Laforêtite
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About Laforêtite
Formula:
AgInS2
Colour:
Brown
Lustre:
Metallic
Hardness:
3
Specific Gravity:
4.93 (Calculated)
Crystal System:
Tetragonal
Member of:
Name:
Named for Claude P. Laforêt (b. 1936), metallographer at the Bureau de Recherches Géologiques et Minières, who first observed the mineral at the Montgros Mine.
Classification of Laforêtite
Approved
Approval year:
1995
2/C.03-45
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.
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.
Physical Properties of Laforêtite
Metallic
Transparency:
Opaque
Colour:
Brown
Streak:
Chocolate brown
Hardness:
3 on Mohs scale
Hardness:
VHN100=183 kg/mm2 - Vickers
Hardness Data:
Estimated
Cleavage:
None Observed
Density:
4.93(1) g/cm3 (Calculated)
Optical Data of Laforêtite
Anisotropism:
Strong, brick red with orange tint to bluish-grey purplish
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). Top of box is 100%. Peak reflectance is 26%.
Colour in reflected light:
Brownish grey
Internal Reflections:
strawberry red
Pleochroism:
Weak
Comments:
Brown to clear brown-grey tints
Chemical Properties of Laforêtite
Formula:
AgInS2
Elements listed:
Common Impurities:
Cu,Fe,Se
Crystallography of Laforêtite
Crystal System:
Tetragonal
Class (H-M):
4 2m - Scalenohedral
Space Group:
I4 2d
Cell Parameters:
a = 5.880(2) Å, c = 11.21(1) Å
Ratio:
a:c = 1 : 1.906
Unit Cell V:
387.57 ų
Z:
4
Twinning:
Polysynthetic lamellar observed in polished sections.
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
3.351 Å | (100) |
2.942 Å | (80) |
2.082 Å | (75) |
2.035 Å | (75) |
1.768 Å | (80) |
1.707 Å | (35) |
1.189 Å | (40) |
Comments:
From synthetic material because of small size of grains.
Type Occurrence of Laforêtite
General Appearance of Type Material:
tiny < 30 μm anhedral inclusions in galena
Place of Conservation of Type Material:
Geological Museum of Lausanne, Switzerland (no. MGL 58600) and fragments of holotype material, with submicroscopic lafortite inclusions, are also deposited at the Galerie de Mineralogie, Museum National d'Histoire Naturelle, Paris, France.
Geological Setting of Type Material:
brecciated vein sample from the mine dump
Associated Minerals at Type Locality:
Synonyms of Laforêtite
Other Language Names for Laforêtite
Relationship of Laforêtite to other Species
Member of:
Other Members of this group:
Chalcopyrite | CuFeS2 | Tet. 4 2m : I4 2d |
Eskebornite | CuFeSe2 | Tet. |
Gallite | CuGaS2 | Tet. 4 2m : I4 2d |
Lenaite | AgFeS2 | Tet. 4 2m : I4 2d |
Roquesite | CuInS2 | Tet. 4 2m : I4 2d |
Shenzhuangite | NiFeS2 | Tet. 4 2m : I4 2d |
Unnamed (Cu-Mn-Sn Sulfide) | Cu2MnSnS4 |
