Editorial

Welcome to issue three of volume 128 of Applied Earth Science. This issue showcases some of the breadth of research published in Applied Earth Science and starts with a paper by Johannesson et al. (2019), who focus on a somewhat atypical use for basalt, the most common rock on Earth’s surface. The use of basalt as a building stone and aggregate is well known, but it can also be cast for use in industrial applications that make use of the natural characteristics of the stone. However, Johannesson et al. (2019) examine another potential use of basalt from Iceland in the form of material that can be used to generate continuous basalt fibres, a substance that has better physicomechanical properties than fibreglass but (given the right feedstock) is cheaper to produce than carbon fibre. Their research indicates that although no single Icelandic basalt sampled during their study is ideally suited for use as a basalt fibre feedstock, the addition of small amounts of CaO to some of their samples significantly improves the potential of these basalts, suggesting that Iceland may be capable of providing basalt that can be used in this manufacturing process.

The second paper in this volume outlines a potential addition to the mine planning toolbox by examining an unmanned aerial vehicle (UAV; sometimes known as drones) approach to lithological classification within an open pit phosphate mine in Brazil (Beretta et al. 2019). The authors assessed the viability of surface feature detection using visible light-based data and machine learning-based algorithms to generate a complete geological model for the mine. This model was then compared to a geological model obtained using traditional methods. The comparison indicated the usefulness of the UAV-based approach, which is not just quicker and potentially cheaper but is also safer than manual face mapping as operators do not need to be within the mine to acquire data. This is still an area that requires further research but this study outlines the potential use of this approach in moving towards more automated geological mapping systems.

Parnell et al. (2019) change the focus of the issue towards more traditional economic geology-type research and present the results of the analysis of gases trapped within sulphide minerals in a number of areas of Palaeozoic gold mineralisation in Britain and Ireland. These data indicate that mineralisation hosted by Carboniferous cover units contains less non-aqueous gas than mineralisation hosted by greenschist units. In addition, combining the gas data presented in the study with the results of fluid inclusion microthermometry suggests that organic species may have a role in the genesis of orogenic gold mineralisation in addition to suggesting a potential role for trapped gas analysis in mineral exploration.

The next paper in the issue provides an overview of the use of a mineral norm calculation in resource estimation, focusing on the Mississippi Valley-type (MVT) sulphide and non-sulphide Zn–Pb mineralisation of the Florida Canyon deposit, Peru (de Oliveira et al. 2019). The approach taken by de Oliveira and Saldanha (2019) uses the concentrations of Zn, Pb, and S to calculate the abundance of sphalerite, galena, and non-sulphide minerals within a block model, allowing the detailed examination of the geometry and spatial relationships between the sulphide and non-sulphide mineralisation within the deposit. Understanding these relationships is key, not just for furthering our knowledge of the mineralising system that formed this deposit but also for mine planning and mineral processing, given that sulphide and non-sulphide ore types require different types of processing. The simple algorithm outlined by the authors is easy and quick to use and provides an approach that can be used during mineral resource assessments involving mixed ore types; the application here is for MVT-type mineralisation but this style of approach may also have uses in other mineralising systems that contain different ore types (e.g. oxide and sulphide ores).

The penultimate paper in the issue outlines the geology of a Cu–Au skarn deposit within the Tien Shan belt of central Asia. Here, Abzalov et al. (2019) present new geochemical data for the deposit and suggest that the granitoids related to the Bozymchak Cu–Au skarn deposit are geochemically similar to high-K calc-alkalime magmatism associated with the Almalyk Cu–Au porphyry deposit some 130 km distant from the study area. The granitoids within this area are also geochemically zoned, suggesting that this zonation could be used as a vector during exploration for this type of skarn mineralisation.

Last, but by no means least, in this issue is a paper by Gaboury (2019) who provides an overview of the key parameters within orogenic gold systems. These deposits provide a significant proportion of global primary gold production and formed between the Archean and Phanerozoic at crustal depths typically >4 km. Gaboury (2019) uses a systematic approach to examine these mineralising systems from base to top, outlining key considerations in terms of fluid, ligand, and gold sourcing, the role of faults as conduits for mineralising fluids, and the processes involved in the precipitation of gold. This review also suggests that carbon- and pyrite-rich sedimentary rocks play an important role in the genesis of these deposits independent of their time of formation.

The breadth of the topics presented in this issues indicate the range of topics encompassed in the scope of the journal (https://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=yaes21) and I feel certainly fulfil our aim of serving an international readership based in industry, academia, and government. As always, comments and queries about the suitability of manuscripts are welcome; my email address is below and myself and the editorial team are always happy to discuss manuscript suitability prior to submission. See you in Issue 4!