Newly released core could hold clues on potential mineral prospectivity in Perthshire

More than 700 additional geological samples from the vicinity of the ceased Foss Mine near Aberfeldy, Perthshire, are now available for study at the National Geological Repository (NGR), located at BGS’s headquarters near Nottingham. The sample set, comprising outcrop and drillcore, was originally collected in the 1980s by Dr Norman Moles, who was undertaking research on the Foss deposit for his PhD at the University of Edinburgh. The samples complement existing NGR holdings of runs of drillcore from exploration drilling of the Foss and Ben Eagach–Duntanlich baryte deposits in the 1980s.

The fully catalogued collection of 717 specimens will be of interest to scientists for a range of further studies. Such studies could include investigations of critical metal potential, following a 2023 report by BGS that highlighted the central Perthshire region as one of the UK’s prospective areas for critical raw materials. The mine was the main source of baryte, or barium sulfate (BaSO₄), in the UK from the early 1980s until its closure in 2021. Baryte is primarily used in the oil and gas industry to help stabilise boreholes during drilling and was extensively used in the North Sea. Associated with the bedded baryte deposits are rocks rich in barium feldspars and micas, as well as sulfide and carbonate minerals.

Alongside the Foss material, the NGR houses the UK’s foremost collection of geological samples. This includes over 16 million geological specimens, including 600 km of drillcore and 200 000 thin sections. Boreholes take time to drill and can be very costly, so a shared repository of ground information, such as the collection held within the NGR, provides scientists access to pre-drilled samples for further research and analysis, saving significant project costs and accelerating timelines. The core from the site of the former Foss Mine is another example of how our relationship with the subsurface is ever evolving, sometimes in ways that can be hard to predict.

Cores from the Foss Mine, once used for the oil and gas industry, could now be a valuable resource for future research, potentially holding the secrets of critical mineral prospectivity that are essential for the clean energy transition.

Mark Fellgett, NGR facility lead at BGS.

Beyond mineral prospectivity, the nature of the rock formations in this region holds wider scientific value. Due to its age dating back to the Ediacaran Period of the Precambrian, approximately 539 to 635 million years ago, the material can also be used to study a marine environment that was very different to the present.

The core could be used for stratigraphical studies of the Ediacaran Period following the ‘snowball Earth’ of the Marinoan glaciation [at least 654.5 million years ago]. Analytical techniques developed since my PhD research, such as transitional metal stable-isotope analysis and laser ablation inductively coupled plasma mass spectrometry, could be applied to gain further knowledge of the hydrothermal processes and local and global environments at this pivotal time in the Earth’s history.

Dr Norman Moles.

BGS is progressively scanning and digitising the NGR collections and some of them are now available online. The GeoIndex is an easy-to-use, searchable map interface that enables users to find all data and information held by the BGS for any part of the UK, both onshore and offshore.

To arrange a visit to access this material, go to the accessing the NGR material collections page. You can also download the electronic resources accompanying the Foss Mine deposit.  

For general enquiries, please contact BGS Enquiries (enquiries@bgs.ac.uk) or call 0115 936 3100.