Mineralogy Database

Laphamite Mineral Data

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General Laphamite Information

Help on Chemical  Formula: Chemical Formula: As2(Se,S)3
Help on Composition: Composition: Molecular Weight = 351.55 gm
   Arsenic   42.62 %  As
   Selenium  50.54 %  Se
   Sulfur     6.84 %  S
            100.00 % 
Help on Empirical Formula: Empirical Formula: As2Se2.25S0.75
Help on Environment: Environment: Secondary mineral formed as a sublimation product of a burning anthracite coal mine waste dump fire.
Help on IMA Status: IMA Status: Approved IMA 1986
Help on Locality: Locality: Burnside, Northumberland County, Pennsylvania, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Davis M. Lapham (1931-1974), former Chief Mineralogist of the Pennsylvania Geological Survey.
Help on Name Pronunciation: Name Pronunciation: Laphamite + Pronunciation Say LAPHAMITE
Help on Synonym: Synonym: ICSD 29535
  PDF 26-123

Laphamite Image

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Comments: Brown grain of laphamite.
Location: Northumberland County, Pennsylvania, USA. Scale: Grain size 1.5 mm.
© Thomas Witzke / Abraxas-Verlag

Laphamite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1.2156:1:0.4371
Help on Cell Dimensions: Cell Dimensions: a = 11.86, b = 9.756, c = 4.265, Z = 4; beta = 90.17° V = 493.48 Den(Calc)= 4.73
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): 2.833(1), 2.773(0.8), 4.87(0.7),

Physical Properties of Laphamite

Help on Cleavage: Cleavage: {010} Perfect
Help on Color: Color: Dark red.
Help on Density: Density: 4.5
Help on Diaphaneity: Diaphaneity: Translucent to Subopaque
Help on Fracture: Fracture: Flexible - Flexible fragments.
Help on Habit: Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Help on Hardness: Hardness: 1-2 - Between Talc and Gypsum
Help on Luster: Luster: Resinous
Help on Streak: Streak: red orange

Optical Properties of Laphamite

Help on RL Anisotrophism: RL Anisotrophism: Moderate, in tints of gray.
Help on RL Color: RL Color: Gray-white, strong fiery red internal reflections, golden yellow near scratches.
Help on RL Pleochroism: RL Pleochroism: Moderate, from white to gray.
Help on Reflectivity Reflectivity
Standardized Intensity (100%) Reflection Spectra of Laphamite in Air
λ R1 R2  ∑ R1(λ)   ∑ R2(λ) 
 400 nm   34.40   42.10 
 420 nm   33.90   41.00 
 440 nm   33.80   39.90 
 460 nm   33.80   38.80 
 480 nm   33.20   37.40 
 500 nm   32.30   36.30 
 520 nm   30.90   35.10 
 540 nm   29.50   34.00 
 560 nm   28.40   33.10 
 580 nm   27.60   32.30 
 600 nm   26.90   31.60 
 620 nm   26.40   31.10 
 640 nm   26.40   30.90 
 660 nm   26.30   30.60 
 680 nm   26.10   30.40 
 700 nm   25.90   30.10 
Calculated Relative Intensity Colors of Laphamite in Air
   0%   40%   80% 100% 120% 160% 200% 240% 280% 320%

Calculated Properties of Laphamite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=4.16 gm/cc
note: Specific Gravity of Laphamite =4.73 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.03
Boson Index = 0.97
Help on Photoelectric: Photoelectric: PELaphamite = 72.06 barns/electron
U=PELaphamite x rElectron Density= 299.59 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Laphamite is Not Radioactive

Laphamite 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
  (02.11.06)Dana Group Laphamite As2(Se,S)3 P 21/n 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 Laphamite 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 Laphamite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Dana No: Strunz No: 02.FA.30





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