Open-pit mining
Open-pit mining refers to any large man-made hole in the ground from which rock or minerals are extracted. The term is used to differentiate this form of mine from those made by tunneling into the ground.Open-pit mines are made when large deposits of commercially useful minerals or rock are found near the Earth's surface. (A mineral is a chemical compound with a given composition and a defined atomic structure. A rock is a mixture of one or several minerals, in varying proportions.)
When minerals are found deep below the surface, a deep mine has to be dug to extract them. Open-pit mines usually keep getting deeper and wider until the mineral resource (or the plot of land owned by the mining company) is exhausted. When they are no longer used, open-pit mines are often used as landfill sites for the disposal of waste.
Some form of water control usually has to be used to keep the mine from becoming a lake.
Open-pit mines that produce building materials are more commonly referred to as quarries. Note: People in some English countries are less likely to make the distinction between this type of mine, and any other type of open-pit mine. Other specific types include strip mining.
Materials extracted from open-pit mines include:
- Clay
- Coal
- Gravel and stone (stone usually refers to bedrock, while gravel is unconsolodated glacial or fluvial deposits)
- Granite
- Gritstone
- Gypsum
- Limestone
- Marble
- Various types of metal ore
- Sand
- Sandstone
See also
- List of minerals and stone types
- List of stone
- List of open-pit mines