ocr: Crude oiland natural gas, Algeria's main resources, were first producedin the 1950s. Algeria also has diverse minerals,including iron ore, zinc, silver, copper ore and phosphates. In the 1960s and1970s, Algeria sought to become a manufacturing country, with investments in building materials, retined products and steel; none ofthese sectors is competitive in world markets. Although agriculture employs one-quarter of Algeria's work force, its importance to the economy 1S diminishing. State forests cover some 2% of. Algeria's land. Most are brushwood,but some areas include cork oak trees, Aleppo ...