Light-induced variations in realgar and beta -As<sub>4</sub>S<sub>4</sub>; X-ray diffraction and Raman studies

Bonazzi, Paola; Menchetti, Silvio; Pratesi, Giovanni; Muniz‐Miranda, Maurizio; Sbrana, G.

doi:10.2138/am-1996-7-810

Cited by 82 publications

(76 citation statements)

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“…FIGURE 4. Unit-cell volume vs. the S content (atoms per As 4 unit); empty circles refer to As 8 S 9-x compounds (Kothiyal and Ghosh 1976;Bonazzi et al 2003); filled circles refer to alacranite from Kamchatka (Popova et al 1986; this study); diamonds: synthetic b-As 4 S 4 (Porter and Sheldrick 1972;Bonazzi et al 1996); square: synthetic As 4 S 5 (Whitfield 1973a); empty up-triangle and star refer to a-dimorphite (Whitfield 1970) and b-dimorphite (Whitfield 1973b), respectively; down-triangle refers to duranusite (Márquez-Zavalía et al 1999). Data fit the regression line: y = 407.6 + 99.6x; r = 0.992.…”

Section: Crystal Chemical Remarksmentioning

confidence: 87%

“…For this reason, the mineral was named alacranite. However, the lattice parameters of alacranite resemble barely those of the natural b-phase from Alacràn (Clark 1970) and those of synthetic bAs 4 S 4 (Porter and Sheldrick 1972;Bonazzi et al 1996). In particular, alacranite exhibits a greater unit-cell volume, in keeping with the different chemical composition.…”

Section: Introductionmentioning

confidence: 95%

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Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Bonazzi

Bindi

Попова

et al. 2003

American Mineralogist

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Alacranite from the type locality (Uzon caldera, Kamchatka, Russian Federation) was submitted for structural analysis. A single crystal was selected and the following lattice parameters were determined: a = 9.942(4), b = 9.601(2), c = 9.178(3) Å, b = 101.94(3)∞, V = 857.1 (5) Å 3 . The crystal structure was solved in the P2/c space group using direct methods and refined to R = 6.79% for 472 observed reflections. The structure of alacranite consists of an ordered sequence of As 4 S 4 and As 4 S 5 cage-like molecules, with a molecular packing closely resembling that found in the b-As 4 S 4 phase. Both As-As and As-S intramolecular distances are in the range usually observed for covalent bonds. The structural model confirms the chemical formula As 8 S 9 for alacranite, and accounts for differences in the unit-cell parameters of alacranite compared to those of the natural analogue of b-As 4 S 4 . This latter mineral, therefore, should receive a new name.

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Section: Crystal Chemical Remarksmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 95%

Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Bonazzi

Bindi

Попова

et al. 2003

American Mineralogist

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“…Based on the comparison of our spectra with the ones obtained by Georgiev et al [22], the quenching temperature for C90.058 and C90.094 could be around 450°C and 550°C for C90.101. According to Bonazzi et al [24] and Grundmann et al [18], the As 4 S 4 monomer units present in the arsenic sulfide glass most likely correspond to a mid-state between the As 4 S 4 β -phase and the As 4 S 4 χ -phase because of broader bands observed at 219, 235 and 245 cm −1 than expected for the more molecular ordered realgar or β -phase. Even though Raman spectroscopy was very helpful for identifying the type of arsenic sulfide used in the decorative panels of the Japanese tower as arsenic sulfide glass, this technique does not provide any information on the starting materials.…”

Section: Mrsmentioning

confidence: 99%

Identification of artificial orpiment in the interior decorations of the Japanese tower in Laeken, Brussels, Belgium

2015

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In this paper, we used a multi-technique approach in order to identify the arsenic sulfide pigment used in the decorative panels of the Japanese tower in Laeken, Belgium. Our attention was drawn to this particular pigment because of its relatively good conservation state, despite its known tendency to fade over time when exposed to light. The pigment was used with different painting techniques, bound with oil and urushi in the lacquers and with an aqueous binder in the mat relief panels. In the latter case it is always applied as an underlayer mixed with ultramarine blue. This quite unusual pigment mixture also shows a good state of preservation. In this study, the orpiment used for the Japanese tower has been identified as an amorphous arsenic sulfide glass (As x S x ) with the aid of light microscopy, PLM, SEM-EDX and Raman microscopy. The pigment features different degrees of As 4 S 4 monomer units in its structure, also known as realgar-like nano-phases. This most likely indicates different synthesis processes as the formation of these As 4 S 4 monomers is dependent of the quenching temperature (Tq) to which the artificial pigment is exposed during the preparation phase.

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“…It is long known that both polychromatic and monochromatic light alter realgar and the -phase up to pararealgar through an intermediate product ( -phase) (Douglass et al, 1992;Bonazzi et al, 1996;Muniz-Miranda et al, 1996). The light-induced formation of the -phase obtained from the -phase occurs with a strong anisotropic increase of the unit-cell volume.…”

Section: Introductionmentioning

confidence: 99%

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

Bonazzi¹,

Bindi²,

Olmi³

et al. 2003

ejm

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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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Light-induced variations in realgar and beta -As₄S₄; X-ray diffraction and Raman studies

Cited by 82 publications

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Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Identification of artificial orpiment in the interior decorations of the Japanese tower in Laeken, Brussels, Belgium

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

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Light-induced variations in realgar and beta -As4S4; X-ray diffraction and Raman studies

Cited by 82 publications

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Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Alacranite, As8S9: structural study of the holotype and re-assignment of the original chemical formula

Identification of artificial orpiment in the interior decorations of the Japanese tower in Laeken, Brussels, Belgium

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

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Light-induced variations in realgar and beta -As₄S₄; X-ray diffraction and Raman studies