The occurrence of brochantite on archaeological bronzes: a case study from Lofkënd, Albania. (17th February 2018)

• Record Type: Journal Article
• Authors: Muros, Vanessa; Scott, David A.
• Is Part Of: Studies in conservation. Volume 63:Number 2(2018)
• Page Start: 113
• Page End: 125
• Publication Date: 2018-02-17
• Subjects: Bronze -- Albania -- late bronze age -- brochantite -- sulfate-reducing bacteria -- microbiologically induced corrosion -- metallography -- X-ray diffraction; Art objects -- Conservation and restoration -- Periodicals; 700.288
• DOI: 10.1080/00393630.2016.1264179
• Languages: English
• ISSNs: 0039-3630

Abstract

ABSTRACT: A technical study was conducted on a group of copper alloy artifacts excavated from the burial tumulus of Lofkënd (fourteenth–ninth century BCE) to identify the alloy compositions and methods of manufacture. The surface corrosion was also examined in order to understand the diagenetic processes affecting the preservation of the finds and their condition. Portable X-ray fluorescence spectroscopy, metallographic examination, and X-ray powder diffraction (XRD) analysis were used to characterize the alloy composition and identify the corrosion products present. XRD analysis showed the presence of brochantite (Cu4 SO4 (OH)6 ) on five of the metallic artifacts. Brochantite is not commonly reported on archaeological bronzes from terrestrial sites, but is more readily found on copper alloy objects exposed to sulfur pollutants in the air or soil. The possible conditions that could have led to the formation of this corrosion on the bronzes from Lofkënd are discussed in the context of the particular burial environment found at the tumulus. GRAPHICAL ABSTRACT: