Bracelet with dragonflies - Leaded Bronze - Late Bronze Age

Perret-Gentil. Emeline (HE-Arc, Neuchâtel, Neuchâtel, Switzerland)

Complementary information

No information on the archeological or historic context before 2008 (year of donation to the museum).

Before restoration the artefact was conserved in 3 parts and it was possible to observe a stratigraphy on the cross section.

The schematic representation below gives an overview of the corrosion layers encountered on the bracelet from a first visual macroscopic observation under binocular microscope.

 

Fig. 8 : Stratigraphic representation of the bracelet in cross-section using The MiCorr application, credit MiCorr_HE-Arc CR, E. Perret-Gentil

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Noting to report.

Analyses performed : SEM-EDS

The remaining is a porous leaded bronze with an high concentration of Sn et Pb (Table 1 and Fig. 12) . The result shows an important % of Pb but after discussion with the analyst, the % of Pb is more or less around 5%. The 9% is due to the analysis area which contains Pb nodules and false the result

Elements Cu Sn Pb
mass% 76 15-16 9

Table 1 : Chemical composition (mass %) of metal (Fig.9). Methode of analysis : SEM/EDS. Neode

Under DF microscope, we can observe dendritic structure (Fig.10) of an as-cast metal with Cu and Sn-rich phase (Fig. 11 : internal dendrite is more yellow and contain more Cu (A ; Fig. 13) and is surronded by an orange color with more Sn (B ; Fig. 14). Between the dendritic structure lead nodules are visible (C ; Fig. 15).

 

The results of the XRD analysis are useless.

Complementary information

Interdendritic corrosion are visible on the interface metal/corrosion product (Fig. 16) and Phantom dendrite are visible on corrosion product ().

Remettre stratigraphie -> ajouter ce que ça pourrait être

redire quel métal

Bibliography :

 

Scott, 1991 : Scott, David A. Metallography and Micrsotructure of Ancient and Historic Metals. Getty Publications, Los Angeles, 1991

 

Scott, 2002 : Scott, David A. Copper and bronze in Art : corrosion, colorants, conservation. Getty Publications, Los Angeles, 2002

Warangkhana, 1983 : Warangkhana, Rajpitak. The development of copper alloy metallurgy in Thaïland in the pre-buddhist period, with special reference to high-tin bronzes

 

 

 

White, 2008 : White, J.C. “Dating Early Bronze at Ban Chiang, Thailand”. In From Home erectus to the living traditions: Ühoice of Papers from the 11th International Conference of the European Association of Southeast Asian Archaeologists, Ûougon, 25th-29th September 2006, édité par Pautreau, J.-P, … [et al.], pp. 91-104.