E. H. T. WHITTEN; Molar-ratio and Harker diagrams in portraying the actual chemical variability of granitoid suites. Journal of the Geological Society ; 153 (1): 121–125. doi: https://doi.org/10.1144/gsjgs.153.1.0121
Recent publications show that molar-ratio diagrams preserve absolute compositional variations of certain mafic igneous rock assemblages, while traditional Harker diagrams for all igneous rocks obfuscate relationships. For some Australian granitoid suites, molar-ratio diagrams illustrate chemical variations accurately and permit quantitative objective testing of petrogenetic models (e.g., restite model) with observed chemical compositional data.