A slagheap, also known as a spoil tip, boney pile, or gob pile, is a mountain of waste material left over from the mining process. This waste material typically consists of rock, dirt, and coal waste. The term "slagheap" is commonly used to describe this type of mountain of waste. However, there are other synonyms for slagheap that are equally descriptive, including slag pile, culm bank, and heapstead. Each of these terms is commonly used in the mining industry to describe the waste material that is left over after coal or other minerals have been extracted from the earth.