Cinnabar structure

HgS is polymorphic. The red a-form is the mineral cinnabar, or vermilion, which has a distorted rock-salt structure and can be prepared from the elements. )3-HgS is the rare, black, mineral metacinnabar which has the zinc-blende structure and is converted by heat to the stable a-form. In the laboratory the most familiar form is the highly insoluble black precipitate obtained by the action of HzS on aqueous solutions of Hg. HgS is an unreactive substance, being attacked only by cone HBr, HI or aqua regia. HgSe and... 

Figure 2 Calculated Hg L3-edge specu a (a) at 1.5 GPa with hypothetical zincblende (full line) and cinnabar (dashed line) structures (b) at 8GPa with hypothetical cinnabar (dashed line) and rocksalt (full line) structures.

In cinnabar, HgS, the sulfur atom has a normal-valence structure, in which it forms two bonds with mercury atoms. The Hg—S—Hg bond angle is 105°. The mercury atom may be described as forming two oppositely directed bonds with use of two sp hybrid bond orbitals the value of the S—Hg—S angle is 172°. The bond length, 2.36 A, leads,... 

Mercuric sulfide (HgS) is dimorphic. The more common form, cinnabar (red a-form), has a distorted RS, trigonal structure which is unique among the monosulfides, for the crystal is built of helical chains in which Hg has two nearest neighbors at 2.36 A, two more at 3.10 A, and two at 3.30 A. Bulk a-HgS is a large-gap semiconductor (2.1 eV), transparent in the red and near IR bands. The rare, black mineral metacinnabarite is the 3-HgS polymorph with a ZB structure, in which Hg forms tetrahedral bonds. Upon heating, 3-HgS is converted to the stable a-form. The ZB structure of HgS is stabilized under a few percent admixture of transition metals, which replace Hg ions in the lattice. 

Vermilion and cinnabar are two bright red, toxic minerals that share an identical composition (they are both composed of mercury sulfide) but have different crystal structures. Two kinds of vermilion are known one of natural origin and another made artificially. Finely ground natural vermilion may vary in hue from red to liver-brown and even to black. Artificial vermilion was made from mercury and sulfur the method of preparation seems to have been developed by the Chinese and was introduced into Europe only during the eighth century c.e. (Gettens et al. 1972). 

Mercury(II) sulfide, HgS, is dimorphic. Metacinnabarite, a rare mineral, is obtained by precipitation from aqueous acidified mercury(II) chloride by H2S.351 It crystallizes in the zinc blende structure in which HgK forms tetrahedral bonds (Hg—S = 253pm) it is stable above 400 °C.352 The more common form, cinnabar, is obtained from the elements or by passing H2S into mercury(II) acetate in hot glacial acetic acid containing NH4SCN.351 It crystallizes in the space group P 3221 and consists of infinite —Hg—S—Hg—S— chains spirally wound on axes... 

The presence of pyrrolizidine alkaloids in arctiid moths that had been reared on Senecio and Crotalaria species has been established by Rothschild et al.4S These alkaloids are stored in the moths, and serve as a deterrent to vertebrate predators and as precursors for insect sex pheromones. A pyrrolizidine alkaloid metabolite from the Cinnabar moth (Tyria jacobaea L.), named callimorphine, has been shown to have the structure (49) on the basis of mass-spectral and degradative evidence.46 The structure (49) was confirmed by synthesis of callimorphine and a diastereo-isomer by treatment of 9-chlororetronecine with the sodium salt of ( )-2-acetoxy-2-methylbutanoic acid. 

The addition of H2S or alkali metal sulfides to aqueous Hg2+ precipitates the highly insoluble, black mercuric sulfide, HgS. This black solid when heated or treated in other ways is changed into a red form that is identical to the mineral cinnabar. In this red form, HgS has a distorted NaCl structure in which (Hg—S) , chains can be recognized. Red cinnabar on irradiation in aqueous KI is converted to black cinnabar, which has the ZnS structure and also occurs in Nature. 

Mercury (I I) sulphide, HgS, exists in both zinc-blende and rock-salt structures, the red, hexagonal cinnabar, s.g. 8.18, being the stable and common form the metastable, black, cubic metacinnabar, s.g. 7.60, is rare. Mercury(I) sulphide is unknown. 

Many less common elements (e.g. Ga and Ge) are incorporated to some extent into the crystal structures of major minerals, and thus may be rather thinly spread over the crust. Others are concentrated by forming individual minerals. Native gold and cinnabar (HgS) were known in antiquity although Au and Hg are very rare elements. On the other hand, the less rare Ga and Ge were not discovered until the late 19th century. 

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