The primary rock, or igneous rock, is the oldest type of rock, formed when molten lava or magma solidifies. They are dense, hard, and resistant to erosion and weathering and are of two types: volcanic and plutonic.

Types and Formation:

• The rapid process of solidification and crystallization on Earth’s surface with rapid cooling gives glass-like shape to the rocks, like the obsidian form.
• Plutonic rocks are formed when the magma cools down deceleratingly at great depths of the surface, like in granite and gabbro.
• If magma cools down at the surface level, it has a fine-grained composition and is called volcanic rocks like basalt and pumice.
• Metamorphic rocks are the preexisting rocks on the surface of the earth that go through climate change in terms of extreme heat and pressure that eventually differ the composition and structure of the rock.
• Accumulated sediments in the form of rocks, minerals, and organic matter form sedimentary rocks.

Conclusion:

The three types of primary rocks, igneous metamorphic and sedimentary, have different components and unique characteristics in them that are vital for the earth’s crust. If we study primary rocks, we will be able to get an insight into the geological history of our planet.