EASYGRESGRANT—A Microsoft Excel spreadsheet to quantify volume changes and to perform mass-balance modeling in metasomatic systems

► Constant mass, constant volume or immobile elements are utilized as reference frames.
► A reliable selection of immobile elements is achieved for mass-balance modeling.
► Immobile element selection is carried out from clusters of slopes or volume factors.
► Graphical and statistical methods are used to verify the immobile element selection.
► Elements are plotted in Ca−C0 plots without scaling concentrations to avoid errors.