Cinnabar and Vermilion: Beautiful and Toxic Mineral and Pigment
An Attractive and Useful Mineral
Cinnabar is a beautiful orange red to dark red mineral that is prized for both its color and its mercury content. In ancient times, cinnabar was ground into a powder to form a pigment called vermilion. This pigment was used for art and decoration and was also added to cosmetics. It's still used in artists’ paints today, although it's often replaced by synthetic and less toxic pigments.
Cinnabar is made of a compound called mercury (ll) sulfide or mercuric sulfide. The chemical formula of this compound is HgS. Mercury (ll) sulfide occurs in two forms in nature—the more common red or cinnabar form and the rarer black or metacinnabar form. Mercury and mercury compounds are toxic to humans, although cinnabar is not as poisonous as some other forms of mercury.
Cinnabar is usually found in rocks that form near volcanic activity or in hot springs. It’s produced near the Earth’s surface from hot liquids that bubble up from deeper in the Earth. Most of the world’s mercury supply is obtained from cinnabar. Major cinnabar producers today include Spain, China, Italy, Serbia, Slovenia, and parts of the United States.
Uses of Cinnabar in the Past
Cinnabar, vermilion, mercury (ll) sulfide, and mercuric sulfide all refer to the same substance (with the exception of the rare black form of mercury (ll) or mercuric sulfide). Like several other red materials in nature, cinnabar was also known by the evocative name of “dragon’s blood” in earlier times. Its vibrant red color was a great attraction for people looking for pigments.
Ancient Romans created paintings and decorated statues and their faces with ground cinnabar mixed with a medium such as egg yolk or plant gums. The Mayan people used cinnabar to decorate burial chambers, the sarcophagi, and the dead bodies of important members of their society.
Earlier women in India wore vermilion along the parting of their hair and in a dot on their foreheads to indicate that they were married. Some modern Indian women still follow this custom. Today the pigment, which is known as sindoor, is made of turmeric, lime juice, and other substances instead of cinnabar.
Ancient Chinese people used cinnabar in their famous red lacquers and in special inks. The technique for making artificial vermilion from mercury and sulfur was apparently first devised in China in the eighth century. Vermilion from China is sometimes known as China Red.
A Large Specimen of Cinnabar
Art and Vermilion in the Villa of the Mysteries in Pompeii
Vermilion was loved by artists of the past. Paintings with vibrant red colors created by vermilion have survived, including some in an Ancient Roman villa shown in the video below. The villa paintings may not have been as richly colored in the past as they are today, however. They've been preserved with a wax layer, which darkened the paint when it was applied. The paintings are gradually being restored to their natural color as well as being protected by new methods.
The name of the villa which has left us such interesting art is the Villa of (the) Mysteries. It stands just outside the city of Pompeii. The villa was affected by the famous eruption of Mount Vesuvius in 79 A.D., but not to the same extent as many other buildings in the area.
The Villa of the Mysteries is believed to have been used for initiation into a mystery cult of Dionysus, the god of wine. The murals on the walls appear to depict initiates and their experiences, although expects are not quite certain about the meaning of all of the paintings. The murals are frescoes, which are paintings created on wet plaster that become an integral part of a wall. According to the Italian Ministry of Cultural Heritage and Activities, some of the scenes in the frescoes show the drinking of wine and ecstatic dancing, which were rituals of the mystery cult.
Frescoes in the Villa of Mysteries
Color Change in Vermilion
Unfortunately, in some cases vermillion used in historical art has turned brown, black, or grey over time. The color loss of vermilion is of great concern to art historians and to those working in art conservation.
Researchers have discovered a chemical reaction which may be responsible for vermilion's loss of color. They say that chlorine salts in the air may act as a catalyst for a reaction that releases mercury from the pigment when it's exposed to light. The thin layer of tiny mercury particles on top of the vermilion may give the mineral a dark appearance. The grey color over some vermilion may be due to the production of mercury (l) chloride, which is white in color. Some researchers think that the change in appearance of vermilion is a more complex process than this, however.
Once the cause or causes of vermilion's color change have been discovered, it may be possible to protect historical art from further damage. If a way to reverse the damage is discovered, it may even be possible to return the art to its former glory.
Uses of Cinnabar Today
In more recent times, powdered cinnabar or vermillion was added to candies as a food coloring, although it's no longer used for this purpose. Cinnabar is still part of many traditional Chinese medicines, however.
