Gold is often co-mined with copper, molybdenum and uranium. Main reserves of gold can be found in South Africa, Tanzania, Mali, Ghana, USA, Australia, Canada, China, Chile, Peru, and Brazil. Gold is extracted via large scale open pit mining or underground mining. Gold mining produces a large amount of waste. Up to 6 tonnes of rock must be processed to obtain one gram of gold. Cyanide or mercury are the most common substances used to extract gold from the rock. Between 78% and 85%% of gold is used for jewelry; the rest is used industrially or hoarded as a monetary reserve.