mining engineering 332 history 87 ore deposits 34 uranium 26 mineral deposits 24 coal 22 crude oil 21 more ... natural gas 20 silver 19 deep mining 18 hard coal 16 brown coal 14 metallurgy 14 mining 14 ores 13 deposits mining 11 geological survey 11 gold 9 metallography 8 environment protection 8 environment 8 mine exploitation 7 economy 7 caustobiolite deposits 7 lead 7 environmental pollution 7 mineral processing 7 safety of work 6 business balance sheet 6 mines (mining) 6 less ...