mining engineering history 90 ore deposits 34 uranium 26 mineral deposits 24 coal 23 crude oil 21 more ... natural gas 20 silver 19 deep mining 18 hard coal 16 brown coal 15 metallurgy 14 mining 14 ores 13 deposits mining 12 geological survey 11 mining law 11 environment protection 9 gold 9 caustobiolite deposits 8 metallography 8 environment 8 safety of work 7 mines (mining) 7 mine exploitation 7 economy 7 lead 7 environmental pollution 7 mineral processing 7 less ...