Localized quantification of anhydrous calcium carbonate polymorphs using micro-Raman spectroscopy

Micro-Raman spectroscopy is a powerful technique for qualitative and quantitative analysis of different mineral mixtures. In this paper, micro-Raman spectroscopy was used for quantification in local regions (180 x 180 mu m area) of ternary mixtures of the synthetic calcium carbonate (CaCO3) polymorphs (vaterite, aragonite, calcite) as well as CaCO3 formed during the carbonation of nanolime suspension. The obtained results of localized quantification were in agreement with the detected concentrations obtained from bulk quantitative phase analysis of X-ray powder diffraction patterns. The detection limits were found to be below 0.5 wt.% for each CaCO3 polymorphs. Through the use of 2D mapping, localized quantification of CaCO3 polymorphs can be achieved. This information could be potentially useful for conservation of valuable Cultural Heritage objects, as it might influence the consolidation treatment chosen. (C) 2017 Elsevier B.V. All rights reserved.