Secondary mineral formation — such as the formation of clays — can counteract the alkalinity addition associated with rock weathering. It therefore must be considered if drawdown is being estimated on the basis of direct observation of mineral weathering rather than via estimation of alkalinity run-off. Secondary mineral formation depends on many factors, including on the type of primary mineral dissolving as well as the local climate and biota present. It can be characterized via soil mineralogy techniques like x-ray diffraction.