Cinnabar or cinnabarite sulfide, native vermilion), is the common ore of mercury.
Etymology The name comes from κινναβαρι, a
Greek word most likely applied by Theophrastus to several distinct substances.
Other sources say the word comes from the Persian شنگرف shangarf, a word of uncertain
origin.
In Latin it was sometimes known as minium, meaning also "red cinnamon", though both of
these terms now refer specifically to lead tetroxide.
Structure
HgS adopts two structures, i.e. it is dimorphous.
The more stable form is cinnabar, which has a structure akin to that for HgO: each Hg
center has two short Hg-S bonds, and four longer Hg---S contacts.
The black form of HgS has the zincblende structure.
Properties
Cinnabar is generally found in a massive, granular or earthy form and is bright scarlet
to brick-red in color.
It occasionally occurs in crystals with a non-metallic adamantine luster.
Cinnabar has a rhombohedral bravais lattice, and belongs to the hexagonal crystal system,
trigonal division.
Its crystals grow usually in a massive habit, though they are sometimes twinned.
The twinning in cinnabar is distinctive, and it forms a penetration twin that is ridged
with six ridges surrounding the point of a pyramid.
It could be thought of as two scalahedral crystals grown together, with one crystal
going the opposite way of the other crystal.
The hardness of cinnabar is 2–2.5, and its specific gravity 8.1.
Cinnabar resembles quartz in its symmetry and certain of its optical characteristics.
Like quartz, it exhibits birefringence.
It has the highest refractive power of any mineral.
Its mean index for sodium light is 3.08, whereas the index for diamond is 2.42 and that for
gallium(III) arsenide is 3.93.
Occurrence
Generally cinnabar occurs as a vein-filling mineral associated with recent volcanic activity
and alkaline hot springs.
Cinnabar is deposited by epithermal ascending aqueous solutions far removed from their igneous
source.
It is associated with native mercury, stibnite, realgar, pyrite, marcasite, opal, quartz,
chalcedony, dolomite, calcite and barite.
Cinnabar is found in all localities that yield mercury, notably Puerto Princesa; Almadén;
New Almaden; Hastings Mine and St. John's Mine, Vallejo, California; Idrija; New Idria;
Giza, Egypt; Landsberg, near Obermoschel in the Palatinate; Ripa, at the foot of the Apuan
Alps and in the Mount Amiata; the mountain Avala; Huancavelica; Murfreesboro, Arkansas;
Terlingua; and the province of Guizhou in China, where fine crystals have been obtained.
It was also mined near Red Devil, Alaska on the middle Kuskokwim River.
Red Devil was named after the Red Devil cinnabar mine, a primary source of mercury.
Cinnabar is still being deposited at the present day from the hot waters of Sulphur Bank Mine
in California and Steamboat Springs, Nevada.
Mining and extraction of mercury
Cinnabar has been mined since the Neolithic Age.
During the Roman Empire it was mined both as a pigment and for its mercury content,
and it has been the main source of mercury throughout the centuries.
To produce liquid mercury, crushed cinnabar ore is roasted in rotary furnaces.
Pure mercury separates from sulfur in this process and easily evaporates.
A condensing column is used to collect the liquid metal, which is most often shipped
in iron flasks.
Toxicity
Because of its mercury content, cinnabar can be toxic to human beings.
Though peoples in ancient South America often used cinnabar for art, or processed it into
refined mercury "the toxic properties of mercury were well known.
It was dangerous to those who mined and processed cinnabar, it caused shaking, loss of sense,
and death.
Data suggests that mercury was retorted from cinnabar and the workers were exposed to the
toxic mercury fumes."
Overexposure to mercury, mercurialism, was seen as an occupational disease to the ancient
Romans, "Mining in the Spanish cinnabar mines of Almadén, 225 km southwest of Madrid, was
regarded as being akin to a death sentence due to the shortened life expectancy of the
miners, who were slaves or convicts."
Decorative use Cinnabar has been used for its color in the
New World since the Olmec culture.
Cinnabar was used in royal burial chambers during the peak of Maya civilization, most
dramatically in the Tomb of the Red Queen in Palenque, where the remains of a noble
woman and objects belonging to her in her sarcophagus were completely covered with bright
red powder made from cinnabar.
The most popularly known use of cinnabar is in Chinese carved lacquerware, a technique
that apparently originated in the Song Dynasty.
The danger of mercury poisoning may be reduced in ancient lacquerware by entraining the powdered
pigment in lacquer, but could still pose an environmental hazard if the pieces were accidentally
destroyed.
In the modern jewelry industry, the toxic pigment is replaced by a resin-based polymer
that approximates the appearance of pigmented lacquer.
Other forms Hepatic cinnabar is an impure variety from
the mines of Idrija in the Carniola region of Slovenia, in which the cinnabar is mixed
with bituminous and earthy matter.
Metacinnabarite is a black-colored form of HgS, which crystallizes in the cubic form.
Synthetic cinnabar is produced by treatment of Hg(II) salts with hydrogen sulfide to precipitate
black, synthetic metacinnabarite, which is then heated in water.
This conversion is promoted by the presence of sodium sulfide.
Hypercinnabar, crystallised in the hexagonal form.
See also
China red Classification of minerals
List of minerals References
External links MSDS for cinnabar
Dartmouth Toxic Metals Research Program – Mercury Cinnabar visual reference