Analysis of the Quintilii’s Villa Bronzes by Spectroscopy Techniques

Abstract

The aim of this work is the characterization, with different diagnostic tests, of three fragments of bronze artefacts recovered from the Villa of the Quintilii (located in the south of Rome). In particular, the sample alloys were investigated by different chemical and morphological analysis. Firstly, an analysis of the alloy, implemented through the electronic spectroscopy, was taken to discriminate the bronze morphology and its elemental composition. Subsequently, a surface analysis was realized by molecular spectroscopy to identify the alteration patinas on surfaces (such as bronze disease). Two diagnostic techniques are used for the alloy analysis: scanning electron microscopy (SEM) connected to the EDX spectroscopy (to study the morphology and alloy composition) and Auger electron spectroscopy (AES) (to identify the oxidation state of each element). Moreover, for the study of surface patinas, IR and Raman spectroscopies were implemented. All studies were performed on the "as received" samples, covered by a thin layer of excavated soil and on samples processed in an aqueous solution of sulphuric acid (10%), to remove patinas and alterations.

Raman spectroscopy of green minerals and reaction products with an application in Cultural Heritage research

“…Connellite (Cu 36 (SO 4 )(OH) 62 Cl 8 · 6H 2 O) is recognizable by the bands at 984, 585, 446, 404, 350, 262, 236, 192, 184 (shoulder) and 132 cm −1 (Table ). As the mineral contains OH units, stretching bands are expected.…”

“…3550 cm −1 is observed (Figure S1, spectrum b). Its formation on copper containing artefacts can be described as bronze disease …”

“…Malachite is typically present in Cu ore deposits (Hungary, East Central Europe, France; Cyprus, Macedonia, Spain, Armenia), and it is often associated with azurite, chrysocolla and cuprite . Malachite is also found as a corrosion product on bronze …”

“…Antlerite (Cu 3 (SO 4 )(OH) 4 ), brochantite (Cu 4 (SO 4 )(OH) 6 ), posnjakite (Cu 4 (SO 4 )(OH) 6 · H 2 O) and langite (Cu 4 (SO 4 )(OH) 6 · 2H 2 O) are some of the most interesting basic copper sulphates from those points of view. Others are chalcantite (CuSO 4 · 5H 2 O), serpierite (Ca(Cu,Zn) 4 (OH) 6 (SO 4 ) 2 · 3H 2 O), connellite (Cu 36 (SO 4 )(OH) 62 Cl 8 · 6H 2 O) and chalcophyllite (Cu 18 Al 2 (AsO 4 ) 4 (SO 4 ) 3 (OH) 24 · 36H 2 O) …”