Cinnabar in the form of natural or artificially made vermillion is sold today as an artist’s paint. The paint is accompanied by a warning to avoid ingestion and skin contact. Many artists use cadmium red as a replacement for vermillion because it's safer and more permanent.
Some rock and mineral collectors like to include cinnabar samples in their collection. The color of the mineral varies considerably and ranges from orange to a deep purple-red. Some people enjoy the hunt for the perfect specimen.
The main use of cinnabar today is for mercury production. To extract mercury from cinnabar, the mineral is heated. The mercury escapes from the mineral as a gas, which is then cooled and condensed to make liquid mercury. Mercury is the only metal that is liquid at room temperature. It needs to be treated with great caution because it can be absorbed through the skin and releases dangerous vapors.
The early alchemists called mercury “quicksilver” for two reasons. One is that mercury is silver in color. The other is that when it’s placed on a surface it forms beads that roll around as though they are alive.
Other Meanings of the Word Cinnabar
The word "cinnabar" is sometimes used to name items unrelated to the cinnabar mineral in order to convey an exotic impression. For example, Cinnabar perfume contains no mercury. Today's cinnabar boxes are generally made of wood that is covered by a red lacquer containing no cinnabar or by a red resin polymer. The lacquer or resin is imprinted with a design. Cinnabar jewelry doesn't contain the cinnabar mineral, since mercury compounds shouldn't stay in contact with the skin.
Mercury exists in three forms—elemental mercury (pure metallic mercury), organic mercury (mainly methylmercury, the form found in some fish) and inorganic mercury, such as the mercury (ll) sulfide that makes up cinnabar. Unlike organic mercury, inorganic mercury doesn't contain carbon.
The severity of mercury poisoning in humans depends on many factors, including the form of the mercury, the way in which the mercury is absorbed into the body (through ingestion, inhalation, or skin absorption), the dose of mercury absorbed, the duration of the exposure, the frequency of the exposure, and the age and health of the affected person. Mercury poisoning can result in damage to the nervous and muscular systems as well as damage to the gastrointestinal tract, kidneys, and respiratory system.
Inorganic Mercury Toxicity
Inorganic mercury such as the mercury found in cinnabar is the least toxic form of mercury, but it's still poisonous.
- Inorganic mercury is absorbed through the lining of the digestive tract, but in lower quantities than organic mercury.
- Inorganic mercury doesn’t vaporize much at room temperature, so inhalation is not a major problem. The dust is dangerous for the lungs, however.
- Small amounts of inorganic mercury compounds can be absorbed through the skin.
- Contact with high levels of inorganic mercury can cause skin rashes.
- Although it’s less likely to cause nervous system damage than other forms of mercury, chronic exposure to inorganic mercury can damage the kidneys and the nervous system.
Mercury: Properties and Safety
Toxicity and Safe Use of Cinnabar
There is uncertainty about how poisonous cinnabar is and about the amount required to produce dangerous effects. Scientists generally recommend that we limit our exposure to all mercury compounds, however, including inorganic mercury.
People using cinnabar are warned not to inhale cinnabar dust and to be very careful when breaking the mineral in case dust is created. The mineral mustn’t be ingested or licked. In addition, it mustn’t be heated, which might trigger mercury vapor release. Opinions are divided about whether cinnabar is safe to touch. Mercury (ll) sulfide can be absorbed through the skin, but how much is actually absorbed from a lump of cinnabar mineral is unknown. Since there are unanswered questions about the mineral's safety, it's best to wear gloves when handling it.
One potentially serious problem is that sometimes drops of liquid mercury can be found in a piece of cinnabar mineral, which are more dangerous than the cinnabar itself. Liquid mercury releases a poisonous vapor.
A Beautiful Mineral
Cinnabar is a beautiful but potentially dangerous mineral. Anyone coming into close contact with the mineral—especially if this happens on a frequent basis—should be aware of important safety precautions. It's wonderful to be able to admire the mineral at close range, as long as this is done safely.
- Mindat.org (an online mineralogical database) has an information page about cinnabar.
- The Pigments Through the Ages site from webexhibits.org includes facts about vermilion.
- The CDC (Centers for Disease Control and Prevention) has a useful webpage about mercury facts in relation to health.
- The website of the Italian Ministry of Cultural Heritage and Activities gives information about the Villa of the Mysteries in Pompeii.
- Mercury's ability to darken art is discussed by the Royal Society of Chemistry.
- Darkening of vermilion over time is described by the APS (American Physics Society).
© 2011 Linda Crampton