# Study on the Middle Bronze Age Disc-Butted Axe Ornament from Archaeometallurgical Point of View
## 1 Introduction  
From an archaeometallurgical point of view, Bronze Age copper alloys may be classified as follows [1, 2, 3, 4, 5]:  
* copper derived from nuggets, with traces of microelements of the same base ore;
* semi-bronzes, with alloying elements derived from two or more copper ones, different in terms of chemical composition;
* bronzes made of base metal (copper) and alloying elements in the form of ingots (tin, zinc, lead, nickel, iron, arsenic and antimony), obtained separately from copper ones and from ores rich in tin, zinc, lead etc. Compared to gold and silver, bronzes are harder, but they are less eye catching. Therefore, ancient bronze artefacts (tools, weapons, vessels, mirrors, etc.) were either polished/gilded or ornamented on the surface. Ornamentation was performed by several ancient handicraft processes:  
* chiselling and encrustation of the surface of the object [3; 6];
* tinning (initially by rubbing with tin ores reduced with charcoal at temperatures much lower than the bronze melting temperatures, as later by immersion in molten tin) [3; 7; 8; 9; 10];
* silvering and gilding by polishing [11; 12; 13; 14]. In the case of the last two surface filming processes, ornamentation was performed either before or after polishing or tinning. The archaeometallurgical study of the ornamentation of some objects by tinning on the whole surface showed that the decoration most likely was made after tinning, as the thin surface tin film allows fine inlay of bone needles, hardwood or even bronze) [3]. It is a known fact that, both during their use and during their lying in the ground, ancient bronze artefacts suffered degradation effects (segregation of more active metals to the surface and change of chemical nature by surface corrosion processes), often accompanied, before abandonment, by thermal processes such as incineration or burning. They also suffered structural-functional deterioration effects, due to wear and pedological processes of erosion [15; 16; 17; 18; 19; 20; 21]. Depending on the composition of the alloy and the degree of wear before abandonment, the two effects trigger usually irreversible changes both in the structure and in the morphology of the artefact, which loses its shape and hence its historical significance [22; 23; 24; 25; 26]. If, on discovery, the artefact is in a good state of preservation, it is easy to reveal in its composition the main alloying elements and morphological features of the phases and structural manufacture constituents. These allow the identification of archaeometric features used in authentication. Based on the composition, layout and shape of the structural components, the archaeometallurgical process of alloy obtaining and the manufacture of the artefact (hence of the ornament) may be assessed, and the routes travelled by the artefact from its commissioning to its discovery may be identified [20; 21; 23; 24; 27]. Among the copper and bronze pieces, ornamented disc-butted axes are valuable artefacts, due to the uniqueness of their shape and decoration, and to the complexity of their manufacturing technology [3; 6; 28; 29; 30]. This reveals the skill of the ancient craftsmen in making such artefacts by selecting the raw materials and the processes of casting and ornamentation (archaeometallurgy) [3; 6; 17; 24; 27; 31; 32; 33; 34; 35]. After the publication of recent research by the authors [3; 6; 7; 8; 9; 10; 20; 21; 36; 37; 38; 39; 40], a number of archaeologists commented on the ornament, that it was not an archaeo-pyrometallurgical process, but rather the Liesegang effect. (Of course, being not a specialist in chemistry or metallurgy, is hard to deepen either of the two processes). Then the problem was to elaborate a semi-quantitative, non-invasive study, involving a modern and pervasive SEM-EDX technique, which would allow, by correlating with the data recently published, the profile of the arrangement of chemical components on the surface and the interface, but also in the stratigraphic structure of the ornament.