Which one of the following is not a type of chemical weathering?

Weathering is classified into physical, chemical, and biological processes [2]. Chemical weathering involves the alteration of rock composition through reactions with water and atmospheric gases [1]. Key chemical processes include carbonation (dissolving minerals in carbonic acid), hydrolysis (reaction with water to form new minerals), and oxidation (reaction with oxygen) [1]. In contrast, salt crystal growth, also known as haloclasty, is a mechanical or physical weathering process [2]. It occurs when saline solutions enter rock crevices and evaporate, leaving behind salt crystals that expand upon heating or crystallization [2]. This expansion exerts physical pressure on the rock structure, leading to granular disintegration without changing the chemical nature of the minerals [1]. Therefore, salt crystal growth is not a type of chemical weathering.

Sources

1. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Weathering > p. 83
2. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Salt Weathering > p. 85