Services is the biggest sector of Tanzania's economy and accounts for 40 percent of GDP, namely wholesale and retail trade (12 percent); public administration and defense (6 percent) and transport and storage (5 percent). The primary sector accounts for 30 percent of GDP, mainly due to crops production (18 percent). The industrial sector represents 28 percent of total wealth, namely manufacturing (6 percent) and mining and quarrying (5 percent) including natural gas, gold, diamonds, coal, iron ore, uranium, nickel, chrome, tin, platinum, coltan and niobium.