Igneous Rock Facts

Approximately 90 percent of the Earth's upper crust is made up of igneous rocks. Although this rock is found in abundance all over the planet, it is covered by a layer of sedimentary rocks and hence we don't get to see it until we hit the igneous rock bed while digging. These rocks, which are formed by the process of crystallization, have interlocked crystals which provide them with a strong and stable structure. This and other such igneous rock facts, make them one of the most sought after rock types in the world, since the ancient times.

Igneous Rock Etymology
One of the basic igneous rock facts is its etymology. The term igneous is derived from the Latin word 'ignis', which means of fire. Extrusive rocks, also known as the volcanic rocks, derive the name from the Roman god of fire - Vulcan, while intrusive rocks, also known as the plutonic rocks, derive the name from the Roman god of the underworld - Pluto.

Igneous Rock Types
As of now, around 900 different types of igneous rocks have been identified. The classification of these igneous rocks is based on the following factors

• Chemical composition of magma
• Temperature at which solidification takes place
• Speed at which cooling takes place

Two of the most common igneous rock types are basalt and granite, which cover most of the igneous rocks deposits on the planet. In most of the cases, igneous rocks in deep ocean floors are basaltic in nature, while the rocks in the continental mass are granitic in nature.

Igneous Rock Formation
Basically, igneous rocks are formed when molten lava turns to a solid form. This process by which the molten rock solidifies is known as crystallization. This lava is nothing but molten rock, which is referred to as magma when it lies beneath the Earth's crust. At times, the magma comes to the surface of the Earth, owing to some volcanic activity, and solidifies to become a rock referred to as extrusive igneous rock. In some cases, the magma seeps in between the layers of sedimentary rocks beneath the Earth's crust and starts cooling. The rocks formed by this method are referred to as intrusive igneous rock.

Igneous Rock Characteristics
The most common igneous rock characteristics are the size of the crystal and color of the rock. These crystals of varying size are interlocked into each other to give stability to the rock structure. On the other hand, the color of the igneous rocks varies from pink to black, depending on the mineral content of the rock. These rocks are strong, heat resistant, less radioactive and found in abundance on the planet.

Igneous Rock Identification
Igneous rock identification is not as difficult as it seems, you just need to get the basics right. You will have to memorize the texture, color, name of the minerals, etc. First of all, you will have to observe the texture of the rock specimen you have. It can be followed by identifying the minerals based on the color of the rock specimen. Being aware of different mineral combinations is always advantageous. The place where you have found the rock also plays a vital role in igneous rock identification.

These were some igneous rock facts which make these rocks one of the most commonly used rock type on the planet. From construction of buildings to interior designing, igneous rocks are used everywhere. Undoubtedly, various igneous rock characteristics play an important role in the popularity of these rocks. Each igneous rock variety has uses of its own, some are used for kitchen counters, while some for decorative purpose and some even to make jewelry.