city, Orenburg oblast (region), west-central Russia. It lies along the Ural River, in the Orsk-Khalilovo industrial district of the southern Urals. The centre of ferrous metallurgy in the area, the city has a major integrated iron and steel plant that was developed in the 1950s on the basis of nearby iron-ore deposits. Chemical production is also of importance. Pop. (2006 est.) 103,927.