Geochemistry of Economic Heavy Minerals from Rosetta Black Sand of Egypt

Abstract

The potential heavy minerals content of the black-sand resources in Rosetta is investigated using optical microscopy, X-ray diffraction, scanning electron microscope, electron-microprobe analysis and inductively coupled plasma-mass spectrometry. The separation of individual minerals was done by wet-gravity and applying magnetic and electric approaches. The composition and morphology of the studied heavy minerals such as zircon, monazite, garnet, magnetite, ilmenite and rutile are compared with their equivalents in the Nile sources to elucidate their fate during the long transportation. Shukri's samples of the Nile sediments that were collected and studied during the mid-twentieth Century are adopted for this comparison. Generally, mineral grains turn to be polished and free of contamination upon long transportation while others are entirely lost before reaching the influx. Even the ultrastable minerals such as zircon and monazite experienced some changes in their chemical composition during transportation. The REE geochemistry suggests that the coarse grained zircon was possibly derived from highly fractionated and altered pegmatitic rocks of White Nile proximity while the fine grained variety was derived from the Ethiopian hinterlands. Two monazite varieties are distinguished, namely; Ce-monazite and Th-monazite, however, the extreme Eu deficiency (ΔEu= <0.1) is used to assign derivation from highly fractionated felsic sources. Garnet belongs essentially to alamandine variety is derived from metamorphic rocks such as the prevailing twomica schist of White Nile provenance. The opaque minerals; magnetite, ilmenite and rutile have nearly flat chondrite-normalized REE patterns but with slight enrichment in LREE. These minerals are good indicators of the volcanic source of the Ethiopian plateau. Few gold grains have been detected in the high grade cassiterite concentrate with average concentration of 7780 ppb Au. The 70 A.A. El-Kammar et al. radioactivity in the studied black sands is essentially attributed to both uranium and thorium series mostly related to monazite, zircon, garnet and ilmenite.

Separation, reserve estimation and radioactivity responsibility of the economic heavy minerals of East El- Arish black sand, North Sinai, Egypt

“…S1d) is derived from mafic and ultramafic igneous rocks. The results are compatible with El-Kammar 8 , who stated that titano-magnetite minerals, such as magnetite, ilmenite, leucoxene, and rutile, are mainly derived from mafic volcanic rocks of Blue Nile provenance.…”

“…Fe-Ti minerals such as magnetite, ilmenite, and rutile came from the volcanic rocks on the Ethiopian plateau, transported by the Nile River. 8 In terms of TiO 2 %, the studied rutile is classified into two types: high-grade rutile with TiO 2 ~ 95 wt% (Fig. S10c, d) and low-grade rutile with TiO 2 ~ 88 wt % (Fig.…”

Risk assessment of radioactive hazards associated with black sand upgrading processes

“…As an example, El-Burbllus black sand processing flowsheet was among different suggested concentration flowsheets (El-Afandy et al 2016). These minerals are rich in appreciable concentrations of economic minerals along with some radioactive elements in concentrations higher than the ordinary global level, nevertheless, they do not necessarily have the same radiological indices or even exceed the permissible radiation limits (El-Kammar et al 2011; Abdel-Karim et al 2016). The inhalation of these minerals during their processing is one of the main threats, which depends mainly on the particle size and requires proper ventilation (Adelikhah et al 2020; Dodge-Wan and Viswanathan 2021; Kocsis et al 2021).…”