Old mining and smelting features in the Abu Gerida area have been studied using field observations, microscopy and SEM-EDS to detect the ores that were exploited in antiquity. There are two groups of shafts in the area. The first group encloses secondary copper minerals and is associated with glassy slags containing copper prills. The other group is associated with hematite that was extracted and transferred to a smelting station to the west of the mining site, where iron slags and charcoal fragments are found. These slags are composed mainly of wüstite, fayalite-kirschsteinite and traces of metallic iron. Pottery fragments from this area were dated to the Ptolemaic Period, which may be the age of iron exploitation. Copper might have been exploited earlier.
Corrosion is a predominant problem for the different materials. Various methods have been utilized to prevent this phenomenon; some routes have caused great environmental effects, and are harmful to humans. Recently, green corrosion inhibitors have been used to overcome this problem. This paper discusses the corrosion inhibition behavior of bronze in 3.5% NaCl solution in the absence and presence of Jatropha extract as a green corrosion inhibitor. Bronze coupons were made based on the chemical composition of cast bronze alloys used in archaeological artifacts. The influence of inhibitor concentration and operating temperature on the inhibition efficiency was studied using weight loss, electrochemical techniques, salt spray, and colorimetric measurements. The results showed that Jatropha extract could serve as an effective inhibitor in 3.5% NaCl. The inhibition efficiency (IE%) increases with an increase in inhibitor's concentration but decreases with temperature rise. The highest inhibition efficiency was 90.36 % at 30 ppm of Jatropha and at room temperature [~25 °C]. The inhibition is attributed to the physical adsorption of the inhibitor on the surface of the bronze alloy. Finally, based on the findings of this study, Jatropha extract is highly recommended for use as a green corrosion inhibitor for archaeological artifacts.
The importance of understanding the corrosion mechanisms of excavated metal artefacts help in determining the physico-chemical parameters of the burial environment and the formation of different corrosion products. These products can be observed and analysed with the help of various techniques that provide information on their morphology, chemical composition and structure. The analysis of ancient coins is extremely challenging in the presence of heavily corroded surfaces; as quantitative information may not exactly concur with its bulk composition. In the case of silver coins, the use of surface information can be used as a guide for bulk composition only. The current study carries out investigation and characterization of selected coins from a large coin hoard excavated from Amheida, Dakhla oasis, Egypt. The study and analysis of the alloy composition and corrosion products was performed using a multi-technique approach which included Light optical microscopes, Scanning Electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) and X-ray diffraction analysis. Investigation of the coins revealed the presence of a thick active inhomogeneous corrosion crust, while analysis showed that the coins were made from a binary silver copper alloy (billon) while the corrosion crust was rich in chlorides and carbonates, later identified by XRD analysis as Paratacamite, Malachite and Chrysocolla.
Several archaeological coins were discovered in Tell Timai, Elsembelawen, Daqahleya. They were heavily corroded and in a bad state of preservation. Different corrosion products mixed with soil encrustation totally obscured the surface. The present paper aims to identify the morphology and composition of the alloy and corrosion products, perform a condition assessment and determine the best methods for treatment. Therefore, an analytical and characterization study on coin samples was carried out using X-ray diffraction analysis and portable X-ray fluorescence to understand the nature and composition of the alloy and patina. The results indicated the deterioration of the coins. X-ray diffraction analysis showed that the corrosion layers were mostly composed of chlorides, sulfates, and carbonates with some soil residues of gypsum and other compounds. X-ray fluorescence results showed that the coins consisted of ternary alloy [copper, tin, and lead ].The composition of the coins indicated that several coins were high-leaded bronze, except one made from leaded copper. Finally, the results obtained help choose the best treatment and conservation methods. The conservation of the coins required removing the soiled deposits, encrustations, and corrosion layers covering the coins completely while preserving their integrity.
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