“…As a result, the stability of REE chloride complexes at elevated temperature has been subjected to much greater scrutiny than REE complexes involving other ligands. The hydrothermal speciation of the REE in chloride-bearing solutions has been investigated using a variety of experimental methods, including solubility (Gammons et al, 1996(Gammons et al, , 2002Migdisov et al, 2009), in situ UV-Vis spectroscopy Williams-Jones, 2002, 2006;Stepanchikova and Kolonin, 2005;, and in situ EXAFS studies (Mayanovic et al, 2002a(Mayanovic et al, , 2002b(Mayanovic et al, , 2007(Mayanovic et al, , 2009a(Mayanovic et al, , 2009b. The studies of Gammons et al (2002) and Migdisov et al (2009) involved simultaneous determination of the stability of a large number of REE in chloride-bearing solutions, whereas the other studies were devoted to single elements.…”