Answer:
Tar sands.
Step-by-step explanation:
Tar sands also called as oil sands, it is defined as the mixture of mostly clay, water, tar sand, and a molasses like substances known as bitumen. Bitumen is composed of hydrocarbons in liquid oil in same molecules, and it is mainly used for produce gasoline, and other petroleum products.
Extracting bitumen is significantly more difficult, and costlier compared to other extracting refining liquid oil. Common extraction method of bitumen includes surface mining.