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Realgar

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Formula:
As4S4
System:
Monoclinic
Colour:
Dark red to orange-red
Lustre:
Resinous, Greasy
Hardness:
1½ - 2
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.

Visit gemdat.org for gemological information about Realgar.

Classification of Realgar

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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Physical Properties of Realgar

Resinous, Greasy
Diaphaneity (Transparency):
Transparent
Colour:
Dark red to orange-red
Streak:
Orange-red to red
Hardness (Mohs):
1½ - 2
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)

Crystallography of Realgar

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 Volume:
V 799.54 ų (Calculated from Unit Cell)
Z:
16
Morphology:
Prismatic
Twinning:
Contact twins on {100}

Crystallographic forms of Realgar

Crystal Atlas:
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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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Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
Image Loading

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

Optical Data of Realgar

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 Realgar

Formula:
As4S4
Essential elements:
All elements listed in formula:

Relationship of Realgar to other Species

2.FA.05DuranusiteAs4S
2.FA.10DimorphiteAs4S3
2.FA.15bPararealgarAs4S4
2.FA.15cUM1970-19-S:AsAs4S4
2.FA.15dUM1970-18-S:AsAs4S4
2.FA.20AlacrániteAs8S9
2.FA.25UzoniteAs4S5
2.FA.30LaphamiteAs2(Se,S)3
2.FA.30OrpimentAs2S3
2.FA.35GetchelliteAsSbS3
2.FA.40Wakabayashilite[(As,Sb)6S9][As4S5]
3.7.1PatróniteVS4
3.7.2DuranusiteAs4S
3.7.3DimorphiteAs4S3
3.7.5PararealgarAs4S4
3.7.6AlacrániteAs8S9
3.7.7UzoniteAs4S5
3.7.8OrpimentAs2S3
3.7.9Jeromite
3.7.10LaphamiteAs2(Se,S)3
3.7.11GetchelliteAsSbS3
3.7.12Wakabayashilite[(As,Sb)6S9][As4S5]
3.7.13PääkköneniteSb2AsS2
3.7.14StibniteSb2S3
3.7.15MetastibniteSb2S3
3.7.16TellurantimonySb2Te3
3.7.17BismuthiniteBi2S3
3.7.18NevskiteBi(Se,S)
3.7.19GuanajuatiteBi2Se3
3.7.21IkunoliteBi4(S,Se)3
3.7.22LaitakariteBi4Se2S
3.7.23PoubaitePbBi2(Se,Te,S)4
3.7.24TellurobismuthiteBi2Te3
3.7.25SoučekitePbCuBi(S,Se)3
3.7.26TsumoiteBiTe
3.7.27PilseniteBi4Te3
3.7.28HedleyiteBi7Te3
3.7.29TetradymiteBi2Te2S
3.7.30JoséiteBi4TeS2
3.7.31Joséite-BBi4Te2S
3.7.32IngoditeBi2TeS
3.7.33SulphotsumoiteBi3Te2S
3.7.34KawazuliteBi2Te2Se
3.7.36SkippeniteBi2TeSe2
3.7.37KochkaritePbBi4Te7
3.7.38Rucklidgeite(Bi,Pb)3Te4
3.7.39AleksitePbBi2Te2S2
3.7.40JunoiteCu2Pb3Bi8(S,Se)16

Other Names for Realgar

Name in Other Languages:
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

Other Information

Special Storage/
Display Requirements:
Decomposes to pararealgar with exposure to orange light.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Realgar

Reference List:
Acta Crystallographica: 5: 775-782.

Palache, Charles, Harry Berman & Clifford Frondel (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.

Weigl, O. (1925): XVIII. Der photochemische Zerfall des Realgars. Z. Kristallogr. 38, 288-308.

Zeitschrift für Kristallographie: 136: 48-65.

American Mineralogist (1972): 57: 524.

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.

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.

Internet Links for Realgar

Specimens:
The following Realgar specimens are currently listed for sale on minfind.com.

Localities for Realgar

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.
Mineral and/or Locality  
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