The Difference Between

How do you distinguish between variable and permanent charge of clays in soils?


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May 28, 2013 11:28PM

Clays are phyllosilicates and have a sheet structure that is ionic in nature.


Mainly a permanent clay mineral is a 2:1 clay (which means that it has 2 layers of silica and one of aluminum hydroxide)

The permanent charged is nearly Always negative and exists by isomorphic reaction

A variable charged clay mineral can be both, 2:1 and 1:1 clay minerals (1:1 = one layer of silica on 1 layer of aluminum hydroxide)

a variable clay mineral can be either negative positive or zero