Nickel Selenide, NiSe

Nickel Monoselenide or Nickel Selenide, NiSe, results in regular double tetrahedra when nickel is exposed at dull red heat to vaporised selenium diluted with nitrogen. It is also obtained by the action of hydrogen selenide upon anhydrous nickel chloride at bright red heat. It is greyish blue in colour. Density 8.46.