MINERALS IN IGNEOUS ROCKS

The mineral composition of igneous rocks contains mostly the elements oxygen and silicon, but many other elements form a variety of minerals in igneous rocks. There are three types of rocks, igneous, sedimentary and metamorphic. Igneous rocks form as a result of magma cooling and minerals within the magma crystallizing. There are a variety of minerals associated with igneous rocks and their abundance and crystal forms depend on the environment (pressure and temperature) under which the magma cooled. Igneous intrusive rocks crystallize very slowly as magma is pushed through the Earth's crust. Igneous extrusive rocks crystallize rapidly as magma is erupted through volcanic processes.

The Composition of Igneous Rocks:

Eight elements make up about 98 percent, by weight, of most magmas from which igneous rocks are made. These elements are:
• Oxygen (O)
• Silicon (Si)
• Aluminum (Al)
• Iron (Fe)
• Calcium (C)
• Sodium (Na)
• Potassium (K)
• Magnesium (Mg)
The composition of igneous rocks is mostly oxygen and silica. This is in agreement with the composition of the Earth's crust, which is also mostly oxygen and silica. Other elements that make up the remainder of igneous rock compositions include manganese (Mn) and Titanium (Ti).