Lonmin, the world's third-largest platinum producer, is set to cut 6,000 jobs in South Africa due to falling prices and high production costs, the company said in a statement Friday.The cutbacks represent a huge reduction in Lonmin's workforce, which was 28,000-strong last year, and will add to South Africa's unemployment woes as the country struggles with weak growth.South Africa produces 70 percent of the world's platinum, and has been badly hit as prices have dropped 14 percent since May, and 45 percent since the start of 2011.