Analytical results and associated sample and analysis metadata from the analysis of minerals in earth material samples.

Analytical results and associated sample and analysis metadata from the analysis of minerals in earth material samples.

We describe a vision for a national-scale heavy mineral (HM) map generated through automated mineralogical identification and quantification of HMs contained in floodplain sediments from large catchments covering most of Australia. The composition of the sediments reflects the dominant rock types in each catchment, with the generally resistant HMs largely preserving the mineralogical fingerprint of their host protoliths through the weathering-transport-deposition cycle. Heavy mineral presence/absence, absolute and relative abundance, and co-occurrence are metrics useful to map, discover and interpret catchment lithotype(s), geodynamic setting, magmatism, metamorphic grade, alteration and/or mineralization. Underpinning this vision is a pilot project, focusing on a subset from the national sediment sample archive, which is used to demonstrate the feasibility of the larger, national-scale project. We preview a bespoke, cloud-based mineral network analysis (MNA) tool to visualize, explore and discover relationships between HMs as well as between them and geological settings or mineral deposits. We envisage that the Heavy Mineral Map of Australia and MNA tool will contribute significantly to mineral prospectivity analysis and modeling, particularly for technology critical elements and their host minerals, which are central to the global economy transitioning to a more sustainable, lower carbon energy model. The full, peer-reviewed article can be found here: Caritat, P. de, McInnes, B.I.A., Walker, A.T., Bastrakov, E., Rowins, S.M., Prent, A.M. 2022. The Heavy Mineral Map of Australia: vision and pilot project. Minerals, 12(8), 961, https://doi.org/10.3390/min12080961

Collection of mineral, gem, meteorite, fossil (including the Commonwealth Palaeontological Collection) and petrographic thin section specimens dating back to the early 1900s. The collection is of scientific, historic, aesthetic, and social significance. Geoscience Australia is responsible for the management and preservation of the collection, as well as facilitating access to the collection for research, and geoscience education and outreach. Over 700 specimens from the collection are displayed in our public gallery . The collection contains: • 15,000 gem, mineral and meteorite specimens from localities in Australia and across the globe. • 45,000 published palaeontological specimens contained in the Commonwealth Palaeontological Collection (CPC) mainly from Australia. • 1,000,000 unpublished fossils in a ‘Bulk Fossil’ collection. • 250,000 petrographic thin section slides. • 200 historical geoscience instruments including: cartography, geophysical, and laboratory equipment." <b>Value: </b>Specimens in the collection are derived from Geoscience Australia (GA) surveys, submissions by researchers, donations, purchases and bequests. A number of mineral specimens are held on behalf of the National Museum of Australia. <b>Scope: </b>This is a national collection that began in the early 1900s with early Commonwealth surveys collecting material across the country and British territories. The mineral specimens are mainly from across Australia, with a strong representation from major mineral deposits such as Broken Hill, and almost 40% from the rest of the world. The majority of fossils are from Australia, with a small proportion from lands historically or currently under Australian control, such as Papua New Guinea and the Australian Antarctic Territory.

Remotely sensed datasets provide fundamental information for understanding the chemical, physical and temporal dynamics of the atmosphere, lithosphere, biosphere and hydrosphere. Satellite remote sensing has been used extensively in mapping the nature and characteristics of the terrestrial land surface, including vegetation, rock, soil and landforms, across global to local-district scales. With the exception of hyper-arid regions, mapping rock and soil from space has been problematic because of vegetation that either masks the underlying substrate or confuses the spectral signatures of geological materials (i.e. diagnostic mineral spectral features), making them difficult to resolve. As part of the Exploring for the Future program, a new barest earth Landsat mosaic of the Australian continent using time-series analysis significantly reduces the influence of vegetation and enhances mapping of soil and exposed rock from space. Here, we provide a brief background on geological remote sensing and describe a suite of enhanced images using the barest earth Landsat mosaic for mapping surface mineralogy and geochemistry. These geological enhanced images provide improved inputs for predictive modelling of soil and rock properties over the Australian continent. In one case study, use of these products instead of existing Landsat TM band data to model chromium and sodium distribution using a random forest machine learning algorithm improved model performance by 28–46%. <b>Citation:</b> Wilford, J. and Roberts, D., 2020. Enhanced barest earth Landsat imagery for soil and lithological modelling. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

