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Standard techniques for geochemical and mineralogical characterisation are time‐consuming, they can involve significant sample preparation and they are prone to error. The aim of this work is to show how the emerging fast laser‐induced breakdown spectroscopy (LIBS) technique can be valuable for mineral exploration. For this purpose, the well‐established micro‐X‐ray fluorescence (µ‐XRF) technique was used to validate the LIBS data. Two ore samples from the platinum‐group elements (PGE) Lac des Îles mine (Ontario, Canada) were analysed both by LIBS and µ‐XRF. The fast mineralogical and elemental mapping provided by LIBS allowed the identification of four major silicate phases (chlorite, bytownite, actinolite, hornblende) and four minor sulfide phases (Pd‐bearing pentlandite, chalcopyrite, pyrrhotite, pyrite). Multi‐element chemical mapping and mineral characterisation using µ‐XRF corroborated the LIBS analyses for the composition, distribution and abundance of minerals in PGE ore samples. These findings demonstrate the ability of the LIBS technique to perform direct fast high‐resolution mapping of the chemical and mineralogical composition of PGE ore samples. This work highlights the advantages of LIBS for this application of being much faster and more sensitive to trace elements (e.g., Pd), as well as to low atomic number elements. [ABSTRACT FROM AUTHOR]

The laser-induced breakdown spectroscopy assisted by laser-induced fluorescence (LIBS-LIF) in a two-step process was used to measure the concentration of platinum (Pt) and palladium (Pd) by surface analysis of a solid ore core from the Lac des Iles mine followed by analysis of the same core that was pulverized and compacted. This work focuses mainly on the measurement of Pt since the case of Pd has been extensively discussed in previous work. The excitation of Pt is performed at 235.71 nm with fluorescence emission observed near 269.84 nm. Calibration was performed with synthetic samples prepared from the same ore as the samples studied and the calibration curve shows good linearity in Pt content over several orders of magnitude. A limit of detection (LOD) of approximately 0.15 parts per million (ppm) over an average of 200 laser shots was demonstrated. In contrast, conventional LIBS provides a LOD of about 21 ppm over an average of 200 laser shots due to low signal-to-noise ratio and spectral interference from other elements and does not meet the requirements for estimating the average Pt concentration in the ore. The Pt concentrations obtained using LIBS-LIF on solid ore are generally in good agreement with those obtained in its pulverized and compacted form, as well as with laboratory measurements made by conventional chemical methods. However, the comparison of the results obtained for Pd using LIBS-LIF with the laboratory showed a less satisfactory agreement, probably due to its more inhomogeneous distribution in the ore. Graphical abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • LIBS is successfully used to perform automatic mineral imaging and quantification. • QMA_EDS-SEM is used to guide the LIBS training and to validate the final results. • MCR-ALS allows element-to-mineral conversion of mixed-mineral-phase LIBS data. • Method can use laser spot size large enough to be suitable for field applications. • The point counting absolute errors are <3.5% for major minerals and <1% for minor minerals. Abstract Quantitative mineral analysis (QMA) performed using energy-dispersive x-ray spectrometry and scanning electron microscopes (EDS-SEM) provide reliable information on the mineral abundance and texture of prepared rocks. This information helps in the optimization of the mining and milling processes, and to define the value of a deposit. Real-time analysis of coarse rock streams would greatly enhance the decision-making processes driving the mining operation efficiency; however electron-microscope-based instruments are not yet adaptable for in-field measurements. Laser-induced breakdown spectroscopy (LIBS) has been used for elemental analysis in many environments but has not been employed for true mineral quantification and identification. This work presents a new method for mineral identification and quantification using LIBS, which could be scalable to perform automated mineralogy measurement in coarse rock streams. A set of rock tiles from mining operations in Australia had QMA performed using an EDS-SEM instrument and the resulting data were used to guide and validate the results obtained by LIBS. The use of a multivariate curve resolution – alternating least square (MCR-ALS) method applied to the LIBS data allowed the identification, quantification and imaging of minerals on rock tiles, even in the presence of mixed mineral phases within the laser spot area. Mineral abundance and imaging are obtained with success for the mineral phases selected in the present work, which includes bornite, chalcopyrite, pyrite, molybdenite, quartz, chlorite, K-feldspar, albite, fluorite and calcite. The method presented a mineral quantification root mean square error below 10% for the main minerals. In addition, mineral quantification by point-counting using single laser shots per LIBS measurement is demonstrated, achieving absolute errors below 3.5% for major minerals and below 1% for minor minerals. [ABSTRACT FROM AUTHOR]

Concrete structures experience severe damage during service, for example due to pitting corrosion of rebars caused by the ingress of chlorine (Cl) into the porous concrete structure. The ingress can be monitored using laser-induced breakdown spectroscopy (LIBS), a recently introduced civil engineering technique used to detect Cl in concrete structures in addition to conventional wet chemistry methods. The key advantages of LIBS are high spatial resolution, which is important when analyzing heterogeneous concrete samples, as well as the almost complete absence of sample preparation. To assess LIBS as a reliable analytical method, its accuracy and robustness must be carefully tested. This paper presents the results of an interlaboratory comparison on the analysis of Cl in cement paste samples conducted by 12 laboratories in 10 countries. Two sets of samples were prepared with Cl content ranging from 0.06 to 1.95 wt% in the training set and 0.23–1.51 wt% in the test set, with additional variations in the type of cement and Cl source (salt type). The overall result shows that LIBS is suitable for the quantification of the studied samples: the average relative error was generally below 15%. The results demonstrate the true status quo of the LIBS method for this type of analysis, given that the laboratories were not instructed on how to perform the analysis or how to process the data. [Display omitted] • First interlaboratory comparison of the quantitative determination of chlorine in cement pastes by LIBS. • 12 training samples and 8 unknown samples with a concentration range of 0.06–1.95 wt% Cl. • No restrictions regarding the equipment used and the data processing procedure. [ABSTRACT FROM AUTHOR]