An analytical study was carried out on more than 80 samples of green paint coming from 14 different Roman sites in Switzerland and from Pompeii. A geological reference material composed of celadonites from Cyprus, Italy and Brazil, glauconite from Switzerland and the Netherlands, chlorite from the Swiss Alps and illite from Central Massif, France, were analysed too. Analytical methods used are: XRD, SEM, IRS, XRF, EDS, EPMA, Mössbauer spectrometry and optical microscopy. The aims of the study are the characterization of the green pigments used, an eventual determination of their origins and knowledge of their preparation and application techniques. The pigments identified on the different sites are: celadonite, glauconite, chlorite (chamosite), malachite and verdigris.