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.
The copper probably came from the Caucasus region more than 620 miles (1,000 kilometers) away. In ancient Egypt, people used copper alloys to make jewelry, including toe rings. Researchers have found massive copper mines from the 10th century B.C. in Israel. About two-thirds of the copper on Earth is found in igneous (volcanic) rocks.