Vermilion is an opaque red pigment prepared from the mineral cinnabar, as well as the name of the resulting color. The pigment has been in use around the world for many thousands of years. The first recorded use of vermilion as a color name in English was in 1289. The first recorded use of cinnabar as a color name (the color name "cinnabar" is a synonym for vermilion) in English was in 1382. Most naturally produced vermilion comes from cinnabar mined in China, and vermilion is nowadays commonly called 'China red'. The name 'vermilion' is derived from the French vermeil (indicating any red dye), from Latin vermiculum, the ancient insect dye from Kermes vermilio. Words for red hues in Portuguese (vermelho) and Catalan (vermell) arose similarly. 'Cinnabar' and 'vermilion' were used interchangeably to describe either the natural or manufactured pigment until the 17th century when vermilion became the more common name. By the late 18th century 'cinnabar' applied to the unground natural mineral only.
The chemical structure of the pigment is HgS mercuric sulfide; like most mercury compounds it is toxic. Vermilion is now produced by reacting mercury with molten sulfur. Mercuric sulfides offer a range of warm hues – from bright orange-red to a duller bluish-red. Differences in hue arise via the size of the ground particles of pigment. Larger crystals produce duller and less-orange hue. It is now theorized that coarser, duller "Chinese" forms of vermilion will prove to be more permanent than the more orange "French" variety. It is also theorized that purification of any such pigment benefits its general stability. For safety reasons the use of vermilion has recently been replaced (in some applications) with cadmium red, yielding a similar range of hues, although cadmium carries severe hazards of its own.