The discovery of a boulder of high-grade iron ore by Leonidas Merritt in 1887 during a survey for the railroad, which he brought to Duluth, the Merritt brothers ("the Seven Iron Men") established the Mountain Iron Mine in 1892 Mountain Iron, Minnesota which represents the beginning of the exploitation of the Mesabi Range iron ore in the Iron Range of northeast Minnesota. By 1893 the Merritts had claims on a significant portion of the Mesabi Iron Range and had built the Duluth, Missabe & Northern Railway DM&IR. Financial conditions forced them sell their shares to John D. Rockefeller who later sold to Andrew Carnegie. The early development was as an underground mine, but open cast mining soon proved to be a better choice because of the soft, shallow ore deposits. The Mesabi Range and nearb