Bismuth Crystal Photomicrography

A close-up 10:1 Photomicrography image of a Bismuth Crystal.

Bismuth is a chemical element that has the symbol Bi. Bismuth is the most naturally diamagnetic of all metals, and only mercury has a lower thermal conductivity. The spiral stair stepped structure of a bismuth crystal is the result of a higher growth rate around the outside edges than on the inside edges. The variations in the thickness of the oxide layer that forms on the surface of the crystal causes different wavelengths of light to interfere upon reflection, thus displaying a rainbow of colors.