A prototype instrument using magnetic resonance has been constructed for quantitative measurement of selected copper minerals, in bulk samples obtained from a number of commercial ore deposits. The instrument has been developed to provide rapid on-line determination of phase concentration. The on-line measurement of copper mineral phase would be of considerable assistance to the mineralogist or process engineer for process optimisation. Ultimately, the underlying method may be applied in ore streams on conveyors or batch samples. This paper describes the development of the instrument and measurement methods, with particular emphasis on chalcopyrite, focusing on the design route for instrument deployment. Quantitative results regarding detection limits and accuracy for dilute ore concentrations are presented. In addition, effects due to crushing and grinding are discussed. Owing to the very high selectivity of the technique, it has been possible to demonstrate mineral phase resolution of 0.1 wt% in bulk samples. Crown Copyright (c) 2007 Published by Elsevier Ltd. All rights reserved.