According to National Geographic, TauTona is in the area of South Africa that has produced over half of all the gold that has ever been mined.
Between 3000 and 2700 million years ago, the Witwatersrand bodies of ore were deposited. The majority of the layers of ore are conglomerate with small stones of quartz and fine-grained silica-rich microcrystalline (chert) in a matrix of quartz grains and sulphides (primarily pyrite).
The layer of ore (from which the gold is mined) that extends from Johannesburg doesn't lie close to the Earth’s surface. It lies more or less at an acute angle below the surface. Furthermore the layer is only 25 cm thick. Nevertheless, the mine processes 140 000 tons of ore a month (with a yield of 1.6 tons of gold).
Three shafts exist as it is not possible to carry workers to the deepest depths of the mine. The journey down the shafts can take up to an hour even though the elevators or cages travel at 16 meters per second (57.6 km/h). The labyrinth of the tunnels that make up the mine collectively cover 800 km. A four hour commute awaits miners who work at the deepest parts of the mine.
The mine experiences an average of 10 underground earthquakes a day. Geologists and engineers use geophones planted deep into the rock face to monitor this seismic activity.
In Setswana (language) TauTona means “great lion”.
References and further reading
National Geographic - Megastructures- TauTona, City of Gold (2005)