Global distribution of material stocks: iron, copper and nickel Kenichi Nakajima, Ichiro Daigo, Keisuke Nansai, Kazuyo Matsubae, Wataru Takayanagi, Makoto Tomita and Yasunari Matsuno Matériaux & Techniques, 105 5-6 (2017) 511 Published online: 20 June 2018 DOI: 10.1051/mattech/2017040