Paris green

Paris green (copper(II) acetate triarsenite or copper(II) acetoarsenite) is an arsenic- and copper-containing pigment. It is an emerald-green crystalline powder that is also known as Mitis green, Schweinfurt green, Sattler green, emerald green, Vienna green, emperor green or mountain green. It is highly toxic and has thus also been used as a rodenticide and insecticide. Its formula is Cu(C2H3O2)2·3Cu(AsO2)2. It was manufactured in 1814 to be a pigment to make a vibrant green paint, and was used by many notable painters in the 19th century. The color of Paris green is said to range from a pale blue-green when very finely ground, to a deeper green when coarsely ground. Due to the presence of arsenic, the pigment is extremely toxic. In paintings, the color can degrade quickly.