Rainbow Rare Earths (AIM:RBW) has updated the Mineral Resource Estimate (MRE) for its Phalaborwa project in South Africa to include yttrium, which the company said reflects recent test work confirming its presence in the proposed SEG+ product. The element has been subject to Chinese export controls since April 2025.

Rainbow said the updated MRE indicates commercial quantities of all economically important medium and heavy rare earth elements (REE) at Phalaborwa, including dysprosium, terbium, samarium, europium, gadolinium and yttrium. The deposit also contains neodymium and praseodymium. The company described Phalaborwa as one of the relatively few projects capable of producing a broad suite of critical REE.

The inclusion of yttrium follows what Rainbow described as successful test work demonstrating that its planned SEG+ product will contain the full set of targeted medium and heavy REE. The company said this development comes at a time when Chinese export restrictions have created tighter market conditions and increased interest from potential off-takers.

Rainbow said Chief Executive George Bennett had noted rising attention from buyers since China implemented controls on several rare earth elements earlier this year. Bennett said shortages were emerging in restricted elements and that countries such as the US were placing greater emphasis on securing diversified REE supply chains.

The company said it intends to incorporate additional REE value into its economic modelling for the Definitive Feasibility Study, expanding beyond the neodymium, praseodymium, dysprosium and terbium assumptions used in earlier economic work. Rainbow said updated demand forecasts supported the broader approach.

The update aligns the project with the latest US Geological Survey 2025 List of Critical Minerals, which classifies all of Phalaborwa’s rare earths as critical. Rainbow said most of the REE at the project — excluding europium — fall into categories considered at higher risk of supply chain disruption.

Rainbow added that its Uberaba project in Brazil is also expected to produce significant SEG+ rare earths, which will be included in its ongoing economic assessment work.

China introduced export controls in April 2025 on samarium, gadolinium, terbium, dysprosium, lutetium, scandium and yttrium, as well as magnets containing these elements. Industry reporting has indicated that the measures have contributed to supply tightness in sectors such as automotive, robotics, drones and defence.