The Periodic Spiral assigns the color crimson (a medium red) to titanium, iron, zinc, selenium, rutherfordium, hassium, ununbium, and (the recently discovered and provisionally named, but subsequently disclaimed) ununhexium, element 118. The blood red color (in the powdered form) of hematite, an important ore of iron, lends itself well in use as a pigment. Synthetic red Iron oxide pigments are available in a range of hues from reddish orange through dull red and burgundy. Iron produces the red color of limonite, (hydrated iron oxide hydroxide), as well as the red color of blood. Bright red zincite, or red oxide of zinc, is a mineral well known to collectors. Amorphous selenium is red in powdered form; crystalline monoclinic selenium is deep red. The vibrant red coloring of Selenium Red Glass, developed in the 1890's by Nicolas Kopp, met the US railroad industry's standards for signaling lights. In the diet, selenium helps preserve the integrity of red blood cells.