 The lower portion along the northwestern margin consists of ultramafic cumulates with associated segregations of nickel, copper and platinum group elements.Those metallic ores have attracted the interest of resource companies, and their attempts to mine are opposed by conservationists.Along its northern margin, the Duluth Complex adjoins older structures, the Archaen Ely Greenstones (once believed to be the oldest exposed rock on earth), and the ore-bearing Mesabi and Gunflint iron ranges deposited as part of the Animikie Group from the Penokean orogeny, a mountain-building event from Paleoproterozoic times.