31st International Symposium on Archaeometry Budapest, 27 April 1 May 1998

Production and Characterization of Egyptian Blue and Green Frit

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4. Production and Characterization of Egyptian Blue and Green Frit

M.F. Ali*, P.L. Bianchetti**, F. Talarico**, M.G. Vigliano**

*Cairo University-Faculty of Archaeology - Dept. of Conservation

**Instituto Centrale per il Restauro, Roma

The study of Egyptian blue and green frit were developed owing to the knowledge of the pigment production techniques. Most of the published works to treat the characterization and the production of Egyptian blue, while a few works deal with the green frit. The aim of the present work was to produce and to characterize green frit from pure chemical components or from Egyptian materials (desert sand, copper objects).

Grounded materials were added of sodium carbonate as flux then mixed with water or Arabic gum to get cakes and heated in a muffle furnace to various temperatures, obtained products were analyzed by XRD, colourimetric analysis and examined under mineralogical microscope. Cuprorivaite and tridymite characterize all the samples of pigments obtained at 850 oC and the appearance blue colour, samples heated to 1050 oC denote the disappearance of cuprorivaite and the appearance of a green glass (green frit). It seems that wollastonite is generally present in mixtures containing a lower amount of copper.

We observe the presence of green glass and tenorite, while cuprorivaite is absent in the samples if pigment obtained under reducing atmosphere. Results should indicate that 950 oC is a transition temperature where it is possible to observe different processes, probably due also to kinetic effects.

5. Pilot Validation Study for the use of Bromine as a tracer of Sea and Salt routes in ancient cultures

E. Aloupi*, A. Karydas**, T. Paradellis**, I. Siotis***

*THETIS - Science and Techniques for Art History Conservation Ltd., 41M. Moussourou str., 116 36 Athens

**Laboratory for Material Analysis, Inst. of Nuclear Physics, NCSR "Demokritos", 15310 Ag. Paraskevi, Greece

***Inst. of Nuclear Physics, NCSR "Demokritos", 153 10 Ag. Paraskevi, Greece

The aim of the project is to validate a new approach for the tracing of sea-salt routes in ancient material culture. Salt, on account of its importance for the human organism, has played and continues to play a significant role in the history of peoples and has on occasions been the pretext for war. In the archaeological record the production and circulation of salt can be traced from as early as the Neolithic period in Egypt and Europe. In spite of its importance, due to the fact that alkali salts are easily dissolved and are difficult to trace in ancient material culture, there is a complete lack of scientific evidence concerning salt contacts. The key-idea is the use of bromine and its compounds as a tracer of the contact between sea-water and sea-salt with ceramic and lithic artefacts or structures. Bromine offers a very powerful discriminating criterion between marine and terrestrial environments. Br occurs in the hydrosphere as soluble bromide salts. Its concentration in sea-water is 65-70 ppm while in earth's crust and streams is only 4.0 and 0.02 ppm, respectively. This is further accentuated between the marine and terrestrial biosphere (seaweed, sponges, shells, plants etc.) due to the formation of organic bromine compounds. In the case of salt and salt brines (the main source of Br in modern industrial practice) it exceeds 2500 ppm.

Experimentally, Br concentration can be measured by using the straightforward and well established X-Ray Fluorescence (XRF) technique, which through the recent development of high resolution, ambient temperature, portable instruments lends itself for quick, non-destructive, in situ measurements and surveys with sensitivity of a few ppm.

In order to validate the technique before it can be reliably applied to address archaeological questions, a series of preliminary tests and measurements were performed on ceramics and lithic artefacts subjected to contact with sea water and salt under laboratory conditions. In addition, several ceramic artefacts which are known through the archaeological record to have served as salt or salt brine containers recovered in inland burial environments were also analysed. To this effect the Br concentration was measured on fragments of shallow dishes used in the "briquetage" salt making technique, as well as on "oxygaron" vases (containing vinegar and garum, a fish sauce) found in Eleftherna, an inland archaeological site in Crete. The measurements will be compared with Br concentrations in similar artefacts for which the archaeological record excludes salt contact. The results are very encouraging and confirmed the view that the Br concentration measured as a function of depth from the surface provides a unique "sea salt" signature.

6. EDXRF study of Tupiguarani archaeological ceramics from the north of Paraná state in Brazil

Appoloni, C. R. *, Espinoza-Quinones, F. R.*, Aragao, P.H. *, Cuevas, A. M. **,***, Cesareo, R. ***, Coimbra, M. M. *, Borlino, C.C.***, do Nascimento Filho, V. F.****

*Physics Department, State University of Londrina (UEL), Londrina, PR, BRAZIL

**National Center for Scientific Research of Havana, CUBA

***Institute of Mathematics and Physics, University of Sassari, ITALY

****Physics and Meteorology Department, ESALQ, University of Sao Paulo, Piracicaba, SP, BRAZIL

The first evidences of human settlement in Paraná state are from 10000 years ago. In this region, about 1500 years ago, horticulturalists and ceramists populations appeared, represented by the Tupiguarani and Itararé groups. The Tupiguarani lived in the valley regions of the Paraná, Ivaí, Tibagi and Iguaçu rivers. The Tupiguarani sites are related to the Guarani indians ancestors. Tupiguarani populations lived in the region of the Santa Dalmacia farm at the end of the 16th century or at the beginning of the 17th century and they had contact with the colonizers, probably Spanish, due to the observed changes in the pottery production characteristics. The Santa Dalmacia farm archaeological site was accidentally discovered in 1990 and belongs to Cambé city municipality, north of Paraná state, south of Brazil.

The objectives of this work are: to analyse the ceramic paste composition, as well as the superficial layer of the ceramic fragments, in order to get information about the pigment composition of the plastic decoration; comparison of the ceramic pastes composition between typical Tupiguarani fragments and the fragments that present characteristics of contact with the European colonizers.

The analytical technique employed was the energy dispersive X-ray fluorescence (EDXRF), in two different experimental set-ups. The first set of measurements was carried at Sassari University with two X-ray tubes (30 kV and 0.1 mA; 80 kV and 5 mA), secondary targets of silver and gadolinium, and an Amptek Si-PIN detector, thermoelectrically cooled, having an 70 mm Be entrance window and 300 mm thickness. The second one was carried at Sao Paulo University using a 238Pu radioactive source and a Si(Li) detector with a Be window. X-ray spectra were processed and quantified (at Sassari and Londrina) by using the AXIL program.

The ceramic pastes can be characterized by a low Ca content, and a systematic presence of relatively high concentrations of Ti. Fe is also always present at high levels, and Ni, Cu and in some cases Zn at level of traces; Rb, Sr, Y and Zr are also present, and Ba in all samples at low concentration.

The black pigment in the pottery plastic decoration is due to the presence of Mn, the red pigment is due to the presence of Fe, while the white pigment is characterized by the presence of Ba.

Other qualitative and quantitative results were obtained for each kind of ceramic fragment group and will be also presented.

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