Mercury sulfide

Mercury sulfide
IUPAC name Mercury sulfide
Other names Cinnabar Vermillion
Identifiers
CAS number	1344-48-5 Y
Properties
Molecular formula	HgS
Molar mass	232.66 g/mol
Density	8.10 g/cm3
Melting point	580 °C decomp.
Solubility in water	insoluble
Band gap	2.1 eV (direct, α-HgS) [1]
Refractive index (nD)	w=2.905, e=3.256, bire=0.3510 (α-HgS) [2]
Hazards
MSDS	ICSC 0981
EU Index	080-002-00-6
EU classification	Very toxic (T+) Dangerous for the environment (N)
R-phrases	R26/27/28, R33, R50/53
S-phrases	(S1/2), S13, S28, S45, S60, S61
Flash point	Non-flammable
Related compounds
Other anions	Mercury oxide Mercury selenide Mercury telluride
Other cations	Zinc sulfide Cadmium sulfide
Y sulfide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Mercury sulfide, mercuric sulfide, or mercury(II) sulfide is a chemical compound composed of the chemical elements mercury and sulfur. It is represented by the chemical formula HgS. It is virtually insoluble in water.^[3]

Crystal structure

Cinnabar from Nevada, USA

HgS is dimorphic with two crystal forms:

• red cinnabar (α-HgS, hexagonal, hP6, P3221), is the form in which mercury is most commonly found in nature.
• black, metacinnabar (β-HgS), is less common in nature and adopts the zinc blende (T²_d-F-43m) crystal structure.

Crystals of red, α-HgS, are optically active. This is caused by the Hg-S helices in the structure.^[4]

Preparation and chemistry

β-HgS is precipitated as a black powder when H₂S is bubbled through solutions of Hg(II) salts.^[5] β-HgS is unreactive to all but concentrated acids.^[3]
Mercury metal is produced from the cinnabar ore by roasting in air and condensing the vapour.^[3]

Uses

α-HgS is used as a red pigment when it is known as vermilion. Vermilion is known to darken and this has been ascribed to conversion from red α-HgS to black β-HgS. Investigations at Pompeii where red walls when originally excavated have darkened has been ascribed to the formation of Hg-Cl compounds (e.g., corderoite, calomel, and terlinguaite) and calcium sulfate, gypsum, rather than β-HgS, which was not detected.^[6]

See also

• Cinnabar
• Mercury poisoning

References

1. ^ L. I. Berger, Semiconductor Materials (1997) CRC Press ISBN 0849389127
2. ^ Webminerals
3. ^ ^{a b c} Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 1406. ISBN 0-08-022057-6. 
4. ^ Glazer, A. M.; Stadnicka K. (1986). "On the origin of optical activity in crystal structures". J. Appl. Cryst. 19 (2): 108–122. doi:10.1107/S0021889886089823. 
5. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5 
6. ^ Cotte, M; Susini J, Metrich N, Moscato A, Gratziu C, Bertagnini A, Pagano M (2006). "Blackening of Pompeian Cinnabar Paintings: X-ray Microspectroscopy Analysis". Anal. Chem. 78 (21): 7484–7492. doi:10.1021/ac0612224. PMID 17073416. 

External links

• National Pollutant Inventory - Mercury and compounds Fact Sheet