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Realgar

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Formula:
As
 
4
S
 
4
System:MonoclinicColour:Dark red to orange-red
Lustre:Resinous, GreasyHardness: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. Currently in public beta-test.

Classification of Realgar

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:2/F.02-30
Nickel-Strunz 10th (pending) edition ID: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
Dana 8th edition ID:2.8.21.1

2 : SULFIDES
8 : AmXp, with m:p = 1:1
Hey's CIM Ref.: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

Lustre: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 (measured):3.56 g/cm3
Density (calculated):3.59 g/cm3

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}
Crystal Atlas:
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Realgar no.33 - Goldschmidt (1913-1926)
Realgar - Highly modified

About Crystal Atlas

The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. The 3d models and HTML5 code are kindly provided by www.smorf.nl.

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X-Ray Powder Diffraction:
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Radiation - Copper Kα
Data Set:
Horizontal Axis: ° to ° Vertical Axis: % Source Data: Filtered Data:
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°
Maximum Birefringence:δ = 0.166

Chart 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:
As
 
4
S
 
4
Simplified for copy/paste:As4S4
Essential elements:As, S
All elements listed in formula:As, S

Relationship of Realgar to other Species

Related Minerals - Nickel-Strunz Grouping):

- +
2.FA.05Duranusite
As
 
4
S
2.FA.10Dimorphite
As
 
4
S
 
3
2.FA.15bPararealgar
As
 
4
S
 
4
2.FA.15cUM1970-19-S:As
As
 
4
S
 
4
2.FA.15dUM1970-18-S:As
As
 
4
S
 
4
2.FA.20Alacránite
As
 
8
S
 
9
2.FA.25Uzonite
As
 
4
S
 
5
2.FA.30Laphamite
As
 
2
(Se,S)
 
3
2.FA.30Orpiment
As
 
2
S
 
3
2.FA.35Getchellite
AsSbS
 
3
2.FA.40Wakabayashilite
[(As,Sb)
 
6
S
 
9
][As
 
4
S
 
5
]
Related Minerals - Hey's Index Grouping:

- +
3.7.1Patrónite
VS
 
4
3.7.2Duranusite
As
 
4
S
3.7.3Dimorphite
As
 
4
S
 
3
3.7.5Pararealgar
As
 
4
S
 
4
3.7.6Alacránite
As
 
8
S
 
9
3.7.7Uzonite
As
 
4
S
 
5
3.7.8Orpiment
As
 
2
S
 
3
3.7.9Jeromite
3.7.10Laphamite
As
 
2
(Se,S)
 
3
3.7.11Getchellite
AsSbS
 
3
3.7.12Wakabayashilite
[(As,Sb)
 
6
S
 
9
][As
 
4
S
 
5
]
3.7.13Pääkkönenite
Sb
 
2
AsS
 
2
3.7.14Stibnite
Sb
 
2
S
 
3
3.7.15Metastibnite
Sb
 
2
S
 
3
3.7.16Tellurantimony
Sb
 
2
Te
 
3
3.7.17Bismuthinite
Bi
 
2
S
 
3
3.7.18Nevskite
Bi(Se,S)
3.7.19Guanajuatite
Bi
 
2
(Se,S)
 
3
3.7.21Ikunolite
Bi
 
4
(S,Se)
 
3
3.7.22Laitakarite
Bi
 
4
Se
 
2
S
3.7.23Poubaite
PbBi
 
2
(Se,Te,S)
 
4
3.7.24Tellurobismuthite
Bi
 
2
Te
 
3
3.7.25Součekite
PbCuBi(S,Se)
 
3
3.7.26Tsumoite
BiTe
3.7.27Pilsenite
Bi
 
4
Te
 
3
3.7.28Hedleyite
Bi
 
7
Te
 
3
3.7.29Tetradymite
Bi
 
2
Te
 
2
S
3.7.30Joséite
Bi
 
4
TeS
 
2
3.7.31Joséite-B
Bi
 
4
Te
 
2
S
3.7.32Ingodite
Bi
 
2
TeS
3.7.33Sulphotsumoite
Bi
 
3
Te
 
2
S
3.7.34Kawazulite
Bi
 
2
Te
 
2
Se
3.7.36Skippenite
Bi
 
2
TeSe
 
2
3.7.37Kochkarite
PbBi
 
4
Te
 
7
3.7.38Rucklidgeite
(Bi,Pb)
 
3
Te
 
4
3.7.39Aleksite
PbBi
 
2
Te
 
2
S
 
2
3.7.40Junoite
Cu
 
2
Pb
 
3
Bi
 
8
(S,Se)
 
16

Other Names for Realgar

Synonyms:
EoliteRealgariteRed ArsenicRed OrpimentRisigallo
RisigallumRuby SulfurRuby SulphurSandaracha
Other Languages:
Catalan:Realgar
Czech:Realgar
Dutch:Realgaar
French:Réalgar
Arsenic Rouge
German:Realgar
Eolit
Realgarit
Greek:Σανδαράκη
Σανδαραχη
Hungarian:Realgár
Italian:Realgar
Japanese:鶏冠石
Lithuanian:Realgaras
Low Saxon:Realgar
Polish:Realgar
Portuguese:Realgar
Romanian:Realgar
Russian:Реальгар
Simplified Chinese:雄黄
Slovak:Realgár
Spanish:Rejalgar
Eolita
Realgarita
Swedish:Realgar

Other Information

Health Warning:Contains arsenic - always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest.

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.

Mindat.org articles about Realgar

Article entries:
The Extraction Of Arsenic From RealgarDavid Aldridge

Internet Links for Realgar

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