The increased production of higher-value ore, improved recoveries and improved metal pricing has positively impacted on Canadian company Sierra Metals’ Corona subsidiary’s results for the half-year. Corona, which is 80% owned by Sierra Metals and which mines for copper, lead, zinc, silver and gold at the Yauricocha mine, in Peru, earned net income of $21.6-million, or $0.60 a share for the six months ended June 30, a 1 046% rise on the net income of $1.9-million, or $0.05 a share, earned in the first half of 2016.