Types and examples of igneous rocks

There are two basic types of igneous rocks i.e. Intrusive Igneous rocks and Extrusive igneous rocks. Intrusive igneous rocks are those, which crystallize below the earth’s surface, and remain buried until the earth’s surface is eroded, while extruded igneous rocks are those, which erupt onto the surface, where they cool quickly to form small crystals.

Origin of the Igneous Rocks

We can find the mineral composition of igneous rocks by means of studying the chemical composition of the magma from which the rock has been crystallized. Because there is a large variety of igneous rocks, thus it was originally thought an equally large variety of magma also existed. But the later research found out that

Formation of Igneous Rocks

Formation of Igneous Rocks: The igneous rocks are formed from the cooling and solidification of the Magma/Lava. The minerals and the chemical makeup of igneous rocks are important in order to understand their formation. Experimental studies of the crystallization sequence of minerals from a melt have helped greatly in understanding the origin of igneous rocks.

Mechanics of Intrusion

Source of Magma:  Magma is originated from the upper mantle, which lies just under the crust, and is nearly molten. A slight drop in pressure caused by dee faulting etc, completes the melting process. The basaltic magma originates in this manner, while the “granitic magma” can be produced in two ways: (a) from melting of

Forms of Igneous Bodies

The igneous material is of two types; one is extrusive, and the other is intrusive. The extrusive igneous bodies are formed from the magma poured out at the surface of the earth. The lava flows are examples of extrusive igneous material. While the igneous bodies are formed by the consolidation of magma at some depth

Structures of Igneous Rocks

Once the molten magma extrudes out, it is affected by several factors. These factors provide varied structures to the rocks on cooling. Some important factors are as under; (1). Flow Structures: Sometimes an igneous rock shows parallel or subparallel bands or streaks which are caused by the flow of magma or lava during cooling and