Clay mineralogy is an essential portion of soil mineralogy. Clay are constituted from some essential group of very small particles in crystalline form of which one/more member fall in these group are termed as clay minerals. These minerals are of hydrous-aluminum silicates with some exceptions where aluminum from some minerals can be substituted by magnesium and iron. Sometimes alkaline earth present in them as an essential constitutes. The clay mineral groups are:
We will discuss each of these groups and other groups not listed here also.
The character tics of clay minerals are governed by some properties they are also follows:
a. They have a layered structure of which one of the dimensions is in nanometer range:
1. Thickness of 1:1 layer=0.7 nm
2. Thickness of 2:1 layer= 1nm
b. Anisotropy remains in particles or layers
c. Surfaces of several types are exist in their structure
d. Plasticity is the one of the main properties of clay mineral we will learn how water is absorbed in clay interstices in the next posts.
e. Under firing drying they become harden. Although most clay minerals show this property, some exceptions are also available.