A method for chemical imaging of CaF2, CaF1, and Si by scanning tunneling spectroscopy is presented. This method is utilized for identifying the growth regimes of CaF2 and CaF1 on stepped Si(111)7X7. For CaF2 on Si(111), we find random islands, stripes, and ordered islands, depending on the supersaturation. For CaF2 on a CaF1 monolayer on Si(111), we find regular stripes that are continuous and separated from each other. CaF2 structures are attached to the bottom edge of a step when growing directly on Si, but they prefer the top of a step edge when growing on a CaF1 buffer layer. These highly regular, linear arrays of CaF2 stripes and dots can serve as masks for assembling more sophisticated nanostructures.