CHARACTERIZATION OF PACIFIC NORTHWEST COAST OBSIDIAN BY X-RAY FLUORESCENCE ANALYSIS

Several geological sources of obsidian in the Pacific Northwest have been characterized by means of their trace element concentrations, as measured by X-ray fluorescence analysis. The technique is fast and completely non-destructive, making it well-suited for identifying the sources of obsidian from which artifacts were fabricated.     

TEMPORAL ORDERING OF SURFACE-COLLECTED OBSIDIAN ARTIFACTS BY HYDRATION MEASUREMENT

Two samples of obsidian projectile points from northwestern Nevada, one surface collected and the other excavated, were subjected to obsidian hydration measurement. The temporal ordering of the three projectile-point types in each of the two samples was demonstrated to be the same on the basis of their hydration measurements. The validity of this temporal ordering of the projectile-point types in the two samples was confirmed by the stratigraphic sequence of the types in the excavated sample. We have found that surface-collected obsidian artifacts can be relatively dated by hydration measurement. In northwestern Nevada they hydrate at a rate almost double that of their excavated typological counterparts, but their relative ordering remains the same.     

NON‐DESTRUCTIVE SOURCING OF BRONZE AGE NEAR EASTERN OBSIDIAN ARTEFACTS: REDEVELOPING AND REASSESSING ELECTRON MICROPROBE ANALYSIS FOR OBSIDIAN SOURCING*

Despite predictions in the 1980s that electron microprobe analysis (EMPA) would become a popular technique for obsidian sourcing, few studies have used it with this goal, and most of them are now outdated and unrepresentative of modern EMPA. For example, Merrick and Brown (1984 ) recorded their data on punch cards. Furthermore, these studies destructively prepared artefacts for analysis. The research at hand endeavoured: (1) to establish the modern capabilities of EMPA for obsidian sourcing; and (2) to develop and evaluate procedures for non‐destructive artefact analysis. Issues such as diagenetic effects and compatibility with NAA and XRF data were also investigated.     

ANALYSIS OF COPPER-BASED METALLIC ARTIFACTS BY PROMPT GAMMA-RAY NEUTRON ACTIVATION ANALYSIS

Non-destructive analysis of the major elements in copper-alloyed artifacts by prompt gamma neutron activation analysis is reported. Copper, zinc, tin and lead were measured in several ancient Roman, Greek and Iranian objects. Good agreement was found in comparison with analysis of similar objects by destructive methods.     

APPLICATIONS OF PETROGRAPHY AND ELECTRON MICROPROBE ANALYSIS TO THE STUDY OF INDIAN STONE SCULPTURE*

Examples of research on ancient Indian stone artefacts utilizing petrographic examination coupled with qualitative and quantitative electron beam microprobe analysis of specific minerals are described. Types of artefacts discussed include Gandharan schist sculptures. Pala dynasty phyllite and schist objects from eastern India, Hoysala sculptures from Karnataka state (southern India), and sandstone objects from northern India. In spite of the rich history of stone sculpture in the Indian subcontinent, characterization studies to date have been limited in scope, typically involving unprovenanced artefacts. The examples described point to areas in which more extensive research could produce useful information for the provenancing of artefacts.     

CHARACTERIZATION OF SAMIAN WARE SHERDS BY MEANS OF NEUTRON ACTIVATION ANALYSIS

Neutron activation analysis has been employed for the characterization of Samian ware sherds. The analysed samples were classified in ten groups, seven of which belonged to the Arretine production, according to archaeological evidence. By means of high resolution gamma-ray spectroscopy, 22 elements have been identified and analysed. Compositional characterization was looked for by taking counting rate ratios of different nuclides in the samples. The compositional pattern of the sherds was found to be fairly uniform both for each pot and for each group so that, at least in the examined cases, it can be assumed to be characteristic of a given workshop.     

NO STONE UNBURNED: A COMPOSITIONAL ANALYSIS OF OBSIDIAN MICRODEBITAGE BY LASER ABLATION TOF–ICP–MS

Obsidian is an effective material for the study of prehistoric raw material use and exchange, due to the high degree of homogeneity and redundancy of obsidian materials and manufactured objects in the archaeological record. The destructive nature of many analytical techniques often impedes compositional research because of the damage that may occur to priceless archaeological artefacts. The combination of time‐of‐flight (TOF) ICP–MS with a laser ablation sample introduction system provides a highly efficient means of chemically characterizing obsidian. This study shows that sample size limit capabilities of TOF–ICP–MS analysis of obsidian can reach less than 100 μm. Sampling and analysis of microartefacts enables researchers to overcome problems of sampling bias with very little damage to the valuable existing materials within the archaeological record and expands the potential for chemical compositional analyses in archaeology.     

