First analytical results on the Roman glass of the archaeological site of Luni , Italy Monica Ganio 1,3 , Kris Latruwe 2 , Frank Vanhaecke 2 , Patrick Degryse 3 , Marc Walton 1 , Laure Dussubieux 4 1 NU-ACCESS Northwestern University/Art Institute of Chicago CEnter for Scientific Studies in the Arts, 2145 Sheridan Rd, Evanston, IL 60208, USA 2 Department of Analytical Chemistry, Ghent University, Krijgslaan 281 – S12, BE-9000 Ghent, Belgium 3 Department of Earth and Environmental Sciences, Section Geology, Katholieke Universiteit Leuven, Celestijnenlaan 200E, BE-3001 Leuven, Belgium 4 Elemental Analysis Facility, The Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, IL 60605, USA Introduction The Roman colony of Luni (Liguria, NW Italy) was founded in 177 AD. Its fortune is related to the intensive exploitation of the marble quarries on the Apuan Alps. At the maximum at its splendor under the Julio-Claudian dynasty, the Civitas Imperialis of Luni was put to an end by a violent earthquake at the end of the 4 th century AD 1 . This study focuses on 31 glass fragments (1 st to 4 th century AD) mainly colorless (cls) or naturally colored. Elemental composition analysis and Sr-Nd isotopic analysis are used to trace the primary origin of the raw materials used in glass making. Methodology Elemental analysis have been carried out at the Field Museum of Natural History, Chicago, using a New Wave UP213 laser ablation system coupled with Varian ICP-MS 2 . Sr and Nd isotopic analysis were performed at the University of Ghent using a Thermo Scientific Neptune multi-collector ICP-MS after sequential extraction on columns 3,4 . Sample preparation was performed in a class 10 clean lab. XRF analysis have been carried out using a ELIO X-Ray Fluorescence Spectrometer (XGLab), equipped with a Rh tube, and operated at 40kV and 100 µA for 300s, with a 1mm spot size. Data reduction was performed using ImageJ 5 to generate complied spectra for illustration of elemental trends and correlations. Results and discussion 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 Fe 2 O 3 (wt%) TiO 2 (wt%) cls-Mn cls-Sb cls-SbMn naturally colored purple blue amber yellow Fig.1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.00 0.20 0.40 0.60 0.80 1.00 MnO (wt%) Sb 2 O 3 (wt%) cls-Mn cls-Sb cls-SbMn naturally colored Fig.2 Ca K α Si K α Ca K β Fe K α Pb L α Sr Kα Sr Kβ Sb K α Mn Kα Ti K α Fe K β Pb Lβ K Kα S K α Cr K α Ti K β Cu K α Ni K α Fig.5 1. Durante (2001) Ministero per i Beni e le Attivita’ Cultuali, La Spezia; 2. Dussubieux et al. (2009) International Journal of Mass Spectrometry 284; 3. De Muynck et al. (2009) Journal of Analytical Atomic Spectrometry 24; 4. Ganio et al. (2012) Journal of Analytical Atomic Spectroscopy 27; 5. Rasband WS, Image J., http://imagej.nih.gov/ij; 6. Mirti et al. (1993) Archaeometry 35; 7. Mirti et al. (2000) Archaeometry 42; 8. Mirti et al. (2001) Archaeometry 43; 9. Arletti et al. (2006) Applied Physics A 83; 10. Arletti et al. (2008) Archaeometry 50; 11. Gallo et al. (2013) Journal of Archaeological Science 40; 12. Ganio (2013) PhD thesis; 13. Jackson (2005) Archaeometry 47; 14. Paynter (2006) Journal of Archaeological Science 33; 15. Foster & Jackson (2009) Journal of Archaeological Science 36; 16. Foster& Jackson (2010) Journal of Archaeological Science 37; 17. Brems (2012) PhD thesis; 18. Jackson (1997) Annales AIHV; 19. Freestone et al. (2002) Archaeometry 44. Fig.4 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5 -3.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Nd Al 2 O 3 (wt%) cls-Mn cls-Sb cls-SbMn naturally colored purple blue amber yellow Apulia sand IT87 Syro-Palestinian sand and raw glass Basilicata sand IT85 Fig.3 The lower portion of fig.5 is a cropped area of the data-set image one pixel width and 4096 pixel (number of available channels) in length, produced using ImageJ. The trace shown above is the sum of all the spectra identifying the position of the X-ray fluorescence bands corresponding to the major elements. This sum spectrum shows a number of elements that are normally found in archaeological glass: Si, Ca, Ti, Mn, Fe, Pb, and Sb. High intensity peaks are orange/yellow, while the background is shown as a light blue. Colorless (fig.6) and naturally colored (fig.7) glasses show the potential of this qualitative examination method. Mn-decolored and Sb-decolored are clearly different (fig.6). The presence of Pb in the mixed-decolorant glasses suggests that recycling was taking place to some extent 18,19 . Naturally colored glasses show relatively high contents of Mn, possibly suggesting that the pale color is due to unsuccessful redox equilibrium between iron and manganese 6 . Conclusions The isotopic composition, with εNd>-6.0, excludes a Western Mediterranean provenance, suggesting either a Syro-Palestinian or southern Italian origin of the silica raw material. Alumina contents, together with trace elements, help in discriminating the possible sources, pointing to the of a Syro-Palestinian sand for the production of the Luni glasses. The use of qualitative XRF as a quick sample characterization method is shown to be a powerful tool, able to highlight the main differences in glass samples and discriminating compositional groups without the need for quantification. The results are in good agreement with the LA-ICP-MS data. 0.8 5.8 10.8 15.8 20.8 25.8 Energy (KeV) cls-Mn cls-SbMn cls-Sb Fig.6 0.8 5.8 10.8 15.8 20.8 25.8 Energy (KeV) cls-Mn cls-SbMn cls-Sb naturally coloured Fig.7 LA-ICP-MS results indicate that all samples are soda-silica-lime glass. Blue glasses (fig.1) show higher Fe 2 O 3 content for comparable titanium levels, a composition not unusual in Roman blue glasses 6-12 . Mn and Sb are the main decolorants (fig.2). Sb-decolored glasses contain lower levels of lime and alumina than the Mn- decolored ones, in agreement with literature data 12-16 . A Western Mediterranean origin for the silica raw materials is excluded by the relatively positive εNd values 16 . Alumina contents (fig.3) suggest the use of a Syro-Palestinian silica raw material for the production of Luni glasses 12,17 . contact: monica.ganio@northwestern.edu