EPR spectroscopy can help with paint pigment provenance

Full text: The microwave magnetic spectroscopic technique EPR can be used to determine the presence of paramagnetic impurities in paint pigments, and the purity of composition regarding the main colourant. Hence EPR can help determine provenance of pigments, just as it can for gemstones. Specimens of Lapis Lazuli (synthetic, Afghanistan, Chile, Greenland) showed quite recognisably different spectra, at room temperature, in a Varian E-12 X-band spectrometer (9.1 GHz frequency). Similarly, specimens of yellow ochre, two imported into Australia, one North Australian, another 95% pure Goethite, showed recognisably different spectra. The North Australian one uniquely gave a known radiation damage signal from quartz, perhaps to be expected, given the abundance of radioactive ores in the region. Further samples have been obtained and the results from these will be reported