Agriculture produces about 13% of the GDP and employs about 25% of the labour force. Commercial crop production, primarily on large farms, includes corn, sugarcane, wheat, seed cotton, tobacco, sorghum, and soybeans. The remaining land is made up of small farms raising subsistence crops, including corn, millet, peanuts (groundnuts), cassava, potatoes, dry beans, bananas, and oranges. Coffee and tea have been introduced in an effort to diversify crop production. The principal livestock include cattle, goats, and sheep. About half of the cattle are held by blacks practising traditional pastoralism. Zimbabwe has abundant mineral reserves. Gold, nickel, asbestos, coal, copper, chrome, iron ore, silver, and tin are produced. Manufacturing is fairly well diversified and includes crude steel, pig iron, cement, electrical and other machinery, cotton textiles, clothing, footwear, chemicals, plastics and rubber products.