In search of the forgotten rare earth

Abstract

Scandium (Sc) has been called a ‘miracle metal’. When alloyed with aluminium, it produces super-strong but lightweight materials, just right for use in the next generation of aeroplane manufacture and other high-tech applications. By definition, Sc is a member of the 17-strong, rare earth element (REE) family. Like the other REEs, Sc isn’t actually rare in terms of distribution—it can be found throughout Earth’s crust and has a similar abundance to lead—but unlike lead, economic concentrations of Sc are very rare, making it one of the most expensive elements in the world. Indeed, concentrations of Sc are usually so low that Sc is often excluded from geological assessments of REE—it is the forgotten rare earth.

But this may be about to change. Several research groups are turning their attention to Sc, using new data from exploration projects to identify a number of promising sources that could be mined. Here we discuss the behaviour of Sc and the distribution of these deposits worldwide. We argue that with improved understanding of how Sc associates with clinopyroxene and how it concentrates within weathering and waste products, such as laterites and red muds, these newly identified deposits could create a virtuous circle of raw materials supply and new high-tech uses.