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Cinnabar

 

Cinnabar

Cinnabar
Cinnabar
General
Category Sulfide mineral
Formula
(repeating unit)
mercury(II) sulfide, HgS
Strunz classification 02.CD.15a
Crystal symmetry Trigonal Trapezohedral
H-M symbol: 3 2
Space group: P31 2 1
Unit cell a = 4.145(2) Å, c = 9.496(2) Å, Z=3
Identification
Color Cochineal-red, towards brownish red and lead-gray
Crystal habit Rhombohedral to tabular; granular to massive and as incrustations
Crystal system Trigonal
Twinning Simple contact twins, twin plane {0001}
Cleavage Prismatic {1010}, perfect
Fracture Uneven to subconchoidal
Tenacity Slightly sectile
Mohs scale hardness 2-2.5
Luster Adamantine to dull
Streak Scarlet
Diaphaneity Transparent in thin pieces
Specific gravity 8.176
Optical properties Uniaxial (+)
Refractive index nω = 2.905 nε = 3.256
Birefringence δ = 0.351
Solubility 1.04 x 10-25 g per 100 ml water (Ksp at 25°C = 2 x 10-32)[1]
References [2][3][4]

Cinnabar (pronounced ) or cinnabarite (red mercury(II) sulfide (HgS), native vermilion), is the common ore of mercury.

Contents

  • Etymology 1
  • Structure 2
  • Properties 3
  • Occurrence 4
  • Mining and extraction of mercury 5
  • Toxicity 6
  • Decorative use 7
  • Other forms 8
  • See also 9
  • References 10
  • External links 11

Etymology

The name comes from κινναβαρι (kinnabari),[5] a Greek word most likely applied by Theophrastus to several distinct substances. Other sources say the word comes from the Persian شنگرف shangarf (Arabicized as زنجفرة zinjifrah), a word of uncertain origin (also compare, Sanskrit सुगर sugara). In Latin it was sometimes known as minium, meaning also "red cinnamon", though both of these terms now refer specifically to lead tetroxide.[6]

Structure

Crystal structure of cinnabar

HgS adopts two structures, i.e. it is dimorphous.[7] The more stable form is cinnabar, which has a structure akin to that for HgO: each Hg center has two short Hg-S bonds (2.36 Å), and four longer Hg---S contacts (3.10, 3.10, 3.30, 3.30 Å). The black form of HgS has the zincblende structure.

Properties

Cinnabar

Cinnabar is generally found in a massive, granular or earthy form and is bright scarlet to brick-red in color.[8] 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,[9] whereas the index for diamond is 2.42 and that for gallium(III) arsenide (GaAs) is 3.93.

Occurrence

Cinnabar mercury ore from Nevada, USA

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 (those near surface and not too hot) far removed from their igneous source.

It is associated with native mercury, stibnite, realgar, pyrite, marcasite, opal, quartz, chalcedony, dolomite, calcite and barite.[2]

Cinnabar is found in all localities that yield mercury, notably Puerto Princesa (Philippines); Almadén (Spain); New Almaden (California); Hastings Mine and St. John's Mine, Vallejo, California;[10] Idrija (Slovenia); New Idria (California); Giza, Egypt; Landsberg, near Obermoschel in the Palatinate; Ripa, at the foot of the Apuan Alps and in the Mount Amiata (Tuscany); the mountain Avala (Serbia); Huancavelica (Peru); Murfreesboro, Arkansas; Terlingua (Texas); 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

Apparatus for the distillation of cinnabar, Alchimia, 1570

As the most common source of mercury in nature,[11] cinnabar has been mined for centuries, even as far back as the Neolithic Age.[12] During the Roman Empire it was mined both as a pigment (Vitruvius, DA VII; IV-V) (Pliny, HN; XXXIII, XXXVI-XLII) and for its mercury content (Pliny HN; XXXIII, XLI).

To produce liquid mercury (quicksilver), 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 (as a means to gild silver and gold to objects) "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."[13] 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."[14]

Decorative use

Cinnabar has been used for its color in the New World since the Olmec culture.[15] Cinnabar was used in royal burial chambers during the peak of Maya civilization, most dramatically in the Tomb of the Red Queen in Palenque (600–700 AD), 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.[16]

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,[17] 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.[18]
  • Hypercinnabar, crystallised in the hexagonal form.

See also

References

  1. ^ Meyers, J. (1986). Chem. Ed. 63. p. 689. 
  2. ^ a b Mineral Handbook
  3. ^ Mindat
  4. ^ Webmineral
  5. ^ "Cinnabar". Online Etymology Dictionary. Retrieved 22 May 2012. 
  6. ^ Daniel V. Thompson, The Materials and Techniques of Medieval Painting, (1956), Dover Publications, p. 100-102
  7. ^ Wells, A. F. (1984). Structural Inorganic Chemistry. Oxford: Clarendon Press.  
  8. ^ King, R. J. (2002). "Minerals Explained 37: Cinnabar". Geology Today 18 (5): 195–199.  
  9. ^ Schumann, W. (1997). Gemstones of the World. New York: Sterling.  
  10. ^ C.Michael Hogan, Marc Papineau et al., Environmental Assessment of the columbus Parkway Widening between Ascot Parkway and the Northgate Development, Vallejo, Earth Metrics Inc. Report 7853, California State Clearinghouse, Sept, 1989
  11. ^ http://ec.gc.ca/mercure-mercury/default.asp?lang=En&n=2C1BBBDA-1
  12. ^ Martín-Gil, J.; Martín-Gil, F. J.; Delibes-de-Castro, G.; Zapatero-Magdaleno, P.; Sarabia-Herrero, F. J. (1995). "The first Known Use of Vermillion". Experientia 51 (8): 759–761.  
  13. ^ Petersen, G. (2010). Mining and Metallurgy in Ancient Perú. The Geological Society of America. 
  14. ^ Hayes, A. W. (2008). Principles and Methods of Toxicology (5th ed.). New York, NY, USA: Informa Healthcare.  
  15. ^ "New World's Oldest". Time Magazine. Jul 29, 1957. 
  16. ^ Healy, Paul F.; Marc G. Blainey (2011). "Ancient Maya Mosaic Mirrors: Function, Symbolism, And Meaning". Ancient Mesoamerica (Cambridge University Press) (22): 229–244.   Page 230.
  17. ^ R. V. Dietrich (2005). "Cinnabar". Gemrocks: Ornamental & Curio Stones. University Michigan. 
  18. ^ Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego, CA, USA: Academic Press.  

External links

  • MSDS for cinnabar
  • Dartmouth Toxic Metals Research Program – Mercury
  • Cinnabar visual reference
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