<div>The National Geochemical Survey of Australia (NGSA) is Australia’s only internally consistent, continental-scale geochemical atlas and dataset. The present report presents additional mineralogical data acquired as part of the Heavy Mineral Map of Australia (HMMA) project on the NGSA samples, covering ~81% of Australia. The HMMA project, a collaborative project between Geoscience Australia and Curtin University underpinned by a pilot project establishing its feasibility, is part of the Australian Government-funded Exploring for the Future (EFTF) program.</div><div>All of the 1315 NGSA bottom catchment outlet sediment samples, taken on average from 60 to 80 cm depth in floodplain landforms, were used in the HMMA project. The samples were dried and sieved to a 75-425 µm grainsize fraction, and the contained heavy minerals (HMs; i.e., those with a specific gravity > 2.9 g/cm3) were separated by dense fluids and mounted on cylindrical epoxy mounts. After polishing and carbon-coating, the mounts were subjected to automated mineralogical analysis on a TESCAN® Integrated Mineral Analyzer (TIMA). Using scanning electron microscopy and backscatter electron imaging integrated with energy dispersive X-ray analysis, the TIMA identified 163 unique phases (including ‘Unclassified”) in the NGSA sample set. The dataset, consisting of over 145 million individual mineral grains, was quality controlled and validated by an expert team. The data released here can be visualised, explored and downloaded using a free online, bespoke mineral network analysis (MNA) tool built on a cloud-based platform. Preliminary analysis suggests that zinc minerals and native elements&nbsp;(e.g., native gold and platinum) may be useful in mineral exploration applications. Detailed interpretations of the HMMA dataset will be provided elsewhere. Accompanying this report are data files of TIMA results, a minerals property file, and an atlas of HM distribution maps. </div><div>It is hoped the comprehensive dataset generated by the HMMA project will be of use to mineral exploration and prospectivity modelling around Australia, as well as have other applications in earth and environmental sciences.</div>

Brumbys 1 was an appraisal well drilled and cored through Brumbys Fault at the CO2CRC Otway International Test Centre in 2018. The Otway Project is located in South West Victoria, on private farming property approximately 35 km southeast of Warrnambool and approximately 10 km northwest of the town of Peterborough. Total measured depth was 126.6 m (80 degrees). Sonic drilling enabled excellent core recovery and the borehole was completed as a groundwater monitoring well. Brumbys 1 cores through the upper Hesse Clay, Port Campbell Limestone and extends into the Gellibrand Marl. This dataset compiles the extensive analysis undertaken on the core. Analysis includes: Core log; Foram Analysis; Paleodepth; % Carbonate (CaCO3); X-Ray Fluorescence Spectrometry (XRF); Inductively Coupled Plasma Mass Spectrometry (ICP-MS); X-Ray Diffraction (XRD); Grain Size; Density; Surface Area Analysis (SAA); Gamma. Samples were taken at approximately 1-2 m intervals.

