News
28.04.2022New paper published with contribution from the Raman Spectroscopy Laboratory
PhD. Tariq Jawhari, technical responsible of the Raman spectroscopy Laboratory at the CCiTUB, participated in the publication of the paper entitled "Colours of Gemmy Phosphates from the Gavà Neolithic Mines (Catalonia, Spain): Origin and Archaeological Significance".
In this study, has been analysed the distribution, depending on the color, of the variscites found and exploited in the Gavà mines as a decoration product during the Neolithic. The change of color in the variscites of the Gavà mines has been studied by various CCiTUB laboratories, including Diffraction of X-rays, the Scanning Electron Microscopy (SEM-EDS), the Electronic Microprobe and Raman Spectroscopy.
The abstract of the paper is the following:
"In the Neolithic Gavà mines, variscite and turquoise were exploited for ornaments manufacturing, although some prospective pits and tunnels were dug on other similar greenish minerals such as smectite or kandite. A 3D study of the distribution of mineral phases allows us to determine the parameters involved in variscite colours. Methods are comprised of quantitative colourimetry, thin section petrography, SEM-BSE-EDS, EMPA, XRD, Raman spectroscopy, and 57Fe Mössbauer spectrometry. Mapping of the mines indicates that colour is not directly dependent on depth. Although variscite from Gavà is poor in Cr3+ and V+3 compared with gemmy variscite from other localities, the deep green samples content has the highest values of Cr3+. In the case of cryptocrystalline mixtures with jarosite, phosphosiderite, or goethite, variscite tends to acquire a greenish brown to olivaceous hue. If white minerals such as quartz, kandite, crandallite, or alunite are involved in the mixtures, variscite and turquoise colours become paler."
The paper can be read at the follwing link:[+].