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Realgar

This page kindly sponsored by Douglas Merson
Formula:
As4S4
Colour:
Dark red to orange-red
Lustre:
Resinous, Greasy
Hardness:
1½ - 2
Specific Gravity:
3.56
Crystal System:
Monoclinic
Name:
From Arabic "rahj al-gahr", powder of the mine. Known as a mineral pigment in Byzantium (essentially Asia Minor and the Balkan Peninsula) at least by the beginning of the thirteenth century and presumably having a name by that time. An old realgar locality on the Balkan Peninsula is found at Allchar, Republic of Macedonia.
Alters to pararealgar on exposure to light.

Visually similar to sarabauite and other red arsenic-sulphur minerals.

Visit gemdat.org for gemological information about Realgar.


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Classification of RealgarHide

Approved, 'Grandfathered' (first described prior to 1959)
2.FA.15a

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
F : Sulfides of arsenic, alkalies; sulfides with halide, oxide, hydroxide, H2O
A : With As, (Sb), S
2.8.21.1

2 : SULFIDES
8 : AmXp, with m:p = 1:1
3.7.4

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
7 : Sulphides etc. of V, As, Sb and Bi

Physical Properties of RealgarHide

Resinous, Greasy
Transparency:
Transparent
Colour:
Dark red to orange-red
Streak:
Orange-red to red
Hardness:
1½ - 2 on Mohs scale
Tenacity:
Sectile
Cleavage:
Distinct/Good
Good on {010}, less good on {100}, {101}, {120}, {110}
Density:
3.56 g/cm3 (Measured)    3.59 g/cm3 (Calculated)

Optical Data of RealgarHide

Type:
Biaxial (-)
RI values:
nα = 2.538 nβ = 2.684 nγ = 2.704
2V:
Measured: 40° , Calculated: 38°
Max Birefringence:
δ = 0.166
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
Type:
Anisotropic
Anisotropism:
Strong
Dispersion:
relatively strong
Colour in reflected light:
gray white
Internal Reflections:
yellow to red
Pleochroism:
Visible
Comments:
Nearly colourless to pale golden yellow.

Chemical Properties of RealgarHide

Formula:
As4S4
IMA Formula:
AsS

Crystallography of RealgarHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 9.325(3) Å, b = 13.571(5) Å, c = 6.587(3) Å
β = 106.43°
Ratio:
a:b:c = 0.687 : 1 : 0.485
Unit Cell V:
799.54 ų (Calculated from Unit Cell)
Z:
16
Morphology:
Prismatic
Twinning:
Contact twins on {100}

Crystallographic forms of RealgarHide

Crystal Atlas:
Image Loading
Click on an icon to view
Realgar no.33 - Goldschmidt (1913-1926)
Realgar - Highly modified
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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X-Ray Powder DiffractionHide

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Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Synonyms of RealgarHide

Other Language Names for RealgarHide

Catalan:Realgar
Czech:Realgar
Dutch:Realgaar
Hungarian:Realgár
Italian:Realgar
Japanese:鶏冠石
Lithuanian:Realgaras
Low Saxon:Realgar
Polish:Realgar
Portuguese:Realgar
Romanian:Realgar
Simplified Chinese:雄黄
Slovak:Realgár
Swedish:Realgar

Common AssociatesHide

Associated Minerals Based on Photo Data:
Orpiment314 photos of Realgar associated with Orpiment on mindat.org.
Calcite241 photos of Realgar associated with Calcite on mindat.org.
Quartz187 photos of Realgar associated with Quartz on mindat.org.
Arsenic168 photos of Realgar associated with Arsenic on mindat.org.
Baryte102 photos of Realgar associated with Baryte on mindat.org.
Sphalerite76 photos of Realgar associated with Sphalerite on mindat.org.
Stibnite70 photos of Realgar associated with Stibnite on mindat.org.
Pyrite69 photos of Realgar associated with Pyrite on mindat.org.
Pararealgar57 photos of Realgar associated with Pararealgar on mindat.org.
Galena43 photos of Realgar associated with Galena on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

2.FA.AnorpimentAs2S3Tric. 1 : P1
2.FA.BonazziiteAs4S4Mon. 2/m : B2/b
2.FA.05DuranusiteAs4SOrth. mmm (2/m 2/m 2/m) : Pmna
2.FA.10DimorphiteAs4S3Orth. mmm (2/m 2/m 2/m) : Pnma
2.FA.15bPararealgarAs4S4Mon. 2/m : P21/b
2.FA.15dUM1970-18-S:AsAs4S4Mon. 2/m : B2/b
2.FA.20AlacrániteAs8S9Mon. 2/m : P2/b
2.FA.25UzoniteAs4S5Mon.
2.FA.30LaphamiteAs2(Se,S)3Mon. 2/m
2.FA.30OrpimentAs2S3Mon. 2/m
2.FA.35GetchelliteAsSbS3Mon. 2/m : P21/b
2.FA.40Wakabayashilite[(As,Sb)6S9][As4S5]Orth. mm2 : Pna21

Related Minerals - Dana Grouping (8th Ed.)Hide

2.8.21.1Platynite
2.8.21.2PararealgarAs4S4Mon. 2/m : P21/b
2.8.21.3UM1970-18-S:AsAs4S4Mon. 2/m : B2/b
2.8.21.4UM1970-19-S:AsAs4S4Mon. 2/m : B2/b

