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Magma is the word used to describe melted or molten rock inside Earth. Magma is composed of elements, minerals, and gases that were present in the rock before it melted.

The major elements in magma are those present in Earth's crust: oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K). These elements combine to form minerals such as magnetite, hauynite, olivine, pyroxene, hornblende, plagioclase, potassium feldspar (k-feldspar), and quartz.

Magma also contains dissolved gases like water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2).

More on the three types of magma