The bulk distribution coefficient is used to calculate the elemental composition for any element that makes up a mineral in a rock. The bulk distribution coefficient, , is defined as
where  is the element of interest in the mineral, and  is the weight fraction of mineral  in the rock.  is the distribution coefficient for the element in mineral . This constant can be used to describe how individual elements in a mineral is concentrated in two different phases. During chemical fractionation, certain elements may become more or less concentrated, which can allow geochemists to quantify the different stages of magma differentiation. Ultimately, these measurements can be used to provide further understanding of elemental behavior in different geologic settings.