Neutron radiography can provide images of the internal structure of rocks, through virtue of the differing neutron attenuation characteristics of hydrogen versus other elements commonly found in nature. Thus, pores filled with water, or oil, will attenuate neutrons to a greater extent than the surrounding rock matrix. Similarly, the internal structure of iron ore, which contains mixtures of limonite and goethite, which contain hydrogen in their crystalline lattice, and magnetite (no hydrogen), can also be imaged using neutrons. The ability of the technique to distinguish "effective porosity" versus "total porosity" is derived from the neutron radiographs. Images of two iron ore samples have also been analyzed to demonstrate how both different mineral assemblages and porosity can be determined.