Mercury sulfide, or mercury(II) sulfide is a chemical compound composed of the

chemical elements A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler su ...

mercury and

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

. It is represented by the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

HgS. It is virtually insoluble in water.

Crystal structure

HgS-alpha-cinnabar-xtal-1999-looking-down-a-axis-CM-3D-balls

HgS-alpha-cinnabar-xtal-1999-looking-down-c-axis-CM-3D-balls

HgS is dimorphic with two crystal forms: * red

cinnabar Cinnabar (), or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the bri ...

(α-HgS,

trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...

, hP6, P3221) is the form in which mercury is most commonly found in nature. Cinnabar has rhombohedral crystal system. Crystals of red are

optically active Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...

. This is caused by the Hg-S helices in the structure. * black metacinnabar (β-HgS) is less common in nature and adopts the zinc blende (''T''²_d-''F'3m'')

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pattern ...

Preparation and chemistry

β-HgS precipitates as a black solid when Hg(II) salts are treated with H₂S. The reaction is conveniently conducted with an acetic acid solution of

mercuric acetate Mercury(II) acetate is the chemical compound with the formula Hg( O2 CC H3)2. Commonly abbreviated Hg(OAc)2, this compound is employed as a reagent to generate organomercury compounds from unsaturated organic precursors. It is a white water-sol ...

. With gentle heating of the slurry, the black polymorph converts to the red form. β-HgS is unreactive to all but concentrated acids. Mercury is produced from the

ore by roasting in air and condensing the vapour. :HgS → Hg + S

Uses

When α-HgS is used as a red pigment, it is known as

vermilion Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its corresponding color. It i ...

. The tendency of vermilion to darken has been ascribed to conversion from red α-HgS to black β-HgS. However β-HgS was not detected at excavations in Pompeii, where originally red walls darkened, and was attributed to the formation of Hg-Cl compounds (e.g.,

corderoite Corderoite is an extremely rare mercury sulfide chloride mineral with formula Hg3S2Cl2. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yello ...

calomel Calomel is a mercury chloride mineral with formula Hg2Cl2 (see mercury(I) chloride). The name derives from Greek ''kalos'' (beautiful) and ''melas'' (black) because it turns black on reaction with ammonia. This was known to alchemists. Calomel ...

, and

terlinguaite Terlinguaite is the naturally occurring mineral with formula Hg2 Cl O. It is formed by the weathering of other mercury-containing minerals. It was discovered in 1900 in the Terlingua District of Brewster County Brewster County is a county l ...

) and

calcium sulfate Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris ...

, gypsum. As the mercury cell as used in the chlor-alkali industry (

Castner–Kellner process The Castner–Kellner process is a method of electrolysis on an aqueous alkali chloride solution (usually sodium chloride solution) to produce the corresponding alkali hydroxide, invented by American Hamilton Castner and Austrian Carl Kellner in ...

) is being phased out over concerns over mercury emissions, the metallic mercury from these setups is converted into mercury sulfide for underground storage. With the band gap of 2.1eV and its stability, it is possible to be used as photo-electrochemical cells

References

{{DEFAULTSORT:Mercury Sulfide Sulfides Mercury(II) compounds Zincblende crystal structure

Crystal structure

Preparation and chemistry

Uses

See also

References