Mining the Rocks
A rock mine is much easier to excavate than other types of mines. Rock mines begin as shallow pits and grow larger as the rock is withdrawn. These mines are mostly above ground level and are commonly about 60 feet deep. While quarries normally yield rocks, they also contain minerals.
When the mining goal is the production of dimension rock, excavation must be a painstaking effort to preserve the integrity of the rock. On the other hand, when mining gravel from a pit, explosives break up the rock before the trucks come in to claim the resulting stone.