Lab 3: Trace element partitioning during crystallization#
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Archived course materials from Spring 2026.
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Introduction#
In this lab, you will compare Ni concentrations in olivines to modeled predictions of Ni concentrations during batch and fractional crystallization. You will find the partition coefficients, \(D\), that best fit each crystallization model, and you will compare those results to experimentally determined partitioning for Ni to argue for which crystallization model more accurately describes the magmatic system that these olivine samples formed in. Recall:
The partition coefficient, \(D\), describes the ratio of concentrations for an element between a mineral and a melt at equilibrium:
Batch crystallization describes a scenario where some fraction of a magmatic system crystallizes and remains in equilbrium with the liquid.
Fractional crystallization describes the continuous removal of mineral percipitates from a melt:
C is the concentration of a trace element. Subscript L represents the melt phase. Subscript S represents the solid phase. C\(_0\) means at the initial conditions when melt is 100% of the system. D is the partition coefficient, and F is the melt fraction (where 1 is 100% melt).