mining engineering 336 history 84 ore deposits 30 uranium 26 mineral deposits 24 coal 23 crude oil 21 more ... natural gas 20 deep mining 17 hard coal 16 brown coal 15 metallurgy 14 mining 14 deposits mining 12 ores 12 silver 12 geological survey 11 mining law 11 environment protection 9 gold 9 caustobiolite deposits 8 environment 8 safety of work 7 mines (mining) 7 mine exploitation 7 economy 7 environmental pollution 7 mineral processing 7 business balance sheet 6 coal energy sources 6 less ...