REE mobilisation processes during alkali granitoid weathering

Tropical weathering profiles in granitoid host rocks are, at present, the main global source of the HREE. Currently worked
ion absorption clay deposits in S.E. China are developed on REE mineral-bearing A-type and highly fractionated, high K,
calc-alkaline granites (Wang et al., 2014). The SoS:Rare consortium will investigate if more REE-enriched alkali granitoids
have greater potential to form easily leachable REE deposits in weathered profiles (WP2). A PhD student will work
alongside the main team to investigate the genesis, magmatic and post-magmatic evolution of protolith igneous rocks from
Madagascar, with a specific focus on the behaviour of the REE. The student will to investigate the mineralogical, textural
and geochemical evolution of REE-rich bedrock and weathered profiles, their relationship to biogeochemical processes and
groundwater chemistry, and the mineralogical hosts of the REE. The Cenozoic alkaline igneous province of North
Madagascar comprises both intrusive and extrusive igneous rocks, ranging in age from 50 Ma to recent. This project will
focus on the Ampasindava Peninsula, which contains four major intrusions of syenite and peralkaline granite (BGS-USGSGLW,
2008; Estrade et al. 2013), one of which underlies the area licenced by the Tantalus exploration company. This
intrusion has been shown to contain primary REE minerals such as eudialyte and nacareniobsite (Estrade et al. 2013),
which were formed by magmatic processes and subsequently altered during hydrothermal activity. The other three main
intrusions await detailed study and will offer subjects for this PhD. Training will be provided in solid and liquid phase trace
element analysis using XRF, ICP-MS and ICP-OES, mineralogical analysis using XRD, and SEM, all at the University of
Brighton, and microprobe and LA-ICPMS at SoS:RARE partner organisations. The student will liaise with the PD and other
researchers on this WP, and also with the team investigating the microbiology of weathered deposits (WP4).

SoS RARE research will have an immediate economic impact by improving the prospects for the security of supply of neodymium (Nd) and the key heavy rare earth elements (HREE). The proposal has engaged six core industry partners involved in the exploration and development of new REE mines who will benefit immediately by introduction of our new exploration models and improved techniques for mineral extraction. Processing of REE raw materials is currently a major bottle neck in the value chain, and development of better methods will have an immediate impact on REE supply concerns. This will make projects more economically viable and environmentally friendly, helping to ensure a more stable supply. The four consultant company partners will gain key expertise and experience in exploration and processing which they will spread out into the wider REE mining and processing industries.

The unstable supply and cost of REE remains a major issue for manufacturers that make up a substantial part of the UK economy. A more secure supply chain will allow these manufacturers to better plan their short and long term product development. The research team will provide information on primary supplies, the likely development of future mines and how the supply chain will develop.
REE supply is a global concern. The project will have a global reach, through the industry partners involved (based in and working in the UK, Greenland, Malawi, Namibia, Spain, Canada and Australia), the core research collaborators in Germany, USA, Canada, Brazil and South Africa and wider international network links to Japan, France, and Madagascar. Diversity of supply is the key. This research proposal will place the UK as a centre in REE expertise and at the forefront of critical metals development.

The critical metals issue is requiring changes in UK Government and European Union policy, including increased support for research on primary supplies, recycling of existing metal stocks and substitution. The impact of this research on the prospects for low environmental impact extraction of REE, diversity/security of supply and responsible sourcing will be directly relevant to future policy. The 'race' to engineer REE out of new technologies will be unnecessary and many new applications could be explored. Therefore major impact will occur at the policy level as the research guides the decision making in research funding and legislation for REE.

Few people had even heard of 'rare earths' until the issue of China restricting supply reached the news headlines in 2010, yet this family of elements are ubiquitous in digital and green technologies, from the slimmest mobile phones to giant wind turbines. We will exploit the realisation among the general public of the importance of REE towards their modern high technology life-style and demonstrate the importance of REE chemistry and geology. The REE are extremely interesting and ideal for creative and educational outputs to entertain and inform wider non-technical audiences. Encouraging the public, including school students, to learn more about REE in nature is a key part of our outreach programme.