Efforts to map electrostatic properties, derived from accurate X-ray diffraction data, in crystals are underway. The total electrostatic potential in hydrogen-bonded molecular-crystals provides a nice picture of chemical functions around the periphery of a molecule. From these potentials, electrostatic intermolecular energies are determined. The mapping of electrical fields in minerals such as quartz, corrundum and fosterite provide insight as to sites for cation preferences. Although difficult to determine accurately, electronic field gradients are also established at several mean nuclear sites.