Anglo-Australian mining and resources giant BHP Billiton reported its copper production slipped 12% to 271,100t in the three months ended December 31, the second quarter of the company’s 2010 fiscal year. The drops were a result of a strike at the Spence mine in Chile that cost the company some 28,000t and an incident at Olympic Dam in Australia that reduced output by roughly 20,000t, the company said in a statement.