Hello. Often high temperature data are not available. I am missing the melting heat of many coumpounds. However, rather precise binary phase diagrams are available. (my examples deal with silicates, say CaO-SiO2 for example, http://www.npl.co.uk/mtdata/demo/dgox1.html) I would like to know if a phase diagram contains some useful information to evaluate this melting heat. Are there some thermodynamics fundamentals that may help? Are there other useful track, like empirical rules ... ?