The crystal structure of pararealgar, As<sub>4</sub>S<sub>4</sub>

Bonazzi, Paola; Menchetti, Silvio; Pratesi, Giovanni

doi:10.2138/am-1995-3-422

Cited by 73 publications

(52 citation statements)

References 9 publications

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“…Realgar, a widely used orange/red pigment, occurs in low-temperature hydrothermal deposits [3][4][5]. Pararealgar is the light-induced degradation yellow form of realgar and alacranite [6,7]. Mixtures of pararealgar and/or realgar have been systematically observed in many studies [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Synthetic arsenic sulfides in Japanese prints of the Meiji period

et al. 2016

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A multi-analytical investigation of Japanese woodblock prints ranging in date from 1864 to 1895 and covering essentially the time span between the very end of the Edo period and the middle of the Meiji period showed a widespread use of arsenic sulfides for yellow and green colored areas (the latter obtained by mixing Prussian blue to the yellow arsenic sulfides). Analysis by optical microscopy, X-ray fluorescence spectroscopy, Raman microscopy, and Scanning Electron Microscopy confirmed that the yellow pigment is usually a compound belonging to the solid solution series (As 8 S 8 )-(As 8 S 9 ). The poor crystallinity of the pigment as shown by Raman microscopy, the non-stoichiometric As/S ratio, as well as the presence of excess uncombined sulfur point to a synthetic origin for the pigment. Period literary sources suggest that synthetic arsenic sulfide pigments manufacture might have started in the Iwashiro province in 1846. This is to our knowledge the first conclusive evidence for the use of synthetic arsenic sulfides in woodblock prints in Japan.

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Section: Introductionmentioning

confidence: 99%

Synthetic arsenic sulfides in Japanese prints of the Meiji period

et al. 2016

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“…Realgar is the low-temperature form, -As 4 S 4 (Hall, 1966;Clark, 1970;Roland, 1972;Blachnik et al, 1980;Bryndzya & Kleppa, 1988), which commonly occurs as a sublimation product in active volcanic areas, in low-temperature hydrothermal deposits, and, to a lesser extent, as a minor constituent of lead, silver, and gold ore veins. Pararealgar occurs as a yellow film covering realgar crystals which have been exposed to light (Roberts et al, 1980;Bonazzi et al, 1995). The -As 4 S 4 phase is the high-temperature form, stable in the system As-S at temperatures higher than 256 5°C (Hall, 1966).…”

Section: Introductionmentioning

confidence: 99%

How many alacranites do exist? A structural study of non-stoichiometric As8S9-x crystals

Bonazzi¹,

Bindi²,

Olmi³

et al. 2003

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Crystals of arsenic sulphide (reported as alacranite), coming from the burning dump of KateÏ rina Mine (Czech Republic), have been investigated by single crystal X-ray diffraction and chemical microanalysis.Both analytical data and unit-cell parameters strongly suggest the existence of a continuous series between the high-temperature polymorph ( -As 4 S 4 ) and the mineral alacranite (As 8 S 9 ). As the S content increases in the series, the unit-cell volume increases accordingly. The structural model has been obtained for two crystals, exhibiting different unit-cell volumes (ALA15: a = 9.940(2), b = 9.398(2), c = 9.033(2), =102.12(2), V = 825.0(3), R obs = 6.12 %; ALA2: a = 9.936(2), b = 9.458(2), c = 9.106(2), = 101.90(2), V = 837.3(3), R obs = 6.41 %). We found that the non-stoichiometric compounds crystallize as a disordered mixture of two kinds of cage-like molecules, packed together as in the -As 4 S 4 phase. The first one is identical to the As 4 S 4 molecule found in the structures of both realgar ( -As 4 S 4 ) and -As 4 S 4 . The second molecule is chemically and structurally identical to that found in the As 4 S 5 compound. The simultaneous presence of As 4 S 4 (C2/c) and As 8 S 9 (P2/c) microdomains could be a reason for the observed gradual change of the translation symmetry from the -phase to alacranite s.s..

