The Kuranakh epithermal gold deposit, East Russia

The Kuranakh mine is one of the largest lode gold mines in Russia and has produced 220 tonnes of gold. From 1957 until 1997 the mine has extracted 74.1 million tonnes of ore grading 3.57 g/t gold (Benevolskiy, 1985). The Kuranakh gold deposit is of the epithermal, quartz-adularia-sericite (illite)-type. Several subhorizontal, blanket- or ribbon-like ore bodies up to 50 m thick occur mainly along and/or above, and in some places, under the contact between Cambrian calcareous footwall rocks and overlying Jurassic clastic rocks within a narrow zone, about 30 km long, bounded by several south-north trending faults. Originally, gold mineralization was associated with pyrite, arsenopyrite, sphalerite, and galena; however, total sulfides were only a few percent of the total rock mass.The deposit has been thoroughly oxidized and only traces of arsenopyrite and pyrite are found. Gold occurs primarily as mineral grains less than 5 microns in size and is usually contained within friable grains of porous goethite. Studies of fluid inclusions show homogenization temperatures from 80oC to 220oC but generally averaging from 110 degrees C to 160 degrees C.