 He joined the Army to fight in the Civil War and returned after his father had failed to discover gold in the Vermillion or Mesabi Mountain Ranges.The black "banded ore" rocks that his father brought back to Duluth from the Mesabi Range convinced Leonidas to explore the Mesabi Mountains.Mesabi is an Indian word meaning "the grandmother of them all," that divides the water flowing into the Hudson Bay from the water flowing into Lake Superior.