There are two important differences between costs incurred up to the split-off point in joint product situations and those indirect costs incurred for products that are produced independently. First, certain costs such as direct materials and direct labor, which are directly traceable to products when two or more products are separately produced, become indirect and indivisible when used prior to the split-off point. For example, if ore contains both iron and zinc, the direct material itself is a joint product. Since neither zinc nor iron can be produced alone prior to the split-off point, the related processing costs of mining, crushing, and splitting the ore are also joint costs. Second, manufacturing overhead becomes even more indirect in joint product situations. Consider the purchase of pineapples. A pineapple, in and of itself, is not a joint product. When pineapples are purchased for canning, however, the initial processing or trimming of the fruit results in a variety of products (skin for animal feed, trimmed core for further slicing and dicing, and juice). The processing costs to the point of split-off, as well as the cost of the original pineapples, are mutually beneficial to all products produced to that point. Both of these phenomena are caused either because the material itself is a joint product or because processing results in the simultaneous output of more than one product.