Zambia’s copper production increased by 2.1% in the first half of 2015 versus the same period last year as mining companies in Africa’s No.2 producer of the metal ramped up output in May and June, the statistics office said on Thursday.

The majority of the copper deposits in Zambia are found along the “Copperbelt” a 500 million year old mountain chain. This mountain chain, the Lufilian Arc, formed when two large pieces of continental crust, the Kalahari craton and the Congo craton, collided. When it comes to the details of how mineralization occurred in this area, there is still considerable debate.

“Increase in copper production in May and June of 2015 was the main reason for the increased output,” the Central Statistical Office (CSO) said in a statement.

Somewhat similar styles of copper mineralization, variously containing gold, uranium and cobalt, are evident in the Domes Region to the west of the Copperbelt and are attractive exploration targets. Combined reserves and resources of copper-cobalt ore in operating mines of the Copperbelt exceed two billion tonnes and these have mostly been delineated for exploitation the after privatization of copper industry was completed.