The definition of an open pit mine is "an excavation or cut made at the surface of the ground for the purpose of extracting ore and which is open to the surface for the duration of the mine's life." To expose and mine the ore, it is generally necessary to excavate and relocate large quantities of waste rock. This form of mining is generally used when commercially useful rocks or ores are found near the earth surface. Quarries that provide building materials are often considered to be a form of open pit mining. This form of mining is carried on in the selected area until the mine is exhausted of beneficial materials or when there is a danger of a cave in. Often the exhausted mines are converted into landfills or lakes depending upon the associated geographical factors. Twin Creeks Gold Mine in Nevada , USA is a classic example of open pit mining. In India, Hutti Gold Mine in Raichur district of Karnataka is an example of open pit mining.