applied sciences Article The Archaeometallurgical Evaluation of Three Bronze Socketed Axes, Discovered in Eastern Romania Viorica Vasilache 1 , Vasile Diaconu 2, Otilia Mircea 3, Ana Drob 1,4,* and Ion Sandu 5,6,* 1 ARHEOINVEST Center, Interdisciplinary Sciences Department, Institute of Interdisciplinary Research, “Alexandru Ioan Cuza” University of Ias, i, Bld Carol I no. 11, 700505 Ias, i, Romania; [email protected] 2 Museum of History and Ethnography Târgu Neamt, , Neamt, National Museum Complex, 37 S, tefan cel Mare Str., 615200 Târgu Neamt, , Romania; [email protected] 3 Museum of History Roman, Neamt, National Museum Complex, 16 Cuza Vodă Str., 611008 Roman, Romania; [email protected] 4 Faculty of History, Doctoral School of History, “Alexandru Ioan Cuza” University of Ias, i, Bld Carol I no. 11, 700505 Ias, i, Romania 5 Romanian Inventors Forum, Str. Sf. P. Movila 3, 700089 Iasi, Romania 6 Academy of Romanian Scientists (AOSR), 54 Splaiul Independentei St., Sect. 5, 050094 Bucharest, Romania * Correspondence: [email protected] (A.D.); [email protected] (I.S.) Abstract: This paper presents the study of three bronze socketed axes discovered in Neam¸tCounty, Romania. The surface structures and those from the interface of the corrosion layer with the metal core of the basic alloy were analyzed, in order to elucidate the nature of the materials used and the manufacturing processes. The analyzes by optical microscopy (OM) and electron microscopy (SEM), coupled with X-ray spectrometry (EDX), revealed the type of their degradation during the depositional period, as a result of the processes of chemical alteration and physical damage. A series of metallurgical techniques used were also established, as well as the identification of some finishing and decoration processes that led to the establishment of the objects’ functionality. Citation: Vasilache, V.; Diaconu, V.; Mircea, O.; Drob, A.; Sandu, I. The Keywords: OM; SEM-EDX; socketed axes; bronze; corrosion Archaeometallurgical Evaluation of Three Bronze Socketed Axes, Discovered in Eastern Romania. Appl. Sci. 2021, 11, 1811. https://doi.org/ 1. Introduction 10.3390/app11041811 Researchers in the field of scientific conservation of cultural heritage pay special attention to each archaeological discovery, and in the case of an archaeological artefact, Academic Editor: Karl Ulrich Kainer first and foremost is considered the context of the discovery, but also other aspects, such as Received: 21 January 2021 its manufacture, use and disposal. The context of the discovery provides a series of very Accepted: 16 February 2021 important data in determining the patrimonial features and functions of the artifact [1]. Published: 18 February 2021 The evolution of the conservation state is strongly influenced by the depositional period in the archaeological site. From the beginning, the primary patina is formed. It is Publisher’s Note: MDPI stays neutral based on chemical redox processes (oxides, sulfides, etc.), when continuous and uniform with regard to jurisdictional claims in published maps and institutional affil- films are formed. Due to these layers with their preservative role, it is also called the noble iations. patina. Before the abandonment and immediately after (the final phase of the period of use and continuing with the incipient phase after the abandonment), the secondary patina, also called poor patina, is reformed over the noble one. It occurs due to the aggression of the exogenous factors, when as a result of redox electrochemical processes, assisted by acido- basic, ionic exchange and hydrolysis processes, the following are formed: oxyhydroxides, Copyright: © 2021 by the authors. hydroxy salts, halogenates, carbonates, sulfates, phosphates, etc., which may be anhydrous Licensee MDPI, Basel, Switzerland. or hydrated in the form of crusts, nodes and moles, concentrated in or differentiated This article is an open access article across certain areas. For certain artifacts, in this phase they may suffer thermal effects distributed under the terms and conditions of the Creative Commons (calcination, recrystallization, etc.) following incineration and anthropic or natural fires. In Attribution (CC BY) license (https:// the archaeological site, over the secondary patina, tertiary or contamination patina forms, creativecommons.org/licenses/by/ under the influence of pedological, chemical and microbiological processes (segregation, 4.0/). diffusion, osmosis, monolithization, fossilization, mineralization, hydration/dehydration, Appl. Sci. 2021, 11, 1811. https://doi.org/10.3390/app11041811 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 1811 2 of 12 structural reforming, etc.). The three types of structures are often difficult to identify, on artifacts from both