In the summer of 2018 I had the good fortune to visit Dr. Nigel Brand of Geochemical Services Inc. in Kalgoorie, Western Australia. Kalgoorie is one of my favorite places on earth, famous for natural acid saline lakes, historic downtown and the awe-inspiring super pit. Nigel and his team of “spectral geologists” were undertaking a major core scanning and RC chip analysis project at their field headquarters. I reached out to Dr. Brand during the summer of 2020 to ask him about that project. This conservation has been edited for brevity and clarity.
J. Knapp: Nigel, I had the chance to visit your operations in Kalgoorlie and one of the things that I found so impressive was that you were using many different technologies for core scanning. Can you tell me what methods you are using for core characterization?
Dr. Brand: We were investigating an LCT-pegmatite deposit with the purpose of developing a geometallurgical model and trialing different technologies which could be implemented during mining. We have routinely used the Titan 800 with a custom calibration that provides a Li index to aid in exploration and to investigate the element distribution through the core. That study proved-up portable Raman spectroscopy with the Bruker BRAVO to identify the white minerals, and portable FTIR spectroscopy with the Bruker ALPHA (probably the most understated spectral instrument on the market) to quantify other minerals, and SWIR to detect weathered clays and iron oxides. We also had six samples scanned by Bruker’s micro-XRF (M4 TORNADO) at the Colorado School of Mines.
J. Knapp: What type of information is each method giving you?
Dr. Brand: The Titan 800 gave us chemistry down the drill hole, the BRAVO (Raman) and ALPHA (FTIR) confirmed mineralogy using a two systems approach, and the SWIR provided information of the depth of weathering. We have developed an internal library where we have characterized the LCT mineralogy, and that is critical for each project. The micro-XRF scans provided information on geological processes. Most importantly each instrument gave us a spectral file containing the “DNA” of a sample which can be used in machine learning processes.
J. Knapp: I love you call your geologist “Spectral Geologists.” It makes them sound like a team of superheroes. But they kind of are superheroes, as they use spectral vision to gather more information than a geologist alone could. Can you tell me how your Spectral Geologists are transforming all that data into useable information for exploration? Can you elaborate on how this can impact exploration?
Dr. Brand: We could build a geological (and geomet) model of the deposit based on the chemistry and mineralogy which highlighted potential extensions to the mineralization. In the process, we were able to develop work flow methodologies for identifying critical Li-bearing mineral in the deposit using the RAMAN. We even had a 24-hour turnaround grade control program for mining using the Titan 800 with a custom cesium calibration. The micro-XRF scans of the main Cs ore mineralogy (pollucite) showed its breakdown during weathering and key secondary minerals, verified by CSIRO, that need to identify in the weathered environment for the discovery of new and additional resources.
J. Knapp: What sort of data quality and QA/QC measures have you implemented?
Dr. Brand: For the TITAN 800 chemistry, we regularly scan known certified reference material and 1 in 33 samples was analyzed with laboratory assay (Fusion XRF). Those knowns turned up 2-4 weeks after drilling, but we could use them to check and recalculate the data for further exploration. For the BRAVO raman and ALPHA FTIR we used in-house standards that were verified by XRD.
J. Knapp: Has this work resulted in additional discoveries? ‘
Dr. Brand: Yes, during routine soil sampling the Li-index on the TITAN 800 identified several low order anomalies which were field inspected and rock chipped. The pRaman used on the rock chips identified holmquistite and spodumene on previously unexplored ground. This resulted in the Cade discovery.
J. Knapp: Nigel, thank you so much for speaking to us about this project. It has been so exciting to be in mining technology as innovators like you have brought so much innovation to the core scanning space. Dr. Brand is associated with Portable Spectral Services in Perth Australia, a Bruker distribution channel for Australia.