Open Pit Mining
Open-pit diamond mining, also known as "open-cast mining" (top of page, center) is a method of extracting rock and minerals from the earth by removal from a machine-dug open pit or burrow. Open pit mines are typically used when mineral deposits are found close to the surface or along defined kimberlite pipes.Open pit mining is used when the surface material (overburden) covering the deposit is relatively thin and/or the desired minerals are imbedded within structurally unstable earth (cinder, gravel, or sand) that is unsuitable for tunneling. Small "pit lakes" tend to form at the bottom of open-pit mines as a result of groundwater intrusion.