​Rocks

On the basis of origin, and mode of formation, rocks may be classified into:

  1. Igneous,
  2. Sedimentary, and
  3. Metamorphic.

1. Igneous Rocks

  • These Rocks are formed by the cooling and solidification of molten silicate minerals (magma).
  • Igneous rocks include volcanic and plutonic rocks. These rocks are classified on the basis of texture and composition.
  • The major kinds of igneous rocks are Basalt, Gabbro, Andesite, Diorite, Rhyolite and Granite.

They are further classified on several other grounds as mentioned below:

I.On the basis of Silica Content

  1. Acidic Igneous Rocks have more silica e.g. Granites, Quartz and Feldspar.
    • These rocks have lesser contents of heavier minerals. Hence they are ....
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