Formation of Clayey Mineral
The soil particle it may be a part of mineral or any rock element. A mineral is generally a chemical compound which formed in nature automatically during a geological process, whereas a rock element has a combination of one or more different type minerals. Based on the nature of molecules, minerals are classified as silicates, aluminates, oxides, carbonates and phosphates etc.
Out of these mineral element, silicate group of minerals are the most important elements as they influence the properties of clay type soils. Different molecular arrangements of atoms or molecules in the silicate minerals give rise up to the different silicate structures.
Basic Structural Units of minerals:
The soil minerals are naturally formed by two basic structural units or molecular components:
- tetrahedral type
- octahedral type
- Considering the total valencies of the atomsor molecule forming the crystal units, it is now very much clear that the units are not electrically neutral condition and as such it does not exist as an single units.
The basic mineral units which combine with each other to form the sheets in which the oxygen or hydroxyl ions are shared among adjacent mineral units. These three types of sheets are then formed naturally, which namely as silica sheet, gibbsite sheet and brucite sheet.
Definition of Isomorphous substitution of minerals:
It is the replacement of the central atom or molecule of the tetrahedral or octahedral crystal minerals unit by another atom during the formation of the sheets of clayey minerals.
The clayey sheets then combine to each other to form various it may be two-layer or three-layer sheet natural clayey minerals. As the basic units of clay minerals are like sheet-type structures, the particle which formed from stacking of the basic mineral units is also plate-type. As a result of this, the surface area per unit mass of minerals becomes very large type.