Elbaite tourmaline

Tourmaline is a semi-precious cyclosilicate mineral; elbaite is a lithium-rich species of this group. These minerals come in a variety of colors ranging from black, to violet, green, pink, and red. Occasionally these colors will combine, as seen in the polished watermelon tourmaline in the middle two images. 

  • Rubellite tourmaline crystals on matrix, Brazil
  • Polished slices of watermelon tourmaline, Brazil (middle images)
  • Faceted rubellite tourmaline, Madagascar

From the Grainger Hall of Gems at The Field Museum.