PHYSICO‐CHEMICAL CHARACTERIZATION OF THE ACQUALADRONE ROSTRUM

The archaeological discovery of the Acqualadrone rostrum (an offensive naval weapon mounted on the prow at the waterline), off the Italian coast near Messina in 2008, has led to the need for scientific research in order to plan the conservation treatment of this artefact. The discovery is exceptional because of the presence of a wooden section from the original ship. This paper describes the physico‐chemical characterization of a metallic and two wooden samples by inductively coupled plasma – optical emission spectroscopy, inductively coupled plasma – mass spectrometry, Fourier transform infrared spectroscopy, ¹³C {¹H} cross‐polarization magic angle spinning NMR spectroscopy, energy‐dispersive X‐ray spectroscopy, gas chromatography – mass spectrometry and X‐ray diffraction. The results reveal the use of leaded bronze (Cu, 70%; Pb, 20%; Sn, 10%) in the manufacturing process of the alloy and the use of lead whose isotopic composition is referable to either Spanish or Cypriot mines. The analysis of the results relating to the wooden samples indicates their different state of preservation and, at least in some places, the spreading of caulking on the wood, probably using a vegetable resin.     

A COMPARATIVE ELECTRON MICROPROBE STUDY OF LERNA III AND IV CERAMICS AND LOCAL CLAY-RICH SEDIMENTS*

This study uses electron microprobe analysis of ceramic artefacts and local day-rich sediments and lithics to help address questions concerning the nature of the cultural change implied by ceramics from Lerna III and IV. It redresses the previous lack of a comparative collection of clay-rich sediments that adequately represents the local variation in clay and temper for the area surrounding Lerna. The resulting comparisons indicate that although they produced stylistically different ceramics, potters from both Lenta phases acquired their clays from the local Lerna area.     

NON-DESTRUCTIVE ANALYSIS OF OBSIDIAN ARTEFACTS USING NUCLEAR TECHNIQUES: INVESTIGATION OF PROVENANCE OF NEAR EASTERN ARTEFACTS

A non-destructive analytical method using both instrumental neutron activation and proton-induced gamma ray emission techniques was developed to study the provenance of obsidian artefacts from Turkey, Syria and Iraq.     

MOESSBAUER SPECTROSCOPIC,CHEMICAL AND MINERALOGICAL CHARACTERIZATION OF IBERIAN POTTERY

Three types of Iberian pottery from the same excavation and archaeological level have been studied by Moessbauer spectroscopy, atomic absorption spectroscopy, X-ray diffraction, and transmitted-light polarizing microscopy. The results are compatible with a common origin, a firing temperature below 850 °C, and a different fabrication technique for each pottery type.     

CHEMICAL CHARACTERIZATION AND STATISTICAL MULTIVARIATE ANALYSIS OF ANCIENT POTTERY FROM MESSINA,CATANIA, LENTINI AND SIRACUSA (SICILY)*

This paper presents the chemical characterization of 79 fragments of Archaic and Hellenistic fine‐grained pottery from archaeological sites in Messina, Catania, Lentini and Siracusa (Sicily). The sherds were classified as ‘calcidian’, ‘banded’, ‘unvarnished’ and ‘black varnished’ pottery. The major and trace elements identified by X‐ray fluorescence (XRF) were statistically elaborated using the method proposed by J. Aitchinson in 1986 for the analysis of compositional data. From cluster analyses using element/SiO₂ log‐ratios, it was possible to group the pottery found in Catania, Lentini and Siracusa into highly linked clusters. Conversely, the Messina pottery was divided into two clearly distinct groups. With the aim of identifying any possible mineralogical differences between the two Messina groups, Fourier transform infrared (FT–IR) absorption measurements were made, showing only quantitative differences in plagioclase and muscovite. The specific groups of pottery with restricted chemical compositions are considered to be of local production, also on the basis of archaeological and petrographic evidence.