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“…Realgar polymorphs (all monoclinic) contain covalently bonded clusters of four arsenic and four sulfur atoms; differences in their crystal structures arise from subtle differences in the arrangement of arsenic and sulfur clusters (29)(30)(31). Huber et al (32) have described a thermophyllic archaeon that respires arsenate and precipitates realgar in its growth range of 68-100°C in laboratory cultures.…”

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“…Orpiment, realgar, and other arsenic sulfide minerals are typical high-temperature phases found together in hydrothermal deposits, but few studies discuss the occurrence of realgar polymorphs at lower temperatures. Pararealgar has been observed as an alteration product of realgar at ambient conditions (31,35). In another study, an arsenic sulfide phase identified as the realgar polymorph alacranite (As 4 S 4 ) was precipitated from solution after acid extraction from sediments (27).…”

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The influence of sulfur and iron on dissolved arsenic concentrations in the shallow subsurface under changing redox conditions

O’Day

Vlassopoulos

Root

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

418

306

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The chemical speciation of arsenic in sediments and porewaters of aquifers is the critical factor that determines whether dissolved arsenic accumulates to potentially toxic levels. Sequestration of arsenic in solid phases, which may occur by adsorption or precipitation processes, controls dissolved concentrations. We present synchrotron x-ray absorption spectra of arsenic in shallow aquifer sediments that indicate the local structure of realgar (AsS) as the primary arsenic-bearing phase in sulfate-reducing conditions at concentrations of 1-3 mmol⅐kg ؊1 , which has not previously been verified in sediments at low temperature. Spectroscopic evidence shows that arsenic does not substitute for iron or sulfur in iron sulfide minerals at the molecular scale. A general geochemical model derived from our field and spectroscopic observations show that the ratio of reactive iron to sulfur in the system controls the distribution of solid phases capable of removing arsenic from solution when conditions change from oxidized to reduced, the rate of which is influenced by microbial processes. Because of the difference in solubility of iron versus arsenic sulfides, precipitation of iron sulfide may remove sulfide from solution but not arsenic if precipitation rates are fast. The lack of incorporation of arsenic into iron sulfides may result in the accumulation of dissolved As(III) if adsorption is weak or inhibited. Aquifers particularly at risk for such geochemical conditions are those in which oxidized and reduced waters mix, and where the amount of sulfate available for microbial reduction is limited. Despite intensive study in recent years, quantitative biogeochemical models that explain and predict conditions controlling the uptake or release of dissolved arsenic in groundwaters remain incomplete, due partly to a lack of knowledge of arsenic speciation in subsurface sediments. Worldwide, elevated concentrations of arsenic (Ͼ10 g⅐liter Ϫ1 , the World Health Organization and new U.S. Environmental Protection Agency drinking-water standard) in groundwater have the potential to have an adverse impact on Ϸ90 million people (1, 2), including 13 million in the United States (3, 4). Arsenic is a known carcinogen and mutagen that can lead to both acute and chronic adverse health effects (5, 6). Arsenic in ground-and surface waters results from both natural and anthropogenic sources, but its mobility and attenuation, and thus impact on humans and other organisms, is directly tied to its chemical speciation (3,7,8).Recent studies using direct spectroscopic characterizations have begun to verify differing chemical states of arsenic in natural samples and their influence on arsenic mobility (9-12). Under oxic conditions, it is widely accepted that arsenic in sediments is removed from solution by adsorption to or coprecipitation with ferric oxyhydroxide and possibly by adsorption to manganese oxide and phyllosilicate minerals (7, 13). As subsurface conditions change from oxidized to progressively more reduced, As(V) is reduced to As(III...

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The crystal structure of pararealgar, As₄S₄

Cited by 73 publications

References 9 publications

Synthetic arsenic sulfides in Japanese prints of the Meiji period

Synthetic arsenic sulfides in Japanese prints of the Meiji period

How many alacranites do exist? A structural study of non-stoichiometric As8S9-x crystals

The influence of sulfur and iron on dissolved arsenic concentrations in the shallow subsurface under changing redox conditions

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The crystal structure of pararealgar, As4S4

Cited by 73 publications

References 9 publications

Synthetic arsenic sulfides in Japanese prints of the Meiji period

Synthetic arsenic sulfides in Japanese prints of the Meiji period

How many alacranites do exist? A structural study of non-stoichiometric As8S9-x crystals

The influence of sulfur and iron on dissolved arsenic concentrations in the shallow subsurface under changing redox conditions

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The crystal structure of pararealgar, As₄S₄