Archaeometallurgical characterization of Greco-Roman copper-based and iron nails from Tel Abu Seify, North Sinai, Egypt

The current study focuses on the investigation of a collection of copper alloy and iron nails discovered amid numerous metal artifacts in the archaeological excavations of Tel Abu Seify, North Sinai, Egypt. This site, identified as a shipbuilding and repair facility, dates back to the Greco-Roman era (Circa 332BCE–A.D. 641). Different analytical methods were employed to ascertain the composition of the alloys, manufacturing techniques, and characteristics of the corrosion products in the nails. A range of techniques were utilized to achieve this goal, including optical and metallographic microscopy, X-ray radiography, portable X-ray fluorescence, SEM-EDS, micro-Raman spectroscopy, and X-ray diffraction. The results indicated that 19 of the examined nails were composed of copper alloy, except for two nails made of iron. The analysis revealed that the tin bronze nails were predominantly composed of copper, with a minor presence of tin (4.3 wt%), lead (4.7 wt%), and traces of iron and arsenic. Additionally, the iron nails were made of low-carbon iron alloys. Microscopic examination indicated that the nails were manufactured via cold hammering. The patina observed on the copper nails encompassed cuprite, atacamite, clinoatacamite, antlerite, and cerussite, often interspersed with the soil residues. The rust surfaces of the iron nails comprised hematite, magnetite, goethite, akaganeite, and lepidocrocite. The iron nails and some copper nails exhibited partial or total mineralization, whereas most copper nails remained in good condition, generally retaining their metallic cores.