The rare earth element deposit at Morro do Ferro was formed under supergene lateritic weathering conditions. The ore body consists of soft, clayey, saprolithic material derived from potassic regional rocks that are deeply brecciated, weathered, and hydrothermally altered. Locally, the ore body is crosscut by a discrete magnetite/goethite stockwork. The main rare earth mineral is bastnäsite, the same as at Bayan Obo and Mountain Pass.
Bastnaesite (REE Fluorocarbonate) is the main REE mineral, followed by Cerianite and Monazite in minor proportions.
