Classification of Laforêtite |
| IMA status: | Approved 1995 |
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| Strunz 8th edition ID: | 2/C.03-45
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| Nickel-Strunz 10th (pending) edition ID: | 2.CB.10a
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.) C : Metal Sulfides, M: S = 1: 1 (and similar) B : With Zn, Fe, Cu, Ag, etc. |
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| mindat.org URL: | http://www.mindat.org/min-7149.html Please feel free to link to this page. |
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Type Occurrence of Laforêtite |
| Type Locality: | Montgros Mine, Pinols, Pinols, Haute-Loire, Auvergne, France |
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| Geological Setting of type material: | brecciated vein sample from the mine dump |
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| Associated Minerals at type locality: | |
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Physical Properties of Laforêtite |
| Lustre: | Metallic |
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| Diaphaneity (Transparency): | Opaque |
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| Colour: | Brown |
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| Streak: | Chocolate brown |
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| Hardness (Mohs): | 3 |
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| Hardness (Vickers): | VHN100=183 kg/mm2 |
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| Hardness Data: | Estimated |
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| Cleavage: | None Observed |
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| Density (calculated): | 4.92 g/cm3 |
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Crystallography of Laforêtite |
| Crystal System: | Tetragonal |
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| Class (H-M): | 4 2m - Scalenohedral |
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| Space Group: | I4 2d |
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| Cell Parameters: | a = 5.88Å, c = 11.21Å
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| Ratio: | a:c = 1 : 1.906 |
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| Unit Cell Volume: | V 387.57 ų |
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| Z: | 4 |
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| Twinning: | Polysynthetic lamellar observed in polished sections. |
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| X-Ray Powder Diffraction: | | d-spacing | | Intensity | | 3.351 | | (100) | | 2.942 | | (80) | | 2.082 | | (75) | | 2.035 | | (75) | | 1.768 | | (80) | | 1.707 | | (35) |
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| Comments: | From synthetic material because of small size of grains. |
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Optical Data of Laforêtite |
| Type: | Anisotropic |
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| Anisotropism: | Strong, brick red with orange tint to bluish-grey purplish |
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| Reflectivity: | | 480nm | R=26% | | 540nm | R=24.6% | | 580nm | R=24.2% | | 660nm | R=25.8% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 26%. |
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| Colour in reflected light: | Brownish grey |
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| Pleochroism: | Weak |
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| Comments: | Brown to clear brown-grey tints |
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Chemical Properties of Laforêtite |
| Formula: | |
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| Essential elements: | Ag, In, S |
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| All elements listed in formula: | Ag, In, S |
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| Analytical Data: | Means of eight sets of electron microprobe data
Cu (0.04)
Ag (37.68)
In (40.22)
Fe (0.02)
Se (0.01)
S (22.42)
Total: 100.39 wt.% |
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| Empirical Formula: | |
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| Common Impurities: | Cu,Fe,Se |
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Relationship of Laforêtite to other Species |
| Member of Group: | |
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Related Minerals - Nickel-Strunz Grouping):
- + | |
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Other Names for Laforêtite |
| Synonyms: | |
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| Other Languages: | |
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Other Information |
| Health Warning: | No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care. |
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References for Laforêtite |
| Reference List: | Meisser, N., Thelin, P., Chiappero, P.J., and Maurel, C. (1999) Laforêtite, AgInS2, a new mineral of the chalcopyrite group from the Montgros mine, Haute-Loire, France. European Journal of Mineralogy (1999): 11: 891-897.
Mineralogical Record: 31: 368.
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Internet Links for Laforêtite |
| Search Engines: |
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| External Links: | Look for Laforêtite on WebmineralLook for Laforêtite on Athena MineralogyLook for Laforêtite on WikipediaLook for Laforêtite on Mineralien AtlasRaman and XRD data at RRUFF projectAmerican Mineralogist Crystal Structure DatabaseSearch for Laforêtite in the Natural History Museum (London) online catalogueLaforêtite details from Handbook of Mineralogy (PDF) |
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Localities for Laforêtite |