While physical weathering is most rapid in very cold or very dry environments, chemical reactions are most rapid where the climate is wet and hot. However, both types of weathering occur together, and each tends to accelerate the other. For example, frost weathering creates cracks in the surface of a rocky outcrop, making it more susceptible to chemical reactions by providing paths for water and air to penetrate the rock. The various weathering agents act in concert to convert primary minerals (feldspars and micas) to secondary minerals (clays and carbonates) and release plant nutrient elements in soluble form.