Scandiferous Laterite

Scandiferous laterites form when mafic and ultramafic rocks (e.g. dunite, peridotite) undergo intense tropical or subtropical chemical weathering. Scandium, which substitutes for iron and aluminum in the host rock minerals, becomes concentrated in the residual laterite and saprolite horizon as the more mobile elements are leached away. The result is a soft, clay-rich ore that is amenable to atmospheric acid leaching rather than hard-rock blasting and grinding. The Nyngan deposit in New South Wales, Australia is the world's pre-eminent example, with grades reaching 300-400 ppm Sc2O3 in the oxide zone — among the highest known. Unlike polymetallic ore types where scandium is a byproduct, scandiferous laterites can justify scandium as the sole economic target.