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

3.7.1PatróniteVS4Mon.
3.7.2DuranusiteAs4SOrth. mmm (2/m 2/m 2/m) : Pmna
3.7.3DimorphiteAs4S3Orth. mmm (2/m 2/m 2/m) : Pnma
3.7.5PararealgarAs4S4Mon. 2/m : P21/b
3.7.6AlacrániteAs8S9Mon. 2/m : P2/b
3.7.7UzoniteAs4S5Mon.
3.7.8OrpimentAs2S3Mon. 2/m
3.7.9JeromiteAmor.
3.7.10LaphamiteAs2(Se,S)3Mon. 2/m
3.7.11GetchelliteAsSbS3Mon. 2/m : P21/b
3.7.12Wakabayashilite[(As,Sb)6S9][As4S5]Orth. mm2 : Pna21
3.7.13PääkköneniteSb2AsS2Mon. 2/m : B2/m
3.7.14StibniteSb2S3Orth. mmm (2/m 2/m 2/m)
3.7.15MetastibniteSb2S3Amor.
3.7.16TellurantimonySb2Te3Trig.
3.7.17BismuthiniteBi2S3Orth. mmm (2/m 2/m 2/m)
3.7.18NevskiteBi(Se,S)Trig.
3.7.19GuanajuatiteBi2Se3Orth. mmm (2/m 2/m 2/m) : Pnma
3.7.21IkunoliteBi4(S,Se)3Trig.
3.7.22LaitakariteBi4Se2STrig. 3m : R3m
3.7.23PoubaitePbBi2(Se,Te,S)4Trig.
3.7.24TellurobismuthiteBi2Te3Trig.
3.7.25SoučekitePbCuBi(S,Se)3Orth.
3.7.26TsumoiteBiTeTrig. 3m (3 2/m) : P3 1m
3.7.27PilseniteBi4Te3Trig. 3m (3 2/m) : R3m
3.7.28HedleyiteBi7Te3Trig. 3m (3 2/m) : R3m
3.7.29TetradymiteBi2Te2STrig. 3m (3 2/m) : R3m
3.7.30JoséiteBi4TeS2Trig. 3m (3 2/m) : R3m
3.7.31Joséite-BBi4Te2STrig.
3.7.32IngoditeBi2TeSTrig.
3.7.33SulphotsumoiteBi3Te2STrig.
3.7.34KawazuliteBi2Te2SeTrig.
3.7.36SkippeniteBi2TeSe2Trig.
3.7.37KochkaritePbBi4Te7Trig.
3.7.38RucklidgeitePbBi2Te4Trig.
3.7.39AleksitePbBi2Te2S2Trig.
3.7.40JunoiteCu2Pb3Bi8(S,Se)16Mon. 2/m : B2/m

Other InformationHide

Special Storage/
Display Requirements:
Decomposes to orange pararealgar with exposure to light.
Health Risks:
Contains arsenic - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.

References for RealgarHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Weigl, O. (1925) XVIII. Der photochemische Zerfall des Realgars. Zeitschrift für Kristallographie: 38: 288-308.
Ito, T., Morimoto, N., Sadanaga, R. (1952) The crystal structure of realgar. Acta Crystallographica: 5: 775-782.
Palache, C., Berman, H., Frondel, C. (1944) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume I: Elements, Sulfides, Sulfosalts, Oxides. John Wiley and Sons, Inc., New York. 7th edition, revised and enlarged, 834pp.: 255-258.
Mullen, D.J.E., Nowacki, W. (1972) Refinement of the crystal structures of realgar, AsS and orpiment, As2S3. Zeitschrift für Kristallographie: 136: 48-65.
Yu, S.C., Zoltai, T. (1972) Crystallography of a high-temperature phase of realgar. American Mineralogist: 57: 1873.
Douglass, D.L., Shing, C., Wang, G. (1992) The light-induced alteration of realgar to pararealgar. American Mineralogist: 77: 1266-1274.
Frost, R.L., Martens, W.N., Kloprogge, J.T. (2002) Raman spectroscopic study of cinnabar (HgS), realgar (As4S4), and orpiment (As2S3) at 298 and 77K. Neues Jahrbuch für Mineralogie, Monatshefte: 2002: 469-480.
Kyono, A., Kimata, M., Hatta, T. (2005) Light-induced degradation dynamics in realgar: In situ structural investigation using single-crystal X-ray diffraction study and X-ray photoelectron spectroscopy. American Mineralogist: 90: 1563-1570.
Ballirano, P., Maras, A. (2006) In-situ X-ray transmission powder diffraction study of the kinetics of the light induced alteration of realgar (alpha-As4S4). European Journal of Mineralogy: 18: 589–599.
Bonazzi, P., Bindi, L., Pratesi, G., Menchetti, S. (2006) Light-induced changes in molecular arsenic sulfides: State of the art and new evidence by single-crystal X-ray diffraction. American Mineralogist: 91: 1323-1330.
Naumov, P., Makreski, P., Jovanovski, G. (2007) Direct atomic scale observations of linkage isomerization of As4S4 clusters during the photoinduced transition of realgar to pararealgar. Inorganic Chemistry: 46: 10624-10631.
Bonazzi, P., Bindi, L. (2008) A crystallographic review of arsenic sulfides: Effects of chemical variations and changes induced by exposure to light. Zeitschrift für Kristallographie: 223: 132-147.
Kyono, A. (2009) Molecular conformation and anion configuration variations for As4S4 and As4Se4 in an anion-substituted solid solution. American Mineralogist: 94: 451-460.
Ballirano, P. (2012) Thermal behavior of realgar As4S4, and of arsenolite As2O3 and non-stoichiometric As8S8+x crystals produced from As4S4 melt recrystallization. American Mineralogist: 97: 1320-1329.
Pratesi, G., Zoppi, M. (2015) An insight into the inverse transformation of realgar altered by light. American Mineralogist: 100: 1222-1229.

Internet Links for RealgarHide

Localities for RealgarHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListShow

Mineral and/or Locality  
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