Primary rocks are formed at the first intense in the geological time scale this results that their is the formation of Lava Magma granite and many more substances. 

There are mainly three type of primary rocks.

Basalt – a fine granite exclusive Rock rich in Iron and magnesium commonly found in the volcanic areas and used in the road construction .

Granite – granite is a main part of quarts fields part and Mika widely used in construction.

Obsidian – it is a type of Rock which is formed by the cooled Lava used as a decorative purpo

se and as a cutting tool in a ancient civilization . 

Characteristics of primary rocks.

formation: they are the first Rock to be formed in the earth crust by the solidification of the Magma and Lava. 

Mineral composition : the specific minerals present in the primary rocks depend on the chemical composition of the original magma like that quartz fieldspar.

texture: primary rocks are exhibited a variety of the texture ranging from the fine granite to course granite the texture is a determinate by the rate of cooling of the Magma Rapid cooling result in the fine grained rocks while slow cooling leads to course grained rocks. 

interlocking structure: primary rocks typically have a interlocking crystalline structure when individual mineral grains are tightly interconnected these structure in hands The Rocks strength and durability. 

lack of fossils: primary rocks are formed from the molten materials and do not contain any fossils or organic remains they are generally devoid of any evidence of past life forms.

Conclusion

Primary rocks are important component of the earth crust and they play a vital role in understanding the geological history of the planet primary rocks can provide valuable insights into the formation of the Earth and the process that have shape the planet our time