Mining is the extraction of valuable minerals or other geological materials from the earth, usually from an ore body, lode, vein, seam, reef or placer deposit. These deposits form a mineralized package that is of economic interest to the miner. Excavation is the process of moving earth, rock or other materials with tools, equipment or explosives. It also includes trenching, wall shafts, tunnelling and underground. It is the preliminary activity of the construction project.