21. The new mine would be underground, with less impact on the environment than open pit mines . 22. The strike began Wednesday in the Kolubara open pit mine and spread Thursday to nearby Kostolac. 23. Open pit mining ended in 1976 when the pit reached a final depth of 300 m.24. Almost all the gold in Nevada comes from large open pit mining and with heap leaching recovery. 25. The deposit is essentially flat-lying at the surface, making open pit mining the extraction method of choice. 26. Early mining has shown that the deposit can be developed through a simple open pit mining process. 27. The district has rich lignite ( brown coal ) deposits, which is used in open pit mining . 28. By 1890, underground copper mining had started, and in 1907, Kennecott Copper Mine started open pit mining . 29. Both open pit mines are being operated in areas which used to have reclaimed for other uses. 30. In 1986, Coeur d'Alene Mines began large scale open pit mining operations on Nenzel Hill and beyond.
