mining engineering 317 history 77 ore deposits 33 coal 23 crude oil 21 natural gas 20 mineral deposits 19 more ... silver 19 hard coal 16 deep mining 15 brown coal 15 metallurgy 14 mining 13 deposits mining 12 ores 12 geological survey 11 mining law 11 gold 9 caustobiolite deposits 8 metallography 8 environment protection 8 safety of work 7 mines (mining) 7 mine exploitation 7 economy 7 lead 7 mineral processing 7 business balance sheet 6 coal energy sources 6 metals 6 less ...