Coastal deposits of heavy mineral sands; Global significance and US resources

Ancient and modern coastal deposits of heavy mineral sands (HMS) are the principal source of several heavy industrial minerals, with mining and processing operations on every continent except Antarctica. For example, HMS deposits are the main source of titanium feedstock for the titanium dioxide (TiO₂) pigments industry, obtained from the minerals ilmenite (Fe₂+TiO₃), rutile (TiO₂) and leucoxene (an alteration product of ilmenite). HMS deposits are also the principal source of zircon (ZrSiO₄), from which zirconium dioxide (ZrO₂) is obtained for uses mostly in refractory products. Sometimes monazite [(Ce,La,Nd,Th)PO₄] is recovered as a byproduct mineral, sought for its rare earth elements and thorium (Ault and others, 2016; Sengupta and Van Gosen, 2016; Van Gosen and Tulsidas, 2016).