Related Minerals - Nickel-Strunz Grouping
2.CB. | Agmantinite | Ag2MnSnS4 | Orth. |
2.CB.05a | Coloradoite | HgTe | Iso. m3m (4/m 3 2/m) |
2.CB.05a | Hawleyite | CdS | Iso. 4 3m : F4 3m |
2.CB.05a | Metacinnabar | HgS | Iso. 4 3m : F4 3m |
2.CB.05c | Polhemusite | (Zn,Hg)S | Tet. |
2.CB.05b | Sakuraiite | (Cu,Zn,Fe)3(In,Sn)S4 | Iso. |
2.CB.05a | Sphalerite | ZnS | Iso. 4 3m : F4 3m |
2.CB.05a | Stilleite | ZnSe | Iso. 4 3m : F4 3m |
2.CB.05a | Tiemannite | HgSe | Iso. 4 3m : F4 3m |
2.CB.05 | UM1998-15-S:CuFeZn | Cu2Fe3Zn5S10 | |
2.CB.05a | Rudashevskyite | (Fe,Zn)S | Iso. 4 3m : F4 3m |
2.CB.10a | Chalcopyrite | CuFeS2 | Tet. 4 2m : I4 2d |
2.CB.10a | Eskebornite | CuFeSe2 | Tet. |
2.CB.10a | Gallite | CuGaS2 | Tet. 4 2m : I4 2d |
2.CB.10b | Haycockite | Cu4Fe5S8 | Orth. 2 2 2 |
2.CB.10a | Lenaite | AgFeS2 | Tet. 4 2m : I4 2d |
2.CB.10b | Mooihoekite | Cu9Fe9S16 | Tet. |
2.CB.10b | Putoranite | Cu1.1Fe1.2S2 | Iso. |
2.CB.10a | Roquesite | CuInS2 | Tet. 4 2m : I4 2d |
2.CB.10b | Talnakhite | Cu9(Fe,Ni)8S16 | Iso. 4 3m : I4 3m |
2.CB.15a | Černýite | Cu2(Cd,Zn,Fe)SnS4 | Tet. 4 2m : I4 2m |
2.CB.15a | Ferrokësterite | Cu2FeSnS4 | Tet. 4 : I4 |
2.CB.15a | Hocartite | Ag2(Fe2+,Zn)SnS4 | Tet. 4 2m : I4 2m |
2.CB.15a | Idaite | Cu5FeS6 | Hex. |
2.CB.15a | Kësterite | Cu2ZnSnS4 | Tet. 4 : I4 |
2.CB.15a | Kuramite | Cu3SnS4 | Tet. |
2.CB.15b | Mohite | Cu2SnS3 | Mon. |
2.CB.15a | Pirquitasite | Ag2ZnSnS4 | Tet. 4 : I4 |
2.CB.15a | Stannite | Cu2FeSnS4 | Tet. 4 2m : I4 2m |
2.CB.15c | Stannoidite | Cu+6Cu2+2(Fe2+,Zn)3Sn2S12 | Orth. |
2.CB.15a | Velikite | Cu2HgSnS4 | Tet. |
2.CB.15c | UM2006-11-S:CuFeGeZn | Cu8(Fe,Zn)3Ge2S12 (?) | |
2.CB.20 | Chatkalite | Cu6FeSn2S8 | Tet. 4 2m : P4m2 |
2.CB.20 | Mawsonite | Cu6Fe2SnS8 | Tet. 4 2m : P4m2 |
2.CB.30 | Colusite | Cu13VAs3S16 | Iso. 4 3m : P4 3n |
2.CB.30 | Germanite | Cu13Fe2Ge2S16 | Iso. 4 3m : P4 3n |
2.CB.30 | Germanocolusite | Cu26V2(Ge,As)6S32 | Iso. 4 3m : P4 3m |
2.CB.30 | Nekrasovite | Cu26V2(Sn,As,Sb)6S32 | Iso. |
2.CB.30 | Stibiocolusite | Cu13V(Sb,Sn,As)3S16 | Iso. 4 3m : P4 3m |
2.CB.30 | Ovamboite | Cu20(Fe,Cu,Zn)6W2Ge6S32 | Iso. |
2.CB.30 | Maikainite | Cu20(Fe,Cu)6Mo2Ge6S32 | Iso. m3m (4/m 3 2/m) |
2.CB.35a | Hemusite | Cu6SnMoS8 | Iso. |
2.CB.35a | Kiddcreekite | Cu6SnWS8 | Iso. 4 3m : F4 3m |
2.CB.35a | Polkovicite | (Fe,Pb)3(Ge,Fe)1-xS4 | Iso. |
2.CB.35a | Renierite | (Cu1+,Zn)11Fe4(Ge4+,As5+)2S16 | Tet. 4 2m : P4 2c |
2.CB.35a | Vinciennite | Cu+7Cu2+3Fe2+2Fe3+2Sn(As,Sb)S16 | Tet. |
2.CB.35a | Morozeviczite | (Pb,Fe)3Ge1-xS4 | Iso. |
2.CB.35b | Catamarcaite | Cu6GeWS8 | Hex. 6mm : P63mc |
2.CB.40 | Lautite | CuAsS | Orth. mmm (2/m 2/m 2/m) : Pnma |
2.CB.45