Kauai Sea Salt

The colors in this image are the result of diffraction caused by small cavities in these thin crystals. These crystals were prepared by drawing a saturated salt solution over the slide and then allowing the water to slowly evaporate. The red clay (Alaea) seems to disturb regular crystal growth and results in crystals with a very high surface area relative to the projected area of the crystal. These small cavities in the crystals results in the diffraction colors in this image.