The Great Cobar ore deposit was discovered in 1870. Production commenced in 1871 and since that date mining at Cobar has been more or less continuous. The field has produced copper, gold, and silver to the value of approximately £A27,000,000. Cobar has been the most important producer of copper in New South Wales, and in recent years, has also been the most important gold-mining centre. The Zinc Corporation Limited is carrying out, with the aid of the Bureau, an extensive geological and geophysical examination of the area, with the hope of finding other orebodies. The Bureau itself has extended geological mapping over an area of approximately 2,000 square miles in the Cobar-Nymagee-Canbelego district with the ultimate aim of discovering other ore deposits, or even fields of the Cobar type. In the Nymagee district, North Broken Hill Limited is also carrying out, in co-operation with the Bureau, an extensive exploration programme. The history, production, reserves and prospects of the New Occidental, Chesney, and New Cobar mines are discussed in this report.