mining engineering 336 history 89 ore deposits 34 uranium 26 mineral deposits 24 coal 23 crude oil 21 more ... natural gas 20 silver 19 deep mining 17 brown coal 15 metallurgy 14 mining 14 ores 13 hard coal 13 deposits mining 11 geological survey 11 mining law 10 environment protection 9 gold 9 caustobiolite deposits 8 metallography 8 environment 8 mines (mining) 7 economy 7 lead 7 environmental pollution 7 mineral processing 7 business balance sheet 6 mine exploitation 6 less ...