4 . ▁It ▁was ▁once ▁Europe ' s ▁largest ▁and ▁rich est ▁gold ▁mine , ▁but ▁since ▁ 1 9 6 7 ▁the ▁mine ▁has ▁been ▁def unct . ▁ ▁M ines ▁Business ▁Area ▁M ines ▁conduct s ▁expl oration , ▁min ing ▁and ▁mill ing ▁operations ▁in ▁Sweden ▁and ▁Ireland . ▁Its ▁main ▁products ▁are ▁z inc ▁and ▁co pper ▁concent rate , ▁with ▁some ▁lead , ▁gold ▁and ▁silver ▁content . ▁The ▁goods ▁produced ▁are ▁sold ▁both ▁to ▁the ▁Group ' s ▁own ▁sm el ters ▁and ▁to ▁external ▁customers . ▁Bol iden ▁own s ▁and ▁oper ates ▁Europe ' s ▁biggest ▁z inc ▁mine ▁at ▁T ara ▁in ▁Ireland . ▁T ara ▁became ▁part ▁of ▁Bol iden ▁in ▁early ▁ 2 0 0 4 , ▁but ▁production ▁began ▁there ▁in ▁ 1 9 7 7 , ▁since ▁when ▁over ▁ 6 0 ▁million ▁t onnes ▁of ▁ore ▁have ▁been ▁m ined . ▁Bol iden ▁also ▁own s ▁Gar pen berg , ▁which ▁is ▁Sweden ' s ▁oldest ▁mine ▁still ▁in ▁operation . ▁M ining ▁at ▁Gar pen berg ▁began ▁back ▁in ▁the ▁ 1 3 th ▁century . ▁The ▁min eral - rich ▁Sk elle fte ▁field ▁lies ▁within ▁the ▁Bol iden ▁Area , ▁where ▁almost ▁ 3 0 ▁mines ▁have ▁been ▁opened ▁since ▁production ▁began ▁in ▁the ▁ 1 9 2 0 s ▁and ▁where ▁Bol iden ▁currently ▁oper ates ▁the ▁Ren ström ▁and ▁Krist ine berg ▁under ground ▁mines ▁and ▁the ▁Ma url iden ▁open ▁pit ▁mine .