The rare earth elements (REEs) or lanthanides (La-Lu) are a group of elements widely used in applications ranging from modern, everyday personal devices such as mobile phones to industrial scale e-tech/green facilities such as wind turbines. The heavy rare earth elements (HREEs, Gd-Lu)) are particularly in high demand as they occur in relatively low concentrations and yet are more widely used for TV phosphors, lasers and computer memories. We currently have a reasonably good understanding of the geological occurrences/associations of REEs but our ability to predict where economic HREE deposits occur and to develop low cost extraction technologies is hampered by lack of understanding of how REEs are transported, concentrated and fractionated (separation between light and heavy REE) as well as how host mineral stability ultimately controls extraction efficiency.

This project will bring together a core group of experienced geoscientists grounded in experimental studies of fluid-rock interaction (melts, hydrothermal fluids) with chemical spectroscopists, mineral physicists and industry end-users to engage in a study focussed on addressing key questions relating to transport, concentration and fractionation of REEs. This will be achieved by focussing on the following key questions:
(i) Why do we get REE enrichment? By conducting challenging but well constrained experiments simulating the reaction(s) of different fluids with REE-containing minerals, rocks and other compounds we will constrain partitioning and speciation of different REEs.

(ii) How does enrichment occur? Enrichment processes will be constrained by conducting absorption spectroscopic measurements of REEs in hydrothermal fluids to determine types and stabilities of the different REE species.

(iii) Where does enrichment occur? By carrying out structural characterisation of stable host REE mineral phases to determine crystallographic parameters that control REE occurrence and by performing theoretical calculations to predict which are the stable mineral structures consistent with spectroscopic measurements we will determine where enrichment occurs

The work will be carried out in two phases: A scoping study (catalyst phase) designed to build a research consortium that, through Science Innovation Workshops will appraise state of the art science backed by preliminary data collection and modelling to refine key questions for the development of a detailed application to the main phase of the funding round. The main research phase, if awarded will deliver novel experimental, micro-analytical and spectroscopic data plus structural modelling which will enhance significantly our ability to understand the distribution of economically exploitable HREE resources.

Potential Impact:
This catalyst stage proposal focuses upon developing a research consortium which will define the core research targets which must be addressed in order to provide a complete understanding of the fundamental processes controlling HREE mobility and mineralisation in the crust as a prerequisite for effective mineral exploration and processing. As a consequence its impact relates directly to the distribution, concentration, extractability and stable supply of critical metals essential for technological applications and e-tech applications. The list of direct and indirect stakeholders in this research is therefore considerable.

i) Academic beneficiaries are discussed in detail elsewhere, however, the research proposed underpins not only research into resource geology, but also fundamental research into the evolution of the Earth's crust and as a consequence the modern Earth surface environment which we experience.
ii) Industrial beneficiaries including consortium members and beneficiaries out-with the consortium will include companies involved in the exploration for HREE resources, their extraction and mineral processing. In particular any understanding of HREE mineralisation that leads directly to new exploration strategies and targets impacts directly upon the profitability of these organisations as well as the HREE supply chain. The direct involvement of production companies in the consortium leading to a main stage grant will foster close links between academia and industry.
iii) Understanding HREE mineralisation, and consequently identification of likely future resources, their size and ease of exploitation has downstream impacts for companies involved in HREE recycling as part of the industrial life cycle of HREEs. The style of HREE mineralisation exploited in the future is of interest to environmental consultants and policy makers especially where extraction is associated with the release of environmentally hazardous materials.
iv) The on-going security of supply of HREE materials, and consequently the stability of commodity prices for industrial end-users and manufacturing companies influences directly the profitability of those companies as well as having a direct influence upon product availability and price.
v) The critical role of HREEs in e-technologies including wind-turbines relates directly to energy and environmental policies dictated by national and international government policy and agreements including policies effectively mediated by the interaction of government and industry via NGOs. The stable of e-tech element is especially significant to the UK's future energy policy.
vi) The supply chain for E-tech elements such as HREEs impacts directly upon the price of consumer items, the cost of energy and governmental energy policy with direct consequences for the general public in the UK and worldwide. The involvement of the National Museum of Scotland and the Scottish Earth Science Educational Forum at the catalyst stage and a direct aim to participate in outreach activities is aimed at raising awareness of the importance of HREEs and the wider importance of critical element geology among the general public and through the Scottish schools' curriculum.