Classification of rocks

                 Classification of rocks 

Classification of rocks

 According to wikipedia, a rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition and the way in which it is formed.

  The building stone are classified in three way : -

1) Geological classification of rocks

a) Igneous Rocks

 All those rocks of the earth that have been formed by the natural process of cooling and solidification from hot and molten material (magma) are called igneous rocks. If magma solidifies on the surface of the earth basalt and traps are formed. If however the magma solidifies before reaching surface of earth, it forms granite.

b) Sedimentary Rocks

 These rocks are formed by the deposition of product of weathering on the pre existing rocks. All the products of weathering are ultimately carried away from their place of origin by the agent of transport such agent are wind, frost etc. The consolidation of the above product take place under pressure by heat or by chemical agent acting as a natural cement, limestone, sandstone belong to this group.

c) Metamorphic Rocks

These are originally either igneous or sedimentary that have undergone considerable changes in their shape, structure and sometimes even in their mineral composition. Under the influence of the agent of metamorphism that is heat and pressure. Quartz, marble, slat are the example of metamorphic rocks

2) Chemical classification of rocks 

a) Siliceous Rocks 

 These rocks have silica as their main component. They are hard, durable and not easily affected by weathering agent. Granite and quarsite are the examples of siliceous rocks.

b) Argillaceous Rocks

These rocks have Alumina clay as their main component. Although these rocks are dense, compact and hard. They are brittle and cannot stand with shocks. For examples, slate and laterite are the example of such rocks.

c) Calcareous Rocks

These rocks have calcium carbonate as  their main component. Limestone, marble etc are the example of calcareous rocks.

3) Physical classification of rocks 

a) Stratified Rocks 

These rocks causes possess planes of stratification or cleavage and such rocks can easily split up along these planes. For example sand stone, limestone and slate etc.

b) Unstratified Rocks 

 These rocks occur in huge masses without showing any layered structure in them. It cannot be easily split into thin layers. For example Marble and Granite.

c) Foliated Rocks

 These rocks have a tendency to be split up in a definite direction only. Foliated structure is very common in case of metamorphic rocks.