The Kaduna River, a tributary of the Niger River, flows roughly east to west through the center of the state. The state’s natural plant life is mostly Sudanian Savanna. This plant life is mostly made up of short trees, shrubs and several types of grass. The soil in Kaduna consists mostly of loam. Clay can also be found in this area. Native minerals include serpentine, asbestos, amethyst, kyanite, and gold. Graphite and sillimanite graphite can also be found here. This is an important raw material used in the manufacture of pencils, crucibles, electrodes, generator brushes and other parts.