Zimbabwe’s mining industry has appealed to the government for help, saying output is slumping as the state-owned power company fails to honour electricity-supply contracts. Zesa Holdings has broken its promise to “ring-fence” supplies to miners, Zimbabwe’s Chamber of Mines wrote in a letter last week to Finance Minister Mthuli Ncube. With some companies lacking power for three days a week, mineral production will fall by as much as 30% this year, it said.