In the present paper the analytical methods for determination of elemental and isotopic content in glass mosaic (tesserae) are presented. The history of the glass and the tesserae is given. The chemical content of glasses is described as well as the list of determined elements and isotopic content in glass by different analytical methods is given. A short discussion about the possibility of different methods is presented. The difference between the glasses produced using plant ash and natural soda is given. Some examples of different glasses found in Bulgaria are compared with the glass found in other states. The possibility for determination of the place of glass production using isotopic determination is discussed. Some examples about the possibility to determine the isotope ratios of 87Sr/86Sr and 143Nd/144Nd, 208Pb/206Pb and 18O are given.