High Quality Content by WIKIPEDIA articles! Paris Green is an inorganic compound more precisely known as copper(II) acetoarsenite. It is a highly toxic emerald-green crystalline powder that has been used as a rodenticide and insecticide, and also as a pigment, despite its toxicity. It is also used as a blue colorant for fireworks. The color of Paris Green is said to range from a pale, but vivid, blue green when very finely ground, to a deeper true green when coarsely ground.