Abstract

Reflectance spectrometers with automated scanning capabilities can gather compositional information directly from the surface of drill core. To showcase the usefulness of this analytical technique, 300 m of drill core from the Olympic Dam iron oxide copper-gold (IOCG) deposit, South Australia, were scanned using HyLogger. The reflectance spectra (400–2,500 nm) were analyzed to identify hematite and phengite, which are the most important alteration minerals at Olympic Dam. The results were plotted as a function of depth to produce a log that accurately identified ore-bearing and barren rocks. The position of the most intense absorption feature between 850 and 970 nm was found to correspond to iron concentration, and the intensity of the most intense absorption feature between 2,190 and 2,230 nm was found to correspond to aluminum concentration. In addition, phengite located near the ore-bearing zone was found to contain more aluminum than phengite located in the barren rocks, and this difference in phengite mineral chemistry was observable in the reflectance spectra between 2,190 and 2,230 nm.

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