Mineralogy Database

Orpiment Mineral Data

Search Webmineral :

General Orpiment Information

Help on Chemical  Formula: Chemical Formula: As2S3
Help on Composition: Composition: Molecular Weight = 246.04 gm
   Arsenic  60.90 %  As
   Sulfur   39.10 %  S
           100.00 % 
Help on Empirical Formula: Empirical Formula: As2S3
Help on Environment: Environment: Low temperature hydrothermal veins, hot springs, and fumaroles; also commony as an alteration product of arsenic minerals, especially realgar.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1747
Help on Locality: Locality: Common world wide. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Latin, auripigmentum, in allusion to the vivid golden hue.
Help on Name Pronunciation: Name Pronunciation: Orpiment Say ORPIMENT
Help on Synonym: Synonym: ICSD 15239
  PDF 24-75

Orpiment Image

Click Here for Larger   Image in a New Browser Window Images:
Click Here for Larger   Image


Comments: Deep orange-colored orpiment crystal aggregate.
Location: Twin Creeks mine, 62 bench, north of Winnemucca, Humboldt County, Nevada. USA. Scale: 6.5 x 5.5 cm.
© Fabre Minerals

Orpiment Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1.1981:1:0.4431
Help on Cell Dimensions: Cell Dimensions: a = 11.49, b = 9.59, c = 4.25, Z = 4; beta = 90.45° V = 468.29 Den(Calc)= 3.49
Help on Crystal System: Crystal System: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21/n
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 4.82(1), 2.7(0.53), 4(0.47),
Help on Forms: Forms:

Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 0 1 0) ( 1 2 0) ( 1 1 1) ( 1 0 1)

Warning: this java applet does not work in some browsers because of security restrictions.


Physical Properties of Orpiment

Help on Cleavage: Cleavage: {010} Perfect
Help on Color: Color: Lemon yellow, Brownish yellow, Orange yellow.
Help on Density: Density: 3.49 - 3.56, Average = 3.52
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Sectile - Curved shavings or scrapings produced by a knife blade, (e.g. graphite).
Help on Habit: Habit: Foliated - Two dimensional platy forms.
Help on Habit: Habit: Massive - Fibrous - Distinctly fibrous fine-grained forms.
Help on Habit: Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Help on Hardness: Hardness: 1.5-2 - Talc-Gypsum
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Pearly
Help on Streak: Streak: pale yellow

Optical Properties of Orpiment

Help on Optical Data: Optical Data: Biaxial (-), a=2.4, b=2.81, g=3.02, bire=0.6200, 2V(Calc)=62, 2V(Meas)=76. Dispersion r > v strong.
Help on Pleochroism (x): Pleochroism (x): yellow.
Help on Pleochroism (y): Pleochroism (y): yellow.
Help on Pleochroism (z): Pleochroism (z): greenish yellow.
Help on RL Anisotrophism: RL Anisotrophism: Bearly observable because of the strong internal reflections.
Help on RL Pleochroism: RL Pleochroism: Strong, white to gray-white with a reddish tint.
Help on Reflectivity Reflectivity
Standardized Intensity (100%) Reflection Spectra of Orpiment in Air
λ R1 R2  ∑ R1(λ)   ∑ R2(λ) 
 400 nm   29.80   39.90 
 420 nm   27.60   36.80 
 440 nm   25.40   33.70 
 460 nm   23.60   31.20 
 480 nm   22.30   29.50 
 500 nm   21.40   28.40 
 520 nm   20.90   27.70 
 540 nm   20.50   27.20 
 560 nm   20.10   26.70 
 580 nm   19.70   26.40 
 600 nm   19.40   25.90 
 620 nm   19.10   25.60 
 640 nm   19.00   25.40 
 660 nm   18.80   25.20 
 680 nm   18.70   25.10 
 700 nm   18.60   25.00 
Calculated Relative Intensity Colors of Orpiment in Air
   0%   50% 100% 150% 200% 250% 300% 350% 400% 440%

Calculated Properties of Orpiment

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.23 gm/cc
note: Specific Gravity of Orpiment =3.49 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0029323747
Boson Index = 0.9970676253
Help on Photoelectric: Photoelectric: PEOrpiment = 44.66 barns/electron
U=PEOrpiment x rElectron Density= 144.44 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Orpiment is Not Radioactive

Orpiment Classification

Help on  Dana Class: Dana Class: (02)Sulfides - Including Selenides and Tellurides
  (02.11)where Am Bn Xp, with (m+n):p=2:3
  (02.11.01)Orpiment Group Orpiment As2S3 P 21/n 2/m Getchellite AsSbS3 P 21/a 2/m
Help on  Strunz Class: Strunz Class: 02.FA.30 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf
  02.F - Sulfides of Arsenic, Alkalies; Sulfides with Halide, Oxide, Hydroxide, H2O
  02.FA -With As, (Sb), S
02.FA.30 Orpiment As2S3 P 21/n 2/m
02.FA.30 Laphamite As2(Se,S)3 P 21/n 2/m

Other Orpiment Information

Help on References: References: NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1)
Help on See Also: See Also: Links to other databases for Orpiment :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - Philatelic Mineralogy
15 - QUT Mineral Atlas
16 - Ruff.Info
18 - theimage

Search for Orpiment using:

Web webmineral.com
[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Orpiment :

Ask about Orpiment here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Espa´┐Żol

Print or Cut-and-Paste your Orpiment Specimen Label here :


Dana No: Strunz No: 02.FA.30





Dakota Matrix
Excalibur Minerals
Exceptional Minerals
Hudson Insitute
John Betts Fine Minerals
Mc Dougall Minerals
Mineral News
Rock and Mineral Shows
Weinrich Minerals, Inc.