A prototype mineral analyser using magnetic resonance has been configured with two sensors for measurement of the copper sulphide mineral chalcopyrite (CuFeS(2)) in ores and slurries. In the first configuration, a sensor was optimised to quantify chalcopyrite content in rock fragments. The detection limit for these measurements was estimated at 15 mg of contained chalcopyrite in rock fragments of mass range of 1.4-3.7 g. The magnetic resonance results correlated with separate quantitative X-ray diffraction measurements of chalcopyrite content. The second configuration was used to quantify chalcopyrite content in mineral slurries. Tests on prepared slurry samples with known chalcopyrite concentration were performed, yielding a standard error of 0.1 wt% across the sample range of 0.5-4.0 wt%. Measurements on a commercial mineral slurry were also performed. The design of an online industrial analyser is discussed with reference to processing slurries with high solid loadings, containing phases such as chalcopyrite and other minerals. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.