What is Magma Made of

Magma is the molten form of rock, stored deep beneath the Earth's surface. The temperature of this hot fluid can range from 1292° F to 2372° F. Tremendously hot, magma is capable of melting the surrounding rock structures to produce more magma. It can also escape to the surface of the Earth through volcanoes. The volcanoes emitting ash are termed as explosive volcanoes, while those which emit lava are termed as effusive volcanoes. The explosions in these volcanoes are attributed to the intense pressure that is formed due to various gases within the volcano.

How is Magma Formed

Temperature and pressure rises with depth, eventually reaching to a level wherein the strongest rock is melted and turned to a liquid form which is called magma. Enormous amount of heat that can make the rocks melt is also generated when two huge rock masses rub against each other. The molten material which already exists in the outer core of the planet travels to other parts through cracks and fissures. On its way it passes by the solid rock walls which are melted due to the heat that is emitted from the magma. Due to intense pressure, high temperature, density change and mixture of gases in the interior of the Earth, this molten rock material is pushed towards the surface of the Earth via cracks in the Earth's crust.

What is Magma Made Of

Magma is primarily made up of elements like oxygen, silicon, aluminum, iron, magnesium, titanium, calcium, sodium, potassium and phosphorous. As the amount of oxygen and silica in the molten matter is high, it is ideal to classify different types of magma depending on its silica content. Ultramafic, Mafic, Intermediate and Felsic are the four different types of magma, broadly categorized on the basis of their silica content.

Ultramafic magma is extremely low in silica, with less than 45% of it. But it is rich in heavier elements like iron and magnesium. This magma can have a temperature of about 2732° F, but has very low viscosity. Its eruptive behavior is considered to be gentle. Mafic magma is relatively poor in silica content, with just less than 50% of it, but rich in heavy elements like iron, magnesium and calcium. This low viscosity magma can have a temperature as high as 2372° F. It is very explosive in nature. Intermediate magma contains 60% silica, but the magnesium and iron content in it is very low. Very explosive in nature, its temperature can be as high as 1832° F. Felsic magma contains more than 70% silica content, but its iron and magnesium content is relatively negligible. Highly viscous, its temperature can be as high as 1652° F.

The composition of magma undergoes certain changes as it ascends to the surface. On its way up, the rising magma melts the rock structures surrounding the upward flow, integrating the elements which are present in these rocks. Such mixing produces an intermediate composition of magma. The viscosity of the magma is defined as its resistance to flow. It has a direct relationship with the silica content in the magma, i.e. more the silica content greater is its viscosity. The difference in composition of magma can also be attributed to the fact that a particular rock is melted in different temperatures at different depths, but this is a relatively rare phenomena.