fractional crystallization

geology

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June 26, 2026

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Fractional crystallization is a geological process where minerals crystallize from a magma at different temperatures. As a magma cools, early-formed minerals, which are typically denser, settle out. This removal of early crystals leaves the remaining liquid magma with a different chemical composition, leading to the formation of new minerals as cooling continues.1

This process is fundamental to understanding how different types of igneous rocks form from a single parent magma. For example, a basaltic magma can transform into rocks like granite through fractional crystallization, as early-formed minerals are separated from the melt. This process, along with assimilation, where magma incorporates surrounding rock, can explain the diversity of magmatic compositions observed in nature.12

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igneous rock
Bowen’s reaction series
…in the series is by fractional crystallization. In this process, the early-formed minerals are removed from the liquid by gravity (such minerals as olivine and pyroxene are denser than the liquid from which they crystallized), and so unreacted liquid remains later in the series.
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…in the series is by fractional crystallization. In this process, the early-formed minerals are removed from the liquid by gravity (such minerals as olivine and pyroxene are denser than the liquid from which they crystallized), and so unreacted liquid remains later in the series.
Read More

volcano
Subduction volcanoes
This process is called fractional crystallization. Also, basaltic magmas have enough excess heat to partially melt the continental host rocks through which they are ascending. Because continental rocks are generally higher in silica, potassium, and sodium than are oceanic rocks, this process of assimilation and mixing can also play…
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This process is called fractional crystallization. Also, basaltic magmas have enough excess heat to partially melt the continental host rocks through which they are ascending. Because continental rocks are generally higher in silica, potassium, and sodium than are oceanic rocks, this process of assimilation and mixing can also play…
Read More