Mineralogy Database

Lafossaite Mineral Data

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General Lafossaite Information

Help on Chemical  Formula: Chemical Formula: Tl(Cl,Br)
Help on Composition: Composition: Molecular Weight = 252.93 gm
   Thallium  82.99 %  Tl   86.24 % Tl2O
   Bromine    6.07 %  Br    6.07 % Br
               -   %   Br   -0.61 % -O=Br2   
   Chlorine  10.95 %  Cl   10.95 % Cl
               -   %   Cl   -2.47 % -O=Cl2   
            ______        ______ 
            100.00 %      100.17 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Tl1.02Cl0.78Br0.19
Help on Environment: Environment: Occurs as a drusy coating on one surface of a single specimen collected from an active fumarole. Sal ammoniac group.
Help on IMA Status: IMA Status: Approved IMA 2003 (Dana # Added)
Help on Locality: Locality: La Fossa crater, Vulcano, Italy Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the locality.

Lafossaite Crystallography

Help on Cell Dimensions: Cell Dimensions: a = 3.8756, Z = 1; V = 58.21 Den(Calc)= 7.21
Help on Crystal System: Crystal System: Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: P m3m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.745(1)(110 ), 3.887(0.8)(100 ), 1.583(0.7)(211 ),2.237(0.55)(111 ), 1.937(0.5)(200 ), 1.733(0.45)(210 ), 1.226(0.25)(310 ), 1.37(0.25)(220 ), 1.291(0.2)(221,300),

Physical Properties of Lafossaite

Help on Cleavage: Cleavage: None
Help on Color: Color: Grayish brown.
Help on Diaphaneity: Diaphaneity: Translucent
Help on Fracture: Fracture: Malleable - Deforms rather than breaking apart with a hammer.
Help on Habit: Habit: Cubic Crystals - Occurs as cubic shaped crystals.
Help on Habit: Habit: Subhedral Crystals - Occurs as crystals which tend to exhibit a recognizable crystal shape.
Help on Hardness: Hardness: 3-4 - Calcite-Fluorite
Help on Luster: Luster: Resinous - Greasy
Help on Streak: Streak: resinous off white

Optical Properties of Lafossaite

Help on Gladstone-Dale: Gladstone-Dale: CI calc= -0.193 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1753,KC= 0.1469
Ncalc = 2.06
Help on Optical Data: Optical Data: Isotropic, n=2.264.
Help on RL Anisotrophism: RL Anisotrophism: None.
Help on RL Bireflectance: RL Bireflectance: None.
Help on RL Color: RL Color: White with white internal reflections.
Help on RL Pleochroism: RL Pleochroism: None.
Help on Reflectivity Reflectivity
Standardized Intensity (100%) Reflection Spectra of Lafossaite in Air
λ R  ∑ R(λ) 
 470 nm   16.00   
 546 nm   15.20 
 589 nm   15.00 
 650 nm   14.70 
Calculated Relative Intensity Colors of Lafossaite in Air
   0%   60% 100% 120% 180% 240% 300% 360% 420% 480% 540% 590%

Calculated Properties of Lafossaite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=5.88 gm/cc
note: Specific Gravity of Lafossaite =7.21 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0
Boson Index = 1
Help on Photoelectric: Photoelectric: PELafossaite =1,502.75 barns/electron
U=PELafossaite x rElectron Density=8,840.18 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Lafossaite is Not Radioactive

Lafossaite Classification

Help on  Dana Class: Dana Class: (09)Anhydrous and Hydrated Halides
  (09.01)where A X
  (09.01.03)Dana Group Salammoniac NH4Cl P m3m 4/m 3 2/m Lafossaite! Tl(Cl,Br) P m3m 4/m 3 2/m
Help on  Strunz Class: Strunz Class: 03.AA.25 03 - HALIDES
  03.A - Simple Halides, Without H2O
  03.AA -M:X = 1:1, 2:3, 3:5, etc.
03.AA.25 Salammoniac NH4Cl P m3m 4/m 3 2/m
03.AA.25 Lafossaite! Tl(Cl,Br) P m3m 4/m 3 2/m

Other Lafossaite Information

Help on References: References: NAME( AmMin, v91, p1455) PHYS. PROP.(AmMin, v91, p1455) OPTIC PROP.(AmMin, v91, p1455)
Help on See Also: See Also: Links to other databases for Lafossaite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Dana No: Strunz No: 03.AA.25





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