Zsolt Kasztovszky

Prompt Gamma Activation Analysis, a new method in the archaeological study of polished stone tools and their raw materials

Metabasic rocks, particularly greenschists, were very popular raw materials for making polished stone tools by prehistoric man in the Carpathian Basin. The major and trace element compositions of these objects are very helpful in determining the place of origin of the rocks. On the other hand, destruction of the complete object is usually not allowed during the analysis. In this paper we show an application of Prompt Gamma Activation Analyses (PGAA), a relatively new, non-destructive method for investigation of Neolithic stone tools. Twenty-four samples (in the form of greenschist and blueschist polished stone tools from Hungarian Neolithic collections and also greenschists and blueschist from outcrops) were investigated. The aim of this work was to establish a method for distinguishing the different types of greenschists occurring in the Carpathian Basin. PGAA gives reliable data for major and some trace elements of geochemical interest. According to our results, it is possible to distinguish blueschist from macroscopically similar greenschist polished stone tools by PGAA. Three macroscopically different types of greenschist samples form only two groups according to chemical composition, which implies only two different sources of greenschist raw material. We were able to identify one of them as rock from the outcrop of Felsocsatar (Penninic Unit of the Alps in western Hungary). The second source is not yet determined; it requires the study of samples from more outcrops. The investigation of ancient stone tools is only one example of the applicability of PGAA. The advantages of this method can also be exploited in other geochemical research areas.

Discrimination of prehistoric polished stone tools from Hungary with non-destructive chemical Prompt Gamma Activation Analyses (PGAA)

The determination of the geological provenance of the different rocks employed for the manufacture of prehistoric stone tools is useful from both historical and archaeological points of views, to indicate precise directions of cultural interactions. Prehistoric polished stone tools with fine to very fine grained texture may show striking similarities in their macroscopic appearance by texture and colour. Therefore, it is very difficult to distinguish the different rock types by naked eye. Prompt Gamma Activation Analysis (PGAA) is one of the powerful, absolutely non-destructive bulk chemical methods for the analysis of archaeological materials. As regards polished stone tools, PGAA measures all major elements and few trace elements. We analyzed 189 polished stone tools from different collections and localities of Hungary, and 42 geological samples from potential raw material sources. To control the method, several broken pieces were studied also by destructive methods, mainly thin-section petrography. Our results are: 1. we obtained chemical composition of the analyzed artefacts, 2. we created an initial database of PGAA results of the most important raw materials of polished stone tools occurring in Hungary, 3. we explored the potentials and limitations of PGAA in the determination of the raw materials used for the polished stone tools. As a result, several different raw material groups (basalt-dolerite-metadolerite, greenschist-contact metabasite-amphibolite, blueschist, hornfels, “white stone”, ultramafic rocks and intermediate volcanic rocks) could be distinguished. Moreover, different rock types were recognized within each group ( e.g ., greenschist-contact metabasite and basalt-dolerite). Macroscopic description combined with PGAA will help to determine raw material types of polished stone tools. However, in some cases other methods are also necessary to achieve precise determination.

The use of neutron analysis techniques for detecting the concentration and distribution of chloride ions in archaeological iron

Chloride (Cl) ions diffuse into iron objects during burial and drive corrosion after excavation. Located under corrosion layers, Cl is inaccessible to many analytical techniques. Neutron analysis offers non-destructive avenues for determining Cl content and distribution in objects. A pilot study used prompt gamma activation analysis (PGAA) and prompt gamma activation imaging (PGAI) to analyse the bulk concentration and longitudinal distribution of Cl in archaeological iron objects. This correlated with the object corrosion rate measured by oxygen consumption, and compared well with Cl measurement using a specific ion meter. High-Cl areas were linked with visible damage to the corrosion layers and attack of the iron core. Neutron techniques have significant advantages in the analysis of archaeological metals, including penetration depth and low detection limits.

Applications of PGAA with Neutron Beams

This chapter details applications of reactor-based neutron capture prompt gamma-ray activation analysis (PGAA). Most of the applications discussed were performed by using thermal and cold (subthermal) neutron beam facilities. PGAA with internal sample placement (e.g. in a thermal column or reactor channel) is also discussed because similar or identical analytical applications could be carried out with neutron beam irradiations. In-beam PGAA has fewer sample matrix and size restrictions but has some disadvantages, such as, for thermal neutron PGAA (TPGAA), element sensitivity variability caused by neutron elastic scattering, primarily by H (Anderson et al. 1985, Mackey et al. 1991), and, for subthermal (or “cold”) neutron PGAA (SPGAA), sensitivity variations caused by neutron energy increase in room-temperature matrices. Low neutron fluxes (typically 106 to 109 cm−2 s−1) and, therefore, low residual radioactivity, associated with in-beam PGAA make possible rapid follow-up analysis of the same analytical portions with other techniques, such as ion chromatography (IC), inductively coupled plasma-atomic absorption spectrometry (ICP-AES), or instrumental neutron activation analysis (INAA).

