Thomas J. O’Neil, a native of Fredonia, New York, holds a B.S. in mining engineering from Lehigh University, MS from Penn State, and PhD from the University of Arizona.  Mr. O'Neil joined Cleveland-Cliffs Inc. in 1991 as Senior Vice President-Technical and advanced through several positions until his appointment as President and Chief Operating Officer in 2000, a position he held until his retirement in 2003.

Prior to joining Cliffs, Mr. O'Neil spent 10 years with Cyprus Minerals Company and its previous owner, Amoco Minerals Company, where he served in various capacities, including Vice President/General Manager, Cyprus Sierrita Corporation and Vice President of South Pacific Operations, stationed in Sydney, Australia. 

Prior to joining Amoco, Mr. O'Neil was professor and head of the Department of Mining and Geological Engineering at The University of Arizona.  Mr. O'Neil has been a member of SME for 60 years, serving as its President in 2003. He was elected to the National Academy of Engineering in 1999, the Southwest Mining Hall of Fame in 2003, and the National Mining Hall of Fame in 2022.  He is a former Director of several mining companies, including Homestake, Hecla, and Fording Coal.