Through the slow process of weathering, granite decomposes into very small fragments of igneous mineral when exposed to surface conditions. Weathering is the decomposition of rocks or minerals through either mechanical or chemical means. Mechanical weathering occurs when ice wedging or exfoliation affects the structure of granite, while chemical weathering causes rock erosion through processes like hydrolysis or oxidation.
Granite is an igneous type of rock that forms as hot magma cools and solidifies. Granite is hard and consists largely of quartz, feldspar, small quantities of mica and other minerals.
Decomposition of granite can take between 500 and 900 years. Two main types of mechanical weathering that affect granite are ice wedging and exfoliation. Ice wedging occurs through water seepage into rock cracks. When water freezes and thaws in these cracks, it can lead to granite breaking up into smaller fragments.
Exfoliation is the process through which layers of granite are peeled off. Chemical weathering causes changes in the minerals found in rock or granite. This can occur through oxidation or hydrolysis, where rocks are exposed to oxygen or water, respectively.