This work presents the development of a rapid technique for measuring the concentration of calcite in oxidized copper ore. The instrument is based on fluorescence spectroscopy in the visible and infrared range and is excited with a UV-LW lamp. The measurement takes substantially shorter times than standard procedures. Calibration models were adjusted via the correlation coefficient for validation (R-v(2)) and the error of prediction (RMSEP). Correlations higher than 0.92 were achieved for R-2. These results show the potential of the technique for portable or on-line estimation of calcite concentration in mining processes. Its performance under different granulometries is also addressed, showing the best performance for particle size between 0.01 and 0.04 mm. (c) 2005 Elsevier Ltd. All rights reserved.