contact between the schist rocks and gneiss rocks. These schists are dissected by number of quartz veins; some of them are beryl bearing veins, whereas the others are barren. The beryl crystals are of small size, fractured and pale green in color. The good quality of beryl with green grass color (emerald) could be found in phlogopite schist.

The beryl crystals were confirmed by both X-Ray Diffraction (XRD) and Scan Electron Microscope (SEM). The XRD study revealed that in the case of the quartz hosted beryl it displayed beryl peaks as the major phase with minor amount of quartz peaks suggesting that the beryl crystals were fractured and filled by quartz. The beryl peaks are associated with muscovite peaks in case of phlogopite schist hosted beryl suggesting that the beryl crystals were fractured and filled by schist.

The environmental scan electron microscope (ESEM) study (EDAX) analysis of the beryl crystals in W. Zabara area displayed the appearance of Na, Mg, Al, Si, K, Ca and Fe elements. Beryl of W. Zabara area has high values of Mg, K and Fe. Ti appeared in quartz-hosted beryl, whereas Ni appeared in phlogopite schist-hosted beryl.

The spectrometric study within W. Zabara area revealed that the gneiss rocks have K% contents of (3.89%). This is higher than the schist rocks (1.8%). The gneiss rocks have eU and eTh contents as (10.05 & 33.47) respectively; these values are higher than those of schists (1,8& 3.05) respectively. The average of eU/eTh ratio for gneisses (0.32) is lower than the average value of eU/eTh ratio for schists (1.01). The gneiss rocks at W. Zabara area are relatively abnormal case as the corresponding crustal average values.

The gneiss rocks of W. Zabara area have higher contents of Al2O3, MgO, Na2O and P2O5 than gneisses rocks at Abu Rusheid area (the highest radioactive anomaly in Egypt). On the other hand, Abu Rusheid gneiss rocks have higher values of SiO2, TiO2, K2O and MnO than those in W. Zabara area. The schist rocks have higher values of SiO2, K2O and TiO2 than those in Wadi El Gemal area. On the other hand, Wadi El Gemal schist rocks have higher values of Al2O3, MgO, Na2O, P2O5 and MnO than those in Zabara area.


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