STEATITE SOURCE CHARACTERIZATION IN EASTERN NORTH AMERICA: NEW RESULTS USING INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS*

Doubts have recently been cast on the ability to characterize steatite sources using rare earth elements (REEs). By increasing the number of samples and elements examined using instrumental neutron activation analysis (INAA) and multivariate statistics, this study shows that, with unhomogenized samples, transition metals, not REEs, make the greatest contribution in characterizing steatite sources in the Middle Atlantic region of eastern North America. Preliminary results suggest that INAA has the potential to assign provenance to steatite artefacts, at least at a regional level.     

THE SMITHSONIAN–NIST PARTNERSHIP: THE APPLICATION OF INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS TO ARCHAEOLOGY

The history and procedures of the Smithsonian–NIST programme in the application of instrumental neutron activation to the study of archaeological materials are reviewed. Statistical processing of the resulting analytical data is a major focus of the programme, with attention called to processes of initial group formation. Specific areas of current research emphasis are presented, which build upon the strength of accumulated databases.     

THE HISTORY OF THE LAWRENCE BERKELEY NATIONAL LABORATORY INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS PROGRAMME FOR ARCHAEOLOGICAL AND GEOLOGICAL MATERIALS

The Lawrence Berkeley National Laboratory pottery provenance group developed standards and instrumental neutron activation analysis (INAA) methods that are used at many archaeometry laboratories around the world. The background and development of ‘Standard Pottery’ and of methods for INAA are described. Early pottery provenance studies are described, and other research programmes, involving obsidian and magmatic mixing, the origin of the stone used for the Colossi of Memnon, and the ‘Plate of Brass’, are mentioned. Research work by the Laboratory included the discovery of the world‐wide iridium anomaly and extensive subsequent research on what has come to be known as the ‘Asteroid Impact Theory’. Characteristics of the analytical programme for pottery provenance work, including overall aims, precision and accuracy, intercalibration, and irradiation and measurement protocols, are discussed. New research areas developed in the past 15 years, to broaden the usefulness of chemical compositional data for archaeological investigation, and examples of recent work, are described. This research, which makes use of high‐precision X‐ray fluorescence analysis in addition to INAA measurements on sample splits, includes distinguishing the products of different workshops located at the same production site, studies on the significance of the distribution of silver in archaeological pottery and the use of high‐precision chemical compositional data as an aid for making chronological distinctions.     

NEUTRON ACTIVATION ANALYSIS OF PREHISTORIC FLINT MINE PRODUCTS

Specimens of flint from English and Continentai prehistoric factory/mine sites have been analysed using neutron activation and element compositions compared. The possible use of element concentration patterns as a means of characterising such sites is discussed.     

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.     

PERSPECTIVES ON THE DATING OF PREHISTORIC GREAT BASIN PETROGLYPHS BY NEUTRON ACTIVATION ANALYSIS

The possible relative dating of petroglyphs by nuclear measurements on desert varnish is explored. The abundances of 30 major and trace elements in desert varnish samples from the Grimes Point petroglyph site in western Nevada were measured by neutron activation analysis techniques. Samples of both desert varnish and heart rock from a non-artifactual test boulder of andesite were studied and the elements tungsten, arsenic, antimony, thorium, uranium, manganese and cerium exhibited the greatest enrichments in the surface samples and may be of use for dating purposes.     

DETERMINING POTTERY PROVENANCE: APPLICATION OF A NEW HIGH-PRECISION X-RAY FLUORESCENCE METHOD AND COMPARISON WITH INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS*

A recently developed high-precision X-ray fluorescence (XRF) method, applied for the first time to the study of archaeological pottery, determines the abundances of 13 trace and four major elements from one X-ray spectrum acquired over a 1000 second counting interval. For replicate archaeological samples, the short-term and long-term measurement precisions were close to 1% for the ten elements measured with highest precision. These are comparable to the best results achieved on replicates of clay and pottery standards, and obsidian, using instrumental neutron activation analysis (INAA). High-precision XRF analysis, however, does not require a nuclear facility, and is markedly preferable to INAA in terms of the ease of both sample preparation and analytical procedure. Consequently, element abundance data can usually be provided by a single analyst within a few hours after the start of sample preparation. The accuracy of the method, determined by comparison with data of other workers on eight standard reference materials, averaged 2.4% for the ten best-agreeing elements. The effectiveness of the method for determining pottery provenance is demonstrated for a difficult problem, in which high-precision XRF analysis successfully distinguished the products of two nearby pottery manufacturers in Roman Galilee (Shikhin and Nahif) that had not been clearly differentiated by INAA. The greater effectiveness of high-precision XRF than INAA in this provenance study is a result of the different array of elements measured, and the higher precision obtained for certain elements, by XRF. These results suggest that high precision XRF has potential broad applicability for pottery provenance studies.     

NEUTRON ACTIVATION ANALYSIS OF ANCIENT BURMESE SILVER COINS WITH A LOW FLUX AMERICIUM/BERYLLIUM NEUTRON SOURCE

Nondestructive neutron activation analysis is by now a well-established technique for the analysis of ancient silver coins. The high activation cross-section of silver for thermal neutrons makes it possible to also use this method with the low neutron fluxes available from an isotopic neutron source. In this case due consideration must be given to minimize the self-shielding effect which is encountered with coins above a few tenths of a millimetre thickness. A simple method for the determination of the silver, copper and gold content in silver coins based on the self-shielding properties of silver alloys of different fineness is described. The method has been found to be useful for the quick routine assay of silver coins for the purpose of their classification. Seventeen ancient Burmese silver coins from three different cultural periods of Burma, and two British coins for comparison have been analyzed by this method.     

NEUTRON ACTIVATION ANALYSIS OF ARCHAEOLOGICAL MATERIALS: AN OVERVIEW OF THE ITN NAA LABORATORY,PORTUGAL

Instrumental neutron activation analysis (INAA) has been applied to archaeological samples at the Portuguese Research Reactor (RPI) since 1973, and the number of samples analysed has increased steadily since the mid‐1990s. Archaeometric applications of INAA at RPI include the analysis of archaeological ceramics and the stones used in monumental architecture (menhirs) and other historical monuments. A programme of analysis also exists for measuring the precision of and contributing to the certified values of geochemical reference samples. In addition, the study of interference factors is performed to obtain better accuracy in the determination of concentrations of some elements (e.g., corrections for spectral interferences from uranium fission products in the determination of barium, rare earth elements and zirconium).     

NEUTRON ACTIVATION ANALYSIS OF FAIENCE BEADS

A selection of faience beads has been examined using neutron activation analysis, with a view to distinguishing the provenance of individual specimens. Evidence is presented that the tin content in beads from British sites is significantly higher than in those from other areas. Characteristic features of beads from other sources are also discussed.     

COMPARISON OF NEUTRON ACTIVATION ANALYSIS FROM THE LAWRENCE BERKELEY LABORATORY AND THE HEBREW UNIVERSITY

Neutron activation measurements for Eu, Sc, Cs. Th, Ta, and Fe on 6 samples of pottery and rock by the Hebrew University and the Lawrence Berkeley Laboratory have been compared. The average disagreement exclusive of counting errors was 1.1%. The practical importance of this study to archaeology is that data taken on source materials in one laboratory can be used by the other. Methods of determining the consistency of measurements within a laboratory and sources oferrors are also discussed.     

GEOMETRICAL FACTORS IN THE NEUTRON ACTIVATION ANALYSIS OF ARCHAEOLOGICAL SPECIMENS

In the neutron activation analysis of museum specimens, for which sampling is not permitted, corrections must be applied to measured activities to take into account the sample shape and its position relative to the detector. Correction factors are derived for samples of cylindrical shape such as segmented faience beads and a model technique is suggested for those of irregular shape such as flint and obsidian implements. These techniques used in gamma-ray spectrometry with lithium-drifted germanium detectors enable elemental concentrations to be determined from the measured count rates.     

INSTRUMENTAL NEUTRON ACTIVATION BASED PROVENANCE STUDIES AT THE HEBREW UNIVERSITY OF JERUSALEM,WITH A CASE STUDY ON MYCENAEAN POTTERY FROM CYPRUS

A neutron activation programme aimed at archaeological provenance research operated at The Hebrew University of Jerusalem between the years 1974 and 1997. The history and accomplishments of that laboratory are presented. Endeavours to preserve unpublished results are described. Results on Cypriote pottery are presented.     

NEUTRON ACTIVATION ANALYSIS OF CERAMICS: PROBLEMS WITH TITANIUM AND CALCIUM

Titanium and calcium in ceramic materials can be analysed by neutron activation using a number of radioisotopes. Historical usage of scandium-47 for the analysis of both elements is reviewed. Measurements were made of the production and decay of ⁴⁷Sc sources prepared by SLOWPOKE reactor irradiations of pure titanium and calcium salts. Relative interferences were established and their effects calculated for a range of ceramic types. This study indicates that published values of the concentrations of titanium and calcium, using ⁴⁷Sc, must be seriously reassessed.