In regions of very high rainfall, such as a tropical
rainforest, so much water seeps through the soil that it
leaches away nearly all the soluble cations. Only very insoluble
aluminum and iron minerals remain (Fig. 6–17c).
Soil of this type is called a laterite. Laterites are often
colored rust-red by iron oxide (Fig. 6–19). A highly aluminous
laterite, called bauxite, is the world’s main type
of aluminum ore