Differentiate fixed costs and variable costs. 1  Total cost is the sum of fixed and variable costs.  Variable costs change according to the quantity of a good or service being produced. The amount of materials and labor that is needed for to make a good increases in direct proportion to the number of goods produced.
Xtrata is a top five producer of copper, thermal coal, coking coal, ferrochrome, zinc and nickel and has operations in 19 countries. The company's copper production in 2010 was over 900 thousand metric tons and it has copper facilities located in Australia, Chile, Peru, Argentina, and Canada.
Quadra Mining bought Robinson in 2004, and reopened the mine late that year. Since 2005, production has averaged about 125 million pounds of copper per year. In 2010, Robinson produced 109 MM lbs copper and 73,000 troy oz gold. In 2012, Quadra was acquired by KGHM Polska Miedz, a large Polish copper producer.