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Crookesite Mineral Data
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General Crookesite Information
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 Chemical Formula: |
Cu7(Tl,Ag)Se4 |
| Composition: |
Molecular Weight = 940.92 gm |
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Thallium 16.29 % Tl |
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Copper 47.28 % Cu |
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Silver 2.87 % Ag |
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Selenium 33.57 % Se |
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______ |
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100.00 % |
| Empirical Formula: |
Cu7Tl0.75Ag0.25Se4 |
| Environment: |
Of hydrothermal origin, with other selenides. |
| IMA Status: |
Valid Species (Pre-IMA) 1866 |
| Locality: |
From Skrikerum, near Tryserum, Kalmar, Sweden. Link to MinDat.org Location Data. |
| Name Origin: |
After Sir William Crookes (1832-1919), who discovered thallium. |
| Synonym: |
ICSD 69104 |
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PDF 41-1457 |
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Crookesite Image |
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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 |
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Crookesite Crystallography
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| Axial Ratios: |
a:c = 1:0.37891 |
| Cell Dimensions: |
a = 10.435, c = 3.954, Z = 2; V = 430.55 Den(Calc)= 7.26 |
| Crystal System: |
Tetragonal - Disphenoidal H-M Symbol (4) Space Group: I 4 |
| X Ray Diffraction: |
By Intensity(I/Io): 2.59(1), 3.29(1), 3(0.8), |
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Physical Properties of Crookesite
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| Cleavage: |
{???} Good |
| Color: |
Blue gray, Brown pink, Gray. |
| Density: |
6.9 |
| Diaphaneity: |
Opaque |
| Fracture: |
Brittle - Generally displayed by glasses and most non-metallic minerals. |
| Habit: |
Disseminated - Occurs in small, distinct particles dispersed in matrix. |
| Hardness: |
2.5-3 - Finger Nail-Calcite |
| Luster: |
Metallic |
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Optical Properties of Crookesite
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| RL Anisotrophism: |
Weak but distinct, in brownish tones. |
| Reflectivity |
Standardized Intensity (100%) Reflection Spectra of Crookesite in Air
| λ |
R1 |
R2 |
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∑ R1(λ) |
∑ R2(λ) |
| 400 nm |
33.00 |
37.30 |
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| 420 nm |
32.60 |
37.40 |
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| 440 nm |
32.20 |
37.50 |
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| 460 nm |
31.80 |
37.40 |
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| 480 nm |
31.40 |
37.30 |
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| 500 nm |
31.40 |
37.00 |
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| 520 nm |
31.50 |
36.70 |
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| 540 nm |
31.50 |
36.50 |
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| 560 nm |
31.60 |
36.50 |
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| 580 nm |
31.70 |
36.60 |
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| 600 nm |
31.90 |
36.80 |
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| 620 nm |
32.20 |
37.00 |
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| 640 nm |
32.30 |
37.40 |
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| 660 nm |
32.50 |
37.80 |
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| 680 nm |
32.70 |
38.20 |
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| 700 nm |
32.80 |
38.60 |
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Calculated Relative Intensity Colors of Crookesite in Air
Relative
Intensity |
0% |
30% |
60% |
90% |
100% |
120% |
150% |
180% |
210% |
240% |
270% |
280% |
| R1 |
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| R2 |
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Calculated Properties of Crookesite
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| Electron Density: |
Bulk Density (Electron Density)=6.35 gm/cc
note: Specific Gravity of Crookesite =7.26 gm/cc.
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| Fermion Index: |
Fermion Index = 0.02
Boson Index = 0.98 |
| Photoelectric: |
PECrookesite = 331.04 barns/electron
U=PECrookesite x rElectron Density=2,102.14 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Crookesite is Not Radioactive |
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Crookesite Classification
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| Dana Class: |
02.04.12.01 (02)Sulfides - Including Selenides and Tellurides |
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(02.04)where Am Bn Xp, with (m+n):p=2:1 |
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(02.04.12)Dana Group |
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02.04.12.01 Crookesite Cu7(Tl,Ag)Se4 I 4 4 |
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02.04.12.02 Sabatierite Cu4TlSe3 P 4/mmm 4/m 2/m 2/m |
| Strunz Class: |
02.BD.50 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf |
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02.B - Metal Sulfides, M:S > 1:1 (mainly 2:1) |
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02.BD -With Hg, Tl |
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02.BD.50 Crookesite Cu7(Tl,Ag)Se4 I 4 4 |
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Other Crookesite Information
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| References: |
NAME( AntBidBlaNic1) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic1) |
| 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 :
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Crookesite
Cu7(Tl,Ag)Se4
Dana No: 02.04.12.01 Strunz No: 02.BD.50
Locality:
Notes:
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