Bismuth

Mineral Species: Post-Transition Metal

Chemical Formula: Bi

Mohs Scale Hardness: 2 - 2.5

Location: Worldwide.

Typical Appearance: In nature, usually silver-pink hue. Rarely in nature, but often acheived in lab conditions, high purity Bismuth can form stepped hopper crystals with rainbow colouring. 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 causing the rainbow colouring.