Non-invasive PGAA, PIXE and ToF-ND analyses on Hungarian Bronze Age defensive armour

Non-invasive, archaeometric analyses on selected Hungarian Bronze Age defensive armour is presented here: three greaves, three helmets two shields as well as one vessel fragment were analysed with PIXE, PGAA and TOF-ND. The detected alloy elemental and phase composition as well as its intergranular or spatial concentration distribution reveals important insights into the alloys used and the manufacturing techniques applied c. 1200–950 BC, and allows to reconstruct the production techniques used during the Late Bronze Age.

Size effects in micro- And nanocarbon added C/Si3N4 composite prepared by hot pressing

Silicon nitride based composites have been fabricated by carbon addition. Carbon black nanograins and graphite micrograins were used as second phase additions. Alumina and yttria were used as sintering aids. Mixing of powders was performed in a ball mill and for comparison in a high efficient attritor mill. For sintering the hot pressing technique has been applied. Experiments at 2 MPa uniaxial pressure have been performed. The Si/N mass fraction after sintering were determined by prompt gamma activation analysis (PGAA). The amount of carbon black and graphite introduced in the silicon nitride matrix increased the porosity and decreased the hardness and bending strength of composites. Lower modulus, and lower strength was obtained for composites with carbon black addition in comparison to graphite added samples. The microstructure of composites consisted mainly of alpha and beta silicon nitride. The formation of silicon carbide was observed only at 10 wt% carbon black addition.

Ceramics, Marbles and Stones in the Light of Neutrons: Characterization by Various Neutron Methods

In this chapter we give a brief overview of neutron based analytical investigations applied to study archaeological ceramics, and different types of stones. Since the vast majority of archaeological objects are made of ceramics and various stones—all are of geological origin—, one of the key objectives of these studies to determine the origin of raw material. This research is called provenance research, and a wide range of neutron based methods are applicable in it. Following a very basic, user-oriented description of the methods, we introduce examples from our everyday practice. The examples are about provenance of prehistoric stone tools, about the sources of 4th–3rd c. B.C. millennium limestone idols found in the South of Portugal, as well as about the characterization of 15th–16th c. A.D. Inka pottery. A very unique application of combined neutron techniques was aimed to determine the inner content of an Eighteenth Dynasty Egyptian sealed vessel. In addition, investigations of samples from different epochs and characterization of marbles are presented.

High pressure metaophiolite polished stone implements found in Hungary

Good quality high pressure (HP) metaophiolite rock types (e.g. Na-pyroxenite/jade, eclogite) suitable for making prehistoric polished stone implements were unknown among Hungarian findings for a long time. Nowadays they are still among the rarest types of polished stone implements found in Hungary in the respect of raw material. After the first discovery of Neolithic stone tools made of HP metaophiolites in the records of Hungarian archaeological assemblages, detailed petrological investigations of large stone implement collections revealed their presence in a relatively large number. According to our current knowledge, 25 HP metaophiolite stone implements are known as found in Hungary. Unfortunately, most of them are stray finds, but 11 pieces from four localities have a known archaeological context. They were mainly located in Transdanubia (except for one piece from Tiszántúl) and are mostly attributable to the Late Neolithic Lengyel Culture and secondarily to the Late Neolithic Tisza Culture. In this study, we used only non-destructive analytical methods (macroscopic observation, magnetic susceptibility measurements, non-destructive SEM-EDX, and Prompt Gamma Activation Analysis). As a result of this study, the prehistoric stone implements were classified into raw material types. Based on our data, the high pressure-low temperature (HP-LT) metaophiolite stone implements found in Hungary probably originated from the same raw material sources as the Italian HP-LT metaophiolite stone tools (sourcing from North-western Italy). According to the literature on the topic, both primary (Western Alps in the vicinity of the Monviso in Piedmont or the Voltri Massif in Liguria) and secondary occurrences (in Quaternary deposits of the rivers Po, Staffora and Curone) are potential sources. These analyses confirmed the existence of long-distance trade routes connecting the Po Valley and its vicinity with the Carpathian Basin during the Vth Millennium BC.

X-ray and neutron-based non-invasive analysis of prehistoric stone artefacts: a contribution to understand mobility and interaction networks

Carbonate-rich archaeological artefacts are difficult to identify and correlate between them and with raw materials of such heterogeneous geological sources, especially when only non-invasive analysis is possible. A novel combination of X-ray and neutron-based non-invasive analysis is implemented and used for the first time to study prehistoric stone idols and vessels, contributing to culture identity, mobility and interaction in the recent Prehistory of Southern Iberia. Elemental composition was obtained by prompt gamma activation analysis (PGAA) and external beam particle-induced x-ray emission (PIXE); homogeneity of the stone artefacts and the presence/absence of internal fractures were obtained by neutron radiography (NR). These atomic and nuclear techniques, simultaneously used for complementary chemical information, have been demonstrated to be of great value as they provide non-destructive compositional information avoiding sample preparation, crucial in so singular and rare objects. The obtained results, especially of PGAA, are very promising and useful in general assessments of provenance. The stone artefacts show signs of both nearby and long-distance procurement, as well as of unknown attribution.