Mineralogy Database

Crookesite Mineral Data

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General Crookesite Information

Help on Chemical  Formula: Chemical Formula: Cu7(Tl,Ag)Se4
Help on Composition: Composition: Molecular Weight = 940.92 gm
   Thallium  16.29 %  Tl
   Copper    47.28 %  Cu
   Silver     2.87 %  Ag
   Selenium  33.57 %  Se
            ______ 
            100.00 % 
Help on Empirical Formula: Empirical Formula: Cu7Tl0.75Ag0.25Se4
Help on Environment: Environment: Of hydrothermal origin, with other selenides.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1866
Help on Locality: Locality: From Skrikerum, near Tryserum, Kalmar, Sweden. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: After Sir William Crookes (1832-1919), who discovered thallium.
Help on Synonym: Synonym: ICSD 69104
  PDF 41-1457
 

Crookesite Image

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

Comments: Polished section (PPL) showing zoned crystal of cream-colored eucairite and pale lavender crookesite along with steel blue umangite and white clausthalite in dark gray gangue..
Location: Mine dump (tailings) of Shaft 371 near Hartenstein/Saxony, Germany. Scale: Picture size 5 mm.
© Thomas Schlothauer

Crookesite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:0.37891
Help on Cell Dimensions: Cell Dimensions: a = 10.435, c = 3.954, Z = 2; V = 430.55 Den(Calc)= 7.26
Help on Crystal System: Crystal System: Tetragonal - Disphenoidal H-M Symbol (4) Space Group: I 4
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.59(1), 3.29(1), 3(0.8),
 

Physical Properties of Crookesite

Help on Cleavage: Cleavage: {???} Good
Help on Color: Color: Blue gray, Brown pink, Gray.
Help on Density: Density: 6.9
Help on Diaphaneity: Diaphaneity: Opaque
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Habit: Habit: Disseminated - Occurs in small, distinct particles dispersed in matrix.
Help on Hardness: Hardness: 2.5-3 - Finger Nail-Calcite
Help on Luster: Luster: Metallic
 

Optical Properties of Crookesite

Help on RL Anisotrophism: RL Anisotrophism: Weak but distinct, in brownish tones.
Help on Reflectivity Reflectivity
Standardized Intensity (100%) Reflection Spectra of Crookesite in Air
λ R1 R2  ∑ R1(λ)   ∑ R2(λ) 
 400 nm   33.00   37.30 
   
 420 nm   32.60   37.40 
 440 nm   32.20   37.50 
 460 nm   31.80   37.40 
 480 nm   31.40   37.30 
 500 nm   31.40   37.00 
 520 nm   31.50   36.70 
 540 nm   31.50   36.50 
 560 nm   31.60   36.50 
 580 nm   31.70   36.60 
 600 nm   31.90   36.80 
 620 nm   32.20   37.00 
 640 nm   32.30   37.40 
 660 nm   32.50   37.80 
 680 nm   32.70   38.20 
 700 nm   32.80   38.60 
Calculated Relative Intensity Colors of Crookesite in Air
Relative
Intensity
   0%   30%   60%   90% 100% 120% 150% 180% 210% 240% 270% 280%
R1                        
R2                        
 

Calculated Properties of Crookesite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=6.35 gm/cc
note: Specific Gravity of Crookesite =7.26 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.02
Boson Index = 0.98
Help on Photoelectric: Photoelectric: PECrookesite = 331.04 barns/electron
U=PECrookesite x rElectron Density=2,102.14 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Crookesite is Not Radioactive
 

Crookesite Classification

Help on  Dana Class: Dana Class: 02.04.12.01 (02)Sulfides - Including Selenides and Tellurides
  (02.04)where Am Bn Xp, with (m+n):p=2:1
  (02.04.12)Dana Group
 
02.04.12.01 Crookesite Cu7(Tl,Ag)Se4 I 4 4
 
02.04.12.02 Sabatierite Cu4TlSe3 P 4/mmm 4/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 02.BD.50 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf
  02.B - Metal Sulfides, M:S > 1:1 (mainly 2:1)
  02.BD -With Hg, Tl
 
02.BD.50 Crookesite Cu7(Tl,Ag)Se4 I 4 4
 

Other Crookesite 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 Crookesite :
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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Print or Cut-and-Paste your Crookesite Specimen Label here :

Crookesite

Cu7(Tl,Ag)Se4
Dana No: 02.04.12.01 Strunz No: 02.BD.50
Locality:

 

Notes:

 

 
   
 


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