Vermilion is a dense, opaque pigment with a clear, brilliant hue.[9] The pigment was originally

made by grinding a powder of cinnabar, the ore which contains mercury. The chemical

formula of the pigment is HgS (mercury(II) sulfide); like most mercury compounds it is toxic.

Vermilion is not one specific hue; Mercuric sulfides make a range of warm hues – from bright

orange-red to a duller bluish-red. Differences in hue are caused by the size of the ground

particles of pigment. Larger crystals produce duller and less-orange hue.

Cinnabar pigment was a side-product of the mining of mercury, and mining cinnabar was

difficult, expensive and dangerous, because of the toxicity of mercury. The Greek

philosopher Theophrastus of Eresus (371-286 BC) described the process in "De Lapidibus",

the first scientific book on minerals. Efforts began early to find a better way to make the

pigment.

The Chinese were probably the first to make a synthetic vermilion as early as the 4th century

BC. The Greek alchemist Zosimus of Panopolis (Third–Fourth century AD) wrote that such a

method existed. In the early ninth century the process was accurately described by the Arab

or Persian alchemist Jabir ibn Hayyan (722–804) in his book of recipes of colors, and the

process began to be widely used in Europe.[9][10]

The process described by Jabir ibn Hayyan was fairly simple. Mercury and sulfur were mixed

together, forming a black compound of sulphide of mercury, called Aethiopes mineralis. This

was then heated in a flask. The compound vaporized, and recondensed in the top of the

flask. The flask was broken, the vermilion was taken out, and it was ground. When first

created the pigment was almost black, but as it was ground the red color appeared. The

longer the color was ground, the finer the color became. The Italian Renaissance

artist Cennino Cennini wrote: "Know that if you ground it every day for twenty years the color

would become finer and more handsome."[11]

During the 17th century a new method of making the pigment was introduced, known as the

'Dutch' method. Mercury and melted sulfur were mashed to make black mercury sulfide, then

heated in retort, producing vapors condensing as a bright, red mercury sulfide. To remove

the sulfur these crystals were treated with a strong alkali, washed and finally ground under

water to yield the commercial powder form of pigment.[12] The pigment is still made today by

essentially the same process.