Origin of Magnetite in the Zoned Ultramafic Complexes of Southeastern Alaska

Appreciable concentrations of titaniferous magnetite occur in several of the ultramafic complexes that are exposed along a linear belt 350 miles in length in southeastern Alaska. Four of the larger bodies, at Klukwan, Snettisham, Union Bay, and Duke Island, are of economic interest. Large magnetite concentrations (15–20 percent of the rock by volume) of very uniform grade occur in the hornblende pyroxenite units of these complexes.