<div>A novel method of estimating the silica (SiO2) and loss-on-ignition (LOI) concentrations for the North American Soil Geochemical Landscapes (NASGL) project datasets is proposed. Combining the precision of the geochemical determinations with the completeness of the mineralogical NASGL data, we suggest a ‘reverse normative’ or inversion approach to calculate first the minimum SiO2, water (H2O) and carbon dioxide (CO2) concentrations in weight percent (wt%) in these samples. These can be used in a first step to compute minimum and maximum estimates for SiO2. In a recursive step, a ‘consensus’ SiO2 is then established as the average between the two aforementioned estimates, trimmed as necessary to yield a total composition (major oxides converted from reported Al, Ca, Fe, K, Mg, Mn, Na, P, S, and Ti elemental concentrations + ‘consensus’ SiO2 + reported trace element concentrations converted to wt% + ‘normative’ H2O + ‘normative’ CO2) of no more than 100 wt%. Any remaining compositional gap between 100 wt% and this sum is considered ‘other’ LOI and likely includes H2O and CO2 from the reported ‘amorphous’ phase (of unknown geochemical or mineralogical composition) as well as other volatile components present in soil. We validate the technique against a separate dataset from Australia where geochemical (including all major oxides) and mineralogical data exist on the same samples. The correlation between predicted and observed SiO2 is linear, strong (R2 = 0.91) and homoscedastic. We also compare the estimated NASGL SiO2 concentrations with another publicly available continental-scale survey over the conterminous USA, the ‘Shacklette and Boerngen’ dataset. This comparison shows the new data to be a reasonable representation of SiO2 values measured on the ground over the same study area. We recommend the approach of combining geochemical and mineralogical information to estimate missing SiO2 and LOI by the recursive inversion approach in datasets elsewhere, with the caveat to validate results.</div><div><br></div><div>The major oxide concentrations, including those for the estimated SiO2 and LOI, for the NASGL A and C horizons are available for download, as CSV files. A worked example for five selected NASGL C horizon samples is also available for download, as an XLSX file.</div> <b>Citation:</b> P. de Caritat, E. Grunsky, D.B. Smith; Estimating the silica content and loss-on-ignition in the North American Soil Geochemical Landscapes datasets: a recursive inversion approach. <i>Geochemistry: Exploration, Environment, Analysis</i> 2023; 23 (3): 2023-039 doi: https://doi.org/10.1144/geochem2023-039 This article appears in multiple journals (Lyell Collection & GeoScienceWorld)

<div>Indicator minerals are those minerals that indicate the presence of a specific mineral deposit, alteration or lithology[1]. Their utility to the exploration industry has been demonstrated in a range of environments and across multiple deposit types including Cu-Au porphyry[2], Cu-Zn-Pb-Ag VMS[3] and Ni-Cu-PGE[4]. Recent developments in the field of SEM-EDS analysis have enabled the rapid quantitative identification of indicator minerals during regional sampling campaigns[4,5].</div><div>Despite the demonstrated utility of indicator minerals for diamond and base metal exploration in Canada, Russia and Africa, there are relatively few case studies published from Australian deposits. We present the results of an indicator mineral case study over the Julimar exploration project located 90 km NE of Perth. The Gonneville Ni-Cu-PGE deposit, discovered by Chalice Mining in 2020, is hosted within a ~30 km long belt of 2670 Ma ultramafic intrusions within the western margin of the Yilgarn Craton[6].</div><div>Stream sediments collected from drainage channels around the Gonneville deposit were analysed by quantitative mineralogy techniques to determine if a unique indicator mineral footprint exists there. Samples were processed and analysed for heavy minerals using a workflow developed for the Curtin University-Geoscience Australia Heavy Mineral Map of Australia project[7]. Results indicate elevated abundances of indicator minerals associated with ultramafic/mafic magmatism and Ni-sulfide mineralisation in the drainages within the Julimar project area, including pyrrhotite, pentlandite, pyrite and chromite. We conclude that indicator mineral studies using automated mineralogy are powerful, yet currently underutilised, tools for mineral exploration in Australian environments.</div><div>[1]McClenaghan, 2005. https://doi.org/10.1144/1467-7873/03-066 </div><div>[2]Hashmi et al., 2015. https://doi.org/10.1144/geochem2014-310 </div><div>[3]Lougheed et al., 2020. https://doi.org/10.3390/min10040310 </div><div>[4]McClenaghan &amp; Cabri, 2011. https://doi.org/10.1144/1467-7873/10-IM-026 </div><div>[5]Porter et al., 2020. https://doi.org/10.1016/j.oregeorev.2020.103406 </div><div>[6]Lu et al., 2021. http://dx.doi.org/10.13140/RG.2.2.35768.47367 </div><div>[7]Caritat et al., 2022. https://doi.org/10.3390/min12080961 </div> This Abstract was submitted/presented to the 2023 Australian Exploration Geoscience Conference 13-18 Mar (https://2023.aegc.com.au/)

Analytical results and associated sample and analysis metadata from the analysis of minerals in earth material samples.