Realgar Meanings, Zodiacs, Planets, Elements, Colors, Chakras, and more. Science & Origin of RealgarRealgar, also known as Ruby Sulphur or Ruby of Arsenic, is a toxic arsenic sulfide mineral that crystallizes in the form of grains, tabular crystals, and masses. The color can range from a bright red, to a soft yellow. Over time, when exposed to light, Realgar …