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Introduction to pyrite
Abstract
A paper about pyrite mineral and it's physical and chemical properties and it's formation and genesis and the minerals associated with each and economic uses of it
... Weathering of land and rocks including open-pit mining for metals, sulphides and lignite and the smelting of ores are the main sources for sulphate from mine water bearing sulphate such as gypsum sulphate mineral (calcium sulphate dihydrate) [15] and the oxidized form of sulphate minerals as pyrite (FeS 2 ) [16,17] is a natural source of high sulphate concentration. When metal sulphide (FeS 2 ) is exposed to atmosphere, it produces sulphate rich and acidic effluents (Eq. ...
Sulphate (SO4²⁻) is a common anion nutrient naturally occurs in water bodies, and considered not toxic when presented in low concentration. However, the presence of large amounts of SO4²⁻ induces sour taste in household water and scaling in pipe lines. A concentration of 500 to 750 mg(SO4²⁻)/L causes laxative effect, dehydration, and gastrointestinal irritation in human bodies. Hence, strict limitation was imposed on SO4²⁻ discharge, to conform with regulatory bodies standards. Several techniques were developed to eliminate or minimize the SO4²⁻ content in wastewater discharges. Generally, chemical precipitation method widely utilized for SO4²⁻ mitigation from high SO4²⁻ concentration sources particularly mine wastewater. However, the drawback of this process is that the theoretically obtainable minimum sulphate concentration with lime precipitation is 1500 mg/L SO4²⁻ at ambient temperature due to high solubility of gypsum. In the present review, the traditional and recently developed sulphate removal techniques are discussed by addressing their merits/drawbacks and potential further improvements. Moreover, novel integrated system which combines one or more advanced techniques in parallel with the established methods are reviewed that could pave the way towards the development of suitable technology. Finally, the life cycle assessment and techno-economic analysis are discussed for the various technologies.
Gold-bearing sulfide-quartz veins cutting mainly through the Atalla monzogranite intrusion in the Eastern Desert of Egypt are controlled by subparallel NE-trending brittle shear zones. These veins are associated with pervasive sericite-altered, silicified, and ferruginated rocks. The hosting shear zones are presumed as high-order structures of the Najd-style faults in the Central Eastern Desert (~ 615–585 Ma). Ore minerals include an early pyrite-arsenopyrite (±pyrrhotite) mineralization, partly replaced by a late pyrite-galena-sphalerite-chalcopyrite (±gold/electrum ± tetrahedrite ± hessite) assemblage. Gold occurs as small inclusions in pyrite and arsenopyrite, or more commonly as intergrowths with galena and sphalerite/tetrahedrite in microfractures. Arsenopyrite geothermometry suggests formation of the early Fe-As-sulfide mineralization at 380–340 °C, while conditions of deposition of the late base metal-gold assemblage are assumed to be below 300 °C. Rare hessite, electrum, and Bi-galena are associated with sphalerite and gold in the late assemblage. The early and late sulfide minerals show consistently a narrow range of δ³⁴S ‰ (3.4–6.5) that overlaps with sulfur isotopic values in ophiolitic rocks.
The Au-quartz veins are characterized by abundant CO2 and H2O ± CO2 ± NaCl inclusions, where three-dimensional clusters of inclusions show variable aqueous/carbonic proportions and broad range of total (bimodal) homogenization temperatures. Heterogeneous entrapment of immiscible fluids is interpreted to be caused by unmixing of an originally homogenous, low salinity (~ 2 eq. mass % NaCl) aqueous-carbonic fluid, during transition from lithostatic to hydrostatic conditions. Gold deposition occurred generally under mesothermal conditions, i.e., 1.3 kbar and ~ 280 °C, and continued during system cooling to < 200 °C and pressure decrease to ~ 0.1 kbar.
Based on the vein textures, sulfur isotope values, composition of ore fluids, and conditions of ore formation, we suggest that the Atalla monzogranite intrusion acted only as a competent structural host for ore deposition from shear-related, metal-rich fluids migrated up from depth. This model is also presumed for most granitoid-associated Au deposits in the region, considering the similarity in their structural control, alteration pattern and mineralogy, and chemistry of the ore fluids.
Remobilization of gold from a chalcopyrite-pyrite mineralization Hamash gold mine, Southeastern Desert
- H M Helmy
- R Kaindl
- M E Hilmy
- A Osman
- B Zoheir
- F Deshesh
- C Broman
- I Pitcairn
- A El-Metwally
- S Mashaal
Helmy, H. M., & Kaindl, R. (1999). Mineralogy and fluid inclusion studies of the Au-Cu quartz veins in
the Hamash area, South-Eastern Desert, Egypt. Mineralogy and Petrology, 65(1-2), 69-86.; Hilmy, M.
E., & Osman, A. (1989). Remobilization of gold from a chalcopyrite-pyrite mineralization Hamash gold
mine, Southeastern Desert, Egypt. Mineralium Deposita, 24(4), 244-249.; Zoheir, B., Deshesh, F.,
Broman, C., Pitcairn, I., El-Metwally, A., & Mashaal, S. (2018). Granitoid-associated gold
mineralization in Egypt: a case study from the Atalla mine. Mineralium Deposita, 53(5), 701-720.