A quantitative technique was developed to aid the determination of the spatial distribution of magnetite to the constituent minerals in an igneous rock. The results show the magnetite to be preferentially associated with the ferromagnesian silicates; they further lend support that the magnetite was formed by precipitation, oxidation reaction, and alteration. The amount of magnetite formed by each process can be estimated and was found to be in decreasing order, as listed above. The technique allows intergranular relations to be noted and quantified. This permits a more justified speculation as to the crystallization history of an igneous pluton.