On Pyroxene Molecules in the CIPW Norm

Abstract

AbstractBarth argued that the CIPW conventions governing the calculation of normative pyroxenes and olivines are based upon inadequate or incorrect mineralogical information and should be abandoned. The real occasion for the conventions appears to be petrological, not mineralogical. Qualitative agreement between norms and modes of undersaturated rocks requires the use of these or very similar conventions. Ease of calculation is no longer a major consideration and a more realistic set of rules could now be adopted if it were available.