mining engineering history 90 ore deposits 34 uranium 26 mineral deposits 25 coal 25 crude oil 22 more ... natural gas 21 metallurgy 20 silver 20 deep mining 18 brown coal 18 mining 18 hard coal 16 deposits mining 14 ores 14 geological survey 11 mining law 11 gold 10 mineral raw materials 9 environment protection 9 foundry industry 9 mineral processing 9 caustobiolite deposits 8 deposit geology 8 metallography 8 lead 8 environment 8 safety of work 7 mines (mining) 7 less ...