Laser-Induced Breakdown Spectroscopy for Rapid Elemental Analysis of Drillcore

The elemental and mineralogical contents of rock drillcore can be analyzed using a variety of methods. For efficient exploration the characterization of the drillcore should be performed rapidly, so that the further drillings can be better planned and unnecessary costs can be reduced. In this paper, laser-induced breakdown spectroscopy (LIBS) is studied as a potential rapid on-line method for automated elemental analysis of drillcore. The method is based on a pulsed laser beam that transforms a small volume of the sample into plasma. Individual elements in the plasma have characteristic emission patterns detectable by a spectrometer. Based on the measured spectra the amount of different elements in the sample can be estimated. Drillcore samples from a gold mine in Finland are used as test cases in this study. The LIBS measurements are compared to laboratory analysis results as well as to hyperspectral imaging results obtained in the short-wave infrared region. It is shown that the LIBS method can produce similar elemental concentrations as the laboratory measurements. Moreover, based on the elemental contents, some minerals can be identified and the LIBS information can be used to confirm and complete the results of the hyperspectral analysis. However, the spot size of the LIBS measurement is very small, meaning that a large number of measurements must be taken to reach a representative sampling result for large drillcore volumes. On the other hand, high spatial resolution is easily achieved.