Realgar - an arsenic sulphide mineral. Historically used as rat poison, red paint pigment, medicine, fabric dye, and to make white fireworks. Poisonous and carcinogenic. Burns with a bluish flame.

Victorians used Scheele’s Green—a.k.a. copper arsenite—to color everything from textiles to sweets to wallpaper. Some believe that Napoleon’s death was a result of green-papered rooms in the house where he was exiled. In the 1930s, Scheele’s Green was used as an insecticide.

Orpiment - an arsenic sulfide mineral, historically used to kill flies and tip poison arrows. Its striking yellow hue captivated alchemists who sought to create gold, and it adorns the pages of many Medieval manuscripts, including the Book of Kells. Orpiment is still used in the tanning industry to strip hair from animal hides.