disturbed and undisturbed sites, due to variable/oscillating aggression of exogenous factors [2–17]. It is known that the authentication of an artifact means much more than dating and identifying the metal worker and the place of manufacture. In fact, attention is paid to a number of attributes related to the origin of the raw material, the elaboration of the basic material, the manufacturing technology, the craftsman/workshop, the owner/holder, the distribution area, the way of use and the course taken until the abandonment. These aspects contribute to the determination of patrimonial elements and functions. The old collections of some museums are composed from a series of objects that deserve a revaluation and a proper scientific valorification through modern methods, as is the case of the three socketed axes discovered in Neamt, County, Romania. These objects represent single finds, accidental discoveries without a clear context; but, as far as the metal objects are rare presences, these can be reevaluated and exploited from a scientific point of view through interdisciplinary methods, in order to gain more data. These axes were analyzed using noninvasive OM and SEM-EDX techniques to evaluate their archaeometallurgical characteristics, based on the chemical composition, the morphology of the corrosion crusts and the basic alloy. The experimental data allowed to indicate the artistic techniques and the manufacturing technology involved. The analogies of the pieces and their chronological frame indicate different cultural frameworks in three consecutive historical periods, so the main objective of this paper is to try to identify the manufacturing techniques that were used in order to follow the evolution and changes of these technologies in time in this specific area. Another objective is to investigate the depositional environment of the artifacts and its impact on their preservation trough the study of corrosion products and patina to find optimal conservation solutions. 2. Materials and Methods 2.1. Description of the Artifacts The three bronze socketed axes (Figure1) analyzed were selected from the collections of the History and Ethnography Museum in Târgu Neam¸t,presenting specific differences in shape, size, ornamentation and site aggression/conservation status. The artifacts were discovered in the eastern part of Romania, namely in the sub-Carpathian area of Neamt, county (Figure2), a rich area in salt springs (brine) that attracted prehistoric communities, exploiting the area’s resources since the Chalcolithic and which continue to be processed even today [18–21]. Thus, these bronze artifacts could represent goods obtained after the exchange with salt and may indicate a chief that oversaw and protected the area and the resources. Even if these objects represent accidental discoveries, without a clear context, the archaeometallurgical study could lead to new information about their use and symbolism. Appl. Sci. 2021, 11, 1811 3 of 12 Appl.Appl. Sci. Sci. 20 2120,21 11, ,11 x ,FOR x FOR PEER PEER REVIEW REVIEW 3 of3 of12 12 FigureFigureFigure 1. 1.1.Images ImagesImages of ofthe of thethe three three three socketed socketed socketed axes axes axes and and andthe the analyzed the analyzed analyzed areas areas areas(A ()A inventory) (inventoryA) inventory no. no. 4649 4649 no. (B 4649()B in-) in- (B) ventoryinventoryventory no. no. no.2113, 2113, 2113, (C ()C (inventoryC) )inventory inventory no. no. no.4650 4650 4650.. Figure 2. Geographic location of the discoveries, Neamţ county, Romania: A and C—Ţibucani; FigureFigure 2. 2.Geographic Geographic location location of of the the discoveries, discoveries, Neam¸tcounty, Neamţ county Romania:, RomaniaA:and A andC— C ¸Tibucani;—Ţibucani;B—Tg. B—Tg. Neamţ (Google Earth 2020). Neam¸t(GoogleB—Tg. Neamţ (Google Earth 2020). Earth 2020). SocketedSocketedSocketed axe axe axe A A A(Fig (Figure (Figureure1 1A)A), 1A), inventory inventory, inventory no. no. no. 4649, 4649, 4649, was was was discovered discovered discovered in 1965in in 1965 on1965 theon on territorythe the ter- ter- ritoryofritory ¸Tibucani, of of Ţibucani, Ţibucani, Neam¸tCounty, Neamţ Neamţ County, County, Romania. Romania. Romania. The pieceThe The piece was piece discoveredwas was discovered discovered on the on on bank the the bank of bank a creek,of of a a creek,withincreek, within awithin settlement a settlementa settlement of the of Noua of the the CultureNoua Noua Culture [Culture22,23]. [22, The[22,23].23]. piece The The has piece piece a length has has a oflengtha length 124 mm,of of 124 0.413124 mm, mm, kg 0.413weight,0.413 kg kg weight, a bladeweight, widtha ablade blade of width 45 width mm, of theof45 45 depthmm, mm, the ofthe thedepth depth fixing of of the orifice the fixing fixing is