Kaolinite is a clay mineral that forms through the prolonged weathering of feldspar and other silicate minerals, especially in warm, humid climates. It is a 1:1 clay mineral, consisting of one silica layer bonded to one aluminum hydroxide layer, which gives it a relatively stable structure with little expansion or shrinkage as moisture changes.
Compared with many other clay minerals, kaolinite has a low cation exchange capacity (CEC), meaning it holds fewer nutrient ions for plant uptake. It is the dominant clay mineral in many highly weathered tropical soils, including Ferralsols and Oxisols, where it contributes to good drainage and stable soil structure but relatively low natural fertility.
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