▁total ▁about ▁ 1 . 9 ▁billion ▁t onnes . ▁Lar ge ▁depos its ▁are ▁in ▁Australia , ▁Canada ▁and ▁the ▁United ▁States ▁with ▁the ▁largest ▁res erves ▁in ▁Iran . ▁At ▁the ▁current ▁rate ▁of ▁consumption , ▁these ▁res erves ▁are ▁estimated ▁to ▁be ▁de ple ted ▁som etime ▁between ▁ 2 0 2 7 ▁and ▁ 2 0 5 5 . ▁About ▁ 3 4 6 ▁million ▁t onnes ▁have ▁been ▁extracted ▁throughout ▁history ▁to ▁ 2 0 0 2 , ▁and ▁one ▁estimate ▁found ▁that ▁about ▁ 1 0 9 ▁million ▁t onnes ▁of ▁that ▁remains ▁in ▁use . ▁In ▁ 2 0 0 5 , ▁China ▁was ▁the ▁top ▁producer ▁of ▁mer cur y ▁with ▁almost ▁two - third s ▁global ▁share ▁followed ▁by ▁K yr gy z stan . ▁Several ▁other ▁countries ▁are ▁believed ▁to ▁have ▁un record ed ▁production ▁of ▁mer cur y ▁from ▁co pper ▁elect row in ning ▁processes ▁and ▁by ▁recovery ▁from ▁eff lu ents . ▁Because ▁of ▁the ▁high ▁to x icity ▁of ▁mer cur y , ▁both ▁the ▁min ing ▁of ▁c inn ab ar ▁and ▁ref ining ▁for ▁mer cur y ▁are ▁ha z ard ous ▁and ▁historic ▁causes ▁of ▁mer cur y ▁poison ing . ▁ ▁Production ▁Z inc ▁is ▁the ▁fourth ▁most ▁common ▁metal ▁in ▁use , ▁trailing ▁only ▁iron , ▁al umin ium , ▁and ▁co pper ▁with ▁an ▁annual ▁production ▁of ▁about ▁ 1 0 ▁million ▁t onnes . ▁World wide , ▁ 9 5 % ▁of