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Geffroyite Mineral Data
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General Geffroyite Information
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 Chemical Formula: |
(Ag,Cu,Fe)9(Se,S)8 |
| Composition: |
Molecular Weight = 1,342.22 gm |
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Iron 3.74 % Fe |
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Copper 12.78 % Cu |
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Silver 43.40 % Ag |
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Selenium 35.30 % Se |
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Sulfur 4.78 % S |
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______ |
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100.00 % |
| Empirical Formula: |
Ag5.4Cu2.7Fe2+0.9Se6S2 |
| Environment: |
As late stage deposits in veins cutting granite. Micro-myrmikitic texture intergrowth with clausthalite and eskebornite. |
| IMA Status: |
Approved IMA 1982 |
| Locality: |
From Chameane, Puy-de-Dome, France. Link to MinDat.org Location Data. |
| Name Origin: |
To honor Jaques Geffroy, metallugist for the French Atomic Energy Commission. |
| Name Pronunciation: |
Geffroyite + Pronunciation  |
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Geffroyite Image |
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Images:
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Geffroyite
Comments: Silvery-gray grains of geffroyite to <0.5mm embedded in tan barite matrix.
Location: Moctezuma mine, Moctezuma, Sonora, Mexcio.
Scale: Overall: 3 x 2 x 2 cm.
© Tom Loomis / Dakota Matrix |
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Geffroyite Crystallography
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| Cell Dimensions: |
a = 10.889, Z = 3; V = 1,291.11 Den(Calc)= 5.18 |
| Crystal System: |
Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F m3m |
| X Ray Diffraction: |
By Intensity(I/Io): 1.925(1), 3.145(0.9), 3.282(0.9), |
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Physical Properties of Geffroyite
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| Color: |
Bronze brown. |
| Density: |
5.39 |
| Diaphaneity: |
Opaque |
| Hardness: |
2.5 - Finger Nail |
| Luster: |
Metallic |
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Optical Properties of Geffroyite
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| RL Color: |
Brown with a creamy tint. |
| Reflectivity |
Standardized Intensity (100%) Reflection Spectra of Geffroyite in Air
| λ |
R |
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∑ R(λ) |
| 420 nm |
19.00 |
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| 440 nm |
21.40 |
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| 460 nm |
23.50 |
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| 480 nm |
25.50 |
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| 500 nm |
27.50 |
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| 520 nm |
29.10 |
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| 540 nm |
30.10 |
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| 560 nm |
31.70 |
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| 580 nm |
32.70 |
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| 600 nm |
33.60 |
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| 620 nm |
34.40 |
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| 640 nm |
35.10 |
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| 660 nm |
35.80 |
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| 680 nm |
36.30 |
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| 700 nm |
36.90 |
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Calculated Relative Intensity Colors of Geffroyite in Air
Relative
Intensity |
0% |
40% |
80% |
100% |
120% |
160% |
200% |
240% |
280% |
320% |
360% |
390% |
| R |
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Calculated Properties of Geffroyite
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| Electron Density: |
Bulk Density (Electron Density)=4.57 gm/cc
note: Specific Gravity of Geffroyite =5.18 gm/cc.
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| Fermion Index: |
Fermion Index = 0.02
Boson Index = 0.98 |
| Photoelectric: |
PEGeffroyite = 147.93 barns/electron
U=PEGeffroyite x rElectron Density= 675.39 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Geffroyite is Not Radioactive |
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Geffroyite Classification
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| Dana Class: |
02.07.01.06 (02)Sulfides - Including Selenides and Tellurides |
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(02.07)where Am Bn Xp, with (m+n):p=9:8 |
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(02.07.01)Pentalndite Group (Isometric: Fm3m) |
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02.07.01.01 Pentlandite (Fe,Ni)9S8 F m3m 4/m 3 2/m |
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02.07.01.02 Argentopentlandite Ag(Fe,Ni)8S8 F m3m 4/m 3 2/m |
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02.07.01.03 Cobaltpentlandite Co9S8 F m3m 4/m 3 2/m |
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02.07.01.04 Shadlunite (Pb,Cd)(Fe,Cu)8S8 F m3m 4/m 3 2/m |
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02.07.01.05 Manganoshadlunite (Mn,Pb)(Cu,Fe)8S8 F m3m 4/m 3 2/m |
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02.07.01.06 Geffroyite (Ag,Cu,Fe)9(Se,S)8 F m3m 4/m 3 2/m |
| Strunz Class: |
02.BB.15a 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.BB -With Ni, Fe |
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02.BB.15a Argentopentlandite Ag(Fe,Ni)8S8 F m3m 4/m 3 2/m |
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02.BB.15a Cobaltpentlandite Co9S8 F m3m 4/m 3 2/m |
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02.BB.15a Geffroyite (Ag,Cu,Fe)9(Se,S)8 F m3m 4/m 3 2/m |
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02.BB.15a Manganoshadlunite (Mn,Pb)(Cu,Fe)8S8 F m3m 4/m 3 2/m |
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02.BB.15a Pentlandite (Fe,Ni)9S8 F m3m 4/m 3 2/m |
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02.BB.15a Shadlunite (Pb,Cd)(Fe,Cu)8S8 F m3m 4/m 3 2/m |
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Other Geffroyite 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 Geffroyite :
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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Geffroyite
(Ag,Cu,Fe)9(Se,S)8
Dana No: 02.07.01.06 Strunz No: 02.BB.15a
Locality:
Notes:
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