Introduction Mosaic tesserae are primarily made out of stones, ceramics or glass. The tesserae being analyzed were made of glass. Glass samples can be analyzed via X- Ray Fluorescence (XRF), Raman Spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR). XRF spectrometry is a common instrument for analyzing glass samples because it allows for more efficient fieldwork, sufficient detection limits and is non- destructive. XRF instruments can detect from Ca to Pb in SiO 2 . The main coloring agents in the glass tesserae analyzed were found to be Fe, Cu, Mn, and Co. Energy-dispersive XRF spectrometry was used to analyze the tesserae samples. Instrumentation •Bruker Tracer III-V, yellow filter, 8 A, 40keV •Bruker Tracer III-SD •with vacuum pump, no filter, 25 A, 15 keV •With out vacuum pump, yellow filter, 11.7 A, 40keV References 1.Perdomo, M. A. F. M. S. T. F., Mosaics in Mexico. Artes de Mexico: Mexico City, 2006. 2.Fiori, C.; Rocuzzi-Fiorentini, I.; Vandini, M., Colors and stories of the Italian mosaics. Monogr. Mater. Soc. 2001, 5 (Art of Ceramics), 149-172. 3.Janssens, K. Modern Methods for Analysing Archaeological and Historical Glass. John Wiley & Sons Ltd: United Kingdom, 2013; Vol. 1, p 309. 4.James, L., Byzantine glass mosaic tesserae: some material considerations. Byzantine and Modern Greek Studies 2006, 30 (1), 29-47. 5.Silvestri, A.; Tonietto, S.; D’Acapito, F.; Molin, G., The role of copper on colour of palaeo-Christian glass mosaic tesserae: An XAS study. Journal of Cultural Heritage 2012, 13 (2), 137-144. 6.Douglas A. Skoog, F. J. H., Stanley R. Crouch, Instrumental Analysis. Brooks/Cole: Canada, 2007. Acknowledgements I would like to thank Dr. Mary Kate Donais for all of her guidance throughout this project. Results Conclusions •Through the XRF analyses and principal component analyses (PCA), some of the key elements within the mosaic tesserae were identified. •The PCA of all the Dark Blue tesserae showed that the samples varied only in relative elemental concentration. •The PCA and overlaying plot of the varying Dark Blue homogeneity study tesserae showed that the Dark blue tesserae are not homogeneous. Method The tesserae were separated by visual inspection and analyzed via XRF. Spectrometry. For some tesserae all six sides were analyzed under vacuum conditions. Also for each color one whole tesserae was analyzed and then the tesserae was crushed and the crushed tesserae was analyzed. All Tesserae Scores/Loadings Plots Fe Cu Sb Ca Mn Fe Cu Sb Ca Mn Dark Blue Homogeneity Scores/Loadings Plots Fe Cu Sb Pb Dark Blue Scores/Loadings Plots 0 0.2 0.4 0.6 0.8 1 1.2 0.019 0.994 1.969 2.944 3.919 4.894 5.869 6.844 7.819 8.794 9.769 10.744 11.719 12.694 13.669 14.644 15.619 16.594 17.569 18.544 19.519 20.494 21.469 22.444 23.419 24.394 25.369 26.344 27.319 28.294 29.269 30.244 31.219 32.194 33.169 34.144 35.119 36.094 37.069 38.044 39.019 Intensity X-Ray Energy (keV) Overlap of Dark Blue Tesserae Whole and then Crushed Dark Blue B crushed Dark Blue B whole Dark Blue Crushed Dark Blue F crushed Dark Blue F whole