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Comparison of 68 alluvial diamonds from three placer deposits in Brazil (Arenapolis, Mato Grosso, Boa Vista, Roraima, and Canastra, Minas Gerais) showed that they had similar crystal shapes, body colours and growth or resorption surface texture development. The concentrations and aggregation states of nitrogen impurities and their carbon isotope compositions were also similar. The diamonds from Boa Vista had a higher proportion with radiation spots compared with the other deposits. The majority of the diamonds from Arenapolis (70%) exhibited transport- related abrasion textures while those from Boa Vista and Canastra were characterised by the absence or a low occurrence (below 15%) of such textures, indicating that these diamonds are derived from nearby kimberlitic sources. The composition of the mineral inclusions was similar for diamonds from all three deposits. The diamonds formed in a strong to moderately depleted peridotitic mantle, with only minor involvement of eclogitic sources., Comparison of 68 alluvial diamonds from three placer deposits in Brazil (Arenapolis, Mato Grosso, Boa Vista, Roraima, and Canastra, Minas Gerais) showed that they had similar crystal shapes, body colours and growth or resorption surface texture development. The concentrations and aggregation states of nitrogen impurities and their carbon isotope compositions were also similar. The diamonds from Boa Vista had a higher proportion with radiation spots compared with the other deposits. The majority of the diamonds from Arenapolis (70%) exhibited transport- related abrasion textures while those from Boa Vista and Canastra were characterised by the absence or a low occurrence (below 15%) of such textures, indicating that these diamonds are derived from nearby kimberlitic sources. The composition of the mineral inclusions was similar for diamonds from all three deposits. The diamonds formed in a strong to moderately depleted peridotitic mantle, with only minor involvement of eclogitic sources.

Short-wave infrared (SWIR, 1.90-2.36 micron) and long-wave infrared (LWIR, 8.1-11.1 micron) hyperspectral images collected using the SisuROCK system were used to develop an automated methodology for generating kimberlite dilution maps. Smoothed and denoised images from two Snap Lake (Northwest Territories, Canada) kimberlite drill cores were processed, and SWIR and LWIR spectral endmembers were extracted from the images with each mineralogical endmember assigned to one of four compositional groups: undiluted kimberlite, microdiluted kimberlite, micro- and macrodiluted kimberlite, and crustal rocks. These endmembers were used to classify the SWIR and LWIR images, and the results were validated using linescan data, drill core logs, petrology reports, and the results of X-ray diffraction, Raman spectroscopy, and Micro-Fourier Transform Infrared (FTIR) spectroscopy. This study demonstrates that hyperspectral imagery can be used to generate dilution maps for hypabyssal kimberlites that far supersede other current techniques in terms of spatial resolution., Short-wave infrared (SWIR, 1.90-2.36 micron) and long-wave infrared (LWIR, 8.1-11.1 micron) hyperspectral images collected using the SisuROCK system were used to develop an automated methodology for generating kimberlite dilution maps. Smoothed and denoised images from two Snap Lake (Northwest Territories, Canada) kimberlite drill cores were processed, and SWIR and LWIR spectral endmembers were extracted from the images with each mineralogical endmember assigned to one of four compositional groups: undiluted kimberlite, microdiluted kimberlite, micro- and macrodiluted kimberlite, and crustal rocks. These endmembers were used to classify the SWIR and LWIR images, and the results were validated using linescan data, drill core logs, petrology reports, and the results of X-ray diffraction, Raman spectroscopy, and Micro-Fourier Transform Infrared (FTIR) spectroscopy. This study demonstrates that hyperspectral imagery can be used to generate dilution maps for hypabyssal kimberlites that far supersede other current techniques in terms of spatial resolution.

Reflectance spectrometers with automated scanning capabilities can be employed to gather compositional information directly from the surface of drill core. The usefulness of the technique is illustrated in the analysis of 300 m of drill core from the Olympic Dam iron oxide copper-gold (IOCG) deposit in South Australia which were scanned using HyLogger. The reflectance spectra were analysed to identify haematite and phengite, 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 corresponded to Fe concentration, and the intensity of the most intense absorption feature between 2 190 and 2 230 nm corresponded to Al. Phengite located near the ore-bearing zone was found to contain more Al than phengite located in the barren rocks, and this difference was observable in the reflectance spectra between 2 190 and 2 230 nm., Reflectance spectrometers with automated scanning capabilities can be employed to gather compositional information directly from the surface of drill core. The usefulness of the technique is illustrated in the analysis of 300 m of drill core from the Olympic Dam iron oxide copper-gold (IOCG) deposit in South Australia which were scanned using HyLogger. The reflectance spectra were analysed to identify haematite and phengite, 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 corresponded to Fe concentration, and the intensity of the most intense absorption feature between 2 190 and 2 230 nm corresponded to Al. Phengite located near the ore-bearing zone was found to contain more Al than phengite located in the barren rocks, and this difference was observable in the reflectance spectra between 2 190 and 2 230 nm.