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Orpiment

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Formula:
As2S3
Colour:
Orange-yellow to lemon-yellow
Lustre:
Pearly
Hardness:
1½ - 2
Specific Gravity:
3.49
Crystal System:
Monoclinic
Name:
From Latin "aurum", gold, and "pigmentum", pigment, in allusion to its color.
Isostructural with:
May be visually similar to uzonite.


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Classification of OrpimentHide

Approved, 'Grandfathered' (first described prior to 1959)
2.FA.30

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
2.11.1.1

2 : SULFIDES
11 : AmBnXp, with (m+n):p = 2:3
3.7.8

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

Pronounciation of OrpimentHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of OrpimentHide

Pearly
Transparency:
Transparent
Colour:
Orange-yellow to lemon-yellow
Streak:
Light lemon yellow
Hardness:
1½ - 2 on Mohs scale
Tenacity:
Sectile
Cleavage:
Perfect
Perfect {010} imperfect {100}
Density:
3.49 g/cm3 (Measured)    3.48 g/cm3 (Calculated)

Optical Data of OrpimentHide

Type:
Biaxial (-)
RI values:
nα = 2.400 nβ = 2.810 nγ = 3.020
2V:
Measured: 30° to 76°, Calculated: 62°
Max Birefringence:
δ = 0.620
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High
Type:
Anisotropic
Anisotropism:
Barely observable because of strong internal reflections
Dispersion:
relatively strong r > v
Reflectivity:
400nmR1=33.0%R2= 36.5%
420nmR1=31.0%R2= 35.2%
440nmR1=28.9%R2= 33.9%
460nmR1=27.4%R2= 31.5%
480nmR1=26.0%R2= 30.3%
500nmR1=24.9%R2= 29.3%
520nmR1=24.0%R2= 28.4%
540nmR1=23.3%R2= 27.8%
560nmR1=22.8%R2= 27.3%
580nmR1=22.3%R2= 26.9%
600nmR1=22.0%R2= 26.5%
620nmR1=21.7%R2= 26.3%
640nmR1=21.5%R2= 26.0%
660nmR1=21.2%R2= 25.7%
680nmR1=21.0%R2= 25.5%
700nmR1=20.8%R2= 25.3%

Reflectance graph
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 36.5%.
R1 shown in black, R2 shown in red
Colour in reflected light:
White to pale grey
Internal Reflections:
Strong
Pleochroism:
Strong
Comments:
white to grey-white with a reddish tint (reflected light)
Y=yellow, Z=greenish yellow (transmitted light)

Chemical Properties of OrpimentHide

Formula:
As2S3
Common Impurities:
Hg,Ge,Sb

Crystallography of OrpimentHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Cell Parameters:
a = 11.475(5) Å, b = 9.577(4) Å, c = 4.256(2) Å
β = 90.45(5)°
Ratio:
a:b:c = 1.198 : 1 : 0.444
Unit Cell V:
467.70 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Commonly in foliated columnar or fibrous aggregates, with cleavages as much as 60 cm across; may be reniform or botryoidal; also granular or powdery; rarely as prismatic crystals.
Twinning:
On {100}
Comment:
sp. gr. P21/n

Crystallographic forms of OrpimentHide

Crystal Atlas:
Image Loading
Click on an icon to view
Orpiment no.3 - Goldschmidt (1913-1926)
Orpiment no.13 - Goldschmidt (1913-1926)
Orpiment - Tabular {010}
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
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X-Ray Powder DiffractionHide

Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.
Powder Diffraction Data:
d-spacingIntensity
4.85 (100)
4.02 (50)
3.22 (30)
2.79 (30)
2.72 (30)
2.47 (40)
1.755 (40)
Comments:
Baia Sprie (Felsőbánya), Romania.

Synonyms of OrpimentHide

Other Language Names for OrpimentHide

Common AssociatesHide

ArsenicAs
BaryteBaSO4
CalciteCaCO3
GypsumCaSO4 · 2H2O
RealgarAs4S4
StibniteSb2S3
Associated Minerals Based on Photo Data:
Realgar314 photos of Orpiment associated with Realgar on mindat.org.
Baryte196 photos of Orpiment associated with Baryte on mindat.org.
Hutchinsonite102 photos of Orpiment associated with Hutchinsonite on mindat.org.
Calcite75 photos of Orpiment associated with Calcite on mindat.org.
Quartz69 photos of Orpiment associated with Quartz on mindat.org.
Getchellite39 photos of Orpiment associated with Getchellite on mindat.org.
Pyrite30 photos of Orpiment associated with Pyrite on mindat.org.
Chalcopyrite23 photos of Orpiment associated with Chalcopyrite on mindat.org.
Lorándite21 photos of Orpiment associated with Lorándite on mindat.org.
Picropharmacolite18 photos of Orpiment associated with Picropharmacolite 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.15aRealgarAs4S4Mon. 2/m
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.35GetchelliteAsSbS3Mon. 2/m : P21/b
2.FA.40Wakabayashilite[(As,Sb)6S9][As4S5]Orth. mm2 : Pna21

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

2.11.1.2GetchelliteAsSbS3Mon. 2/m : P21/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
3.7.4RealgarAs4S4Mon. 2/m
3.7.5PararealgarAs4S4Mon. 2/m : P21/b
3.7.6AlacrániteAs8S9Mon. 2/m : P2/b
3.7.7UzoniteAs4S5Mon.
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

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

References for OrpimentHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Buerger, M.J. (1942) The unit cell and space group of orpiment. American Mineralogist: 27: 301-304.
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: 266-269.
Morimoto, N. (1954) The crystal structure of orpiment (As2S3) refined. Mineralogical Journal: 1: 160-169.
Evans, B.L., Young, P.A. (1967) Optical properties of arsenic trisulphide. Proceedings of the Royal Society of London: A297: 230-243.
Zallen, R., Slade, M.L., Ward, A.T. (1971) Lattice vibrations and interlayer interactions in crystalline As2S3 and As2Se3. Physical Review B: 3: 4257-4273.
Mullen, D.J.E., Nowacki, W. (1972) Refinement of the crystal structures of realgar, AsS and orpiment, As2S3. Zeitschrift für Kristallographie: 136: 48-65.
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: 469-480.
Espeau, P., Tamarit, J.L., Barrio, M., López, D.Ó., Perrin, M.A., Allouchi, H., Céolin, R. (2006) Solid state studies on synthetic and natural crystalline arsenic(III) sulfide, As2S3 (Orpiment): New data for an old compound. Chemistry of Materials: 18: 3821-3826.
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.
Gibbs, G.V., Wallace, A.F., Zallen, R., Downs, R.T., Ross, N.L., Cox, D.F., Rosso, K.M. (2010) Bond paths and van der Waals interactions in orpiment, As2S3. Journal of Physical Chemistry: A 114: 6550-6557.
Srivastava, P., Mund, H.S., Sharma, Y. (2011) Investigation of electronic properties of crystalline arsenic chalcogenides: Theory and experiments. Physica B: 406: 3083-3088.

Internet Links for OrpimentHide

Localities for OrpimentHide

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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