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Bowen's Reaction Series

N. L. Bowen, experimenting on the order in which minerals crystallized from a melt, determined a reaction series for minerals:

discontinuous -------- continuous -------most refractory / least stable at surface
---olivine -------------Ca-rich feldspars------------------mafic
-----pyroxenes -.-------/
---------\------------ plagioclase
-------amphiboles -.--/
------------\------ Na-rich feldspars ------------------intermediate
-- ------------quartz---------------------------------------felsic
--------------------------------------------most fusible / most stable at surface

The feldspars crystallize in a continuous series with the calcium rich endmembers cystallizing out of a melt earliest, the sodium rich members crystallizing later, and the orthoclase feldspar endmember cystallizing last. In the discontinuous branch, the nesosilicate olivine constructed of simple [SiO4]4- tetrahedra crystallizes first, followed in sequence by single-chain pyroxenes, amphiboles, sheet micas, and 3D-framework quartz.

Minerals, such as refractory olivine, which crystallize out of melts at depth are least stable and most prone to weathering, at Earth's surface. Conversely, highly fusible quartz is very stable at the surface.

See magmatic differentiation.


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