MAGNETIC SUSCEPTIBILITY THICKNESS CORRECTIONS FOR SMALL ARTEFACTS AND COMMENTS ON THE EFFECTS OF‘BACKGROUND’MATERIALS*

Correction factors for magnetic susceptibility measurements on thin (<c. 50 mm thick > artefacts have been determined experimentally for a KT‐5 Exploranium G S. instrument using prepared blocks of Whin Sill dolerite. The cor rection factor is large (> 1.4) for samples less than 10mm thick, and reduces to 1 01 for samples of 50mm thickness. Measurements on thin samples can also be affected by the backing or substrate material on which they are measured. ‘Background’material, for example, soil or plaster, can contribute significantly to recorded measurements on artefacts, particularly for thin artefacts with low susceptibilities     

MINERALOGY OF BOHEMIAN GREEN EARTH PIGMENT AND ITS MICROANALYTICAL EVIDENCE IN HISTORICAL PAINTINGS

While the most famous historical green earth deposits in Italy and Cyprus were exceptionally rich in celadonite, the deposits near Kadaň, Czech Republic, consisted of thin Fe‐rich celadonite impregnations accompanied by interstratified celadonite/smectite. In superimposed tuffs, smectites become prevalent and their colour changes from forest to olive green. Powder X‐ray microdiffraction and infrared microspectroscopy permit us to distinguish between green earth minerals in microsamples taken from works of art. The Ti contents and the Fe/Mg ratios help to indicate the presence of Bohemian green earth from Kadaň. We found this material in local 18th‐century works of art and also in paintings by Anton Kern (1709–47).     

LITHIC RESOURCES IN THE EARLY PREHISTORY OF THE ALPS*

Rocks, which are ubiquitous in archaeological sites as chipped or polished tools, were important factors in the prehistoric Alpine economic system. Archaeometric characterization and identification of source areas open the path to a more detailed understanding of the production and diffusion mechanisms behind Alpine lithic industries. An overview of the situation from the eastern to the western Alps in the Mesolithic, the Neolithic and the Copper Age illustrates current debates and issues.     

THE FIRST ARCHAEOMETRIC CHARACTERIZATION OF ROMAN MILLSTONES FOUND IN THE AQUILEIA ARCHAEOLOGICAL SITE (UDINE,ITALY)*

An archaeometric study of all the Roman millstones preserved today in the National Archaeological Museum of Aquileia, the ancient capital of the X Regio Augustea –‘Venetia et Histria’ located on the Friuli plain (northeastern Italy), has been recently envisaged to define their geological–geographical provenance. We present here the results of the first step of the research, which is aimed at characterizing all of the definitely allochthonous lithologies. In order to carry out petrography on thin‐section and geochemical analyses, 10 small samples were picked out directly from Pompeian‐style millstones (catilli and/or metae) and rotary querns. Five different lithologies originating in various Italian regions were recognized: eight samples consist of pale‐ and dark‐grey lavas from the Venetian Volcanic Province, Vulsini Volcanic District (Latium), Etna Volcano and Pantelleria island (Sicily), whereas two samples were shown to be made of green garnet‐bearing schists (pietra ollare) from the Western Italian Alps. The presence of Alpine pietra ollare in northeastern Italy, used to produce pots and food containers, was established for numerous classical findings at Roman and Middle Age sites, but the analysed items represent the first evidence for the utilization of this kind of stone to produce mills during the Roman epoch.     

COLD NEUTRON PROMPT GAMMA ACTIVATION ANALYSIS—A NON‐DESTRUCTIVE METHOD FOR CHARACTERIZATION OF HIGH SILICA CONTENT CHIPPED STONE TOOLS AND RAW MATERIALS*

Recently, several archaeometrical projects have been started on the prehistoric collection of the Hungarian National Museum. Among the analytical methods applied, non‐destructive prompt gamma activation analysis has a special importance. We have also tested the potential of this method on chipped stone tools, with the aim of determining their exact provenance. On the basis of major and trace element components, characterizations of stone tools and their raw materials—silicites (flint, chert, radiolarite and hornstone) as well as volcanites (felsitic porphyry and obsidian)—were performed. We discuss some important results concerning each group, as case studies. Compiling the data set of different PGAA analysis series, compositions of 110 samples are reported, including 76 archaeological pieces. In the future, we plan to extend the number of investigated objects in each class.     

OCCURRENCES OF GREEN EARTH PIGMENT ON NORTHWEST COAST FIRST NATIONS PAINTED OBJECTS*

An analytical study of First Nations painted objects from the Northwest Coast showed that green earth (celadonite) was used as a green pigment by Tlingit, Haida and Tsimshian artists. Green earth appears to have been used less frequently by Heiltsuk and Kwakwa ka ’wakw artists and was not found on Coast Salish or Nuu‐chah‐nulth objects. Microscopical samples of green paint from 82 Northwest Coast objects, as well as several pigment sources and mineral specimens, were analysed using Fourier transform infrared spectroscopy or X‐ray diffraction. Green earth was the most frequently identified green pigment, found in approximately 40% of the samples.     

THE SECTILIA PANELS OF FARAGOLA (ASCOLI SATRIANO,SOUTHERN ITALY): A MULTI‐ANALYTICAL STUDY OF THE GREEN,MARBLED (GREEN AND YELLOW), BLUE AND BLACKISH GLASS SLABS

Analyses at the Cu–K, Fe–K and Mn–K edge were performed to study the green, marbled (green and yellow), blue and blackish (deep greyish olive green) glass slabs decorating three sectilia panels from the archaeological site of Faragola. Results indicate that all slabs were made by mixing siliceous sand with natron, sometimes probably mixed with small percentages of plant ash. Cu²⁺ and Pb antimonates should be responsible for the opaque green colours. The dark green and yellow portions of the marbled slabs are respectively comparable to the slabs comprising only one of these colours. Cu²⁺ together with Ca antimonates probably produced light blue slabs, whereas cobalt was used to produce dark blue slabs. We consider it possible that the abundance ratio of Fe²⁺/Fe³⁺ and the complex Fe³⁺S^2? would have an effect on the blackish slabs. The contribution of Mn cannot be ascertained even if it could have played a role in darkening glass colour. The comparison between the chemical composition of Faragola samples and several glass reference groups provided no conclusive evidence of provenance; whereas, the presence of a secondary local workshop can be hypothesized.     

THE EGYPTIAN GREEN PIGMENT: ITS MANUFACTURING PROCESS AND LINKS TO EGYPTIAN BLUE*

The chemical and structural analysis of raw Egyptian blue and green pigment cakes and of 50 pigment samples taken from paintings kept in the Louvre Museum was performed using a set of analytical techniques (X‐ray powder diffraction, transmission and scanning electron microscopy, Raman microscopy and UV spectrophotometry). The structural and morphological study of modern samples prepared on the basis of these results has provided technological data that help to explain ancient procedures. The role of the firing temperature, the atmospheric conditions in the furnace and the cooling rate are considered. The difference between Egyptian blue and Egyptian green pigment is proved. Manufacturing processes for their deliberate synthesis are proposed.