This is salt, marine salt. Over the metal of study, the salt was dissolved in water; a process carried out in-situ under the monitoring of an environmental scanning electron microscope (ESEM). This was done with the purpose of studying marine corrosion of metals, exploiting the possibilities of our nice ESEM at CIC nanoGUNE. After each experiment, conducted close to the water triple point, returning back to dry conditions lead to the crystallization of NaCl in the way shown in the image. The crystallization occurred from right to left in the image, with hills collecting the salt of a few micros around. The hills demonstrate similar slopes everywhere, suggesting the same NaCl crystal orientation of every nuclei, probably imposed by the metal substrate. Tilting the stage to almost 90° (thanks to our nice ESEM setup) I could make this image a bit similar to a sand desert.
Image taken by Bentejui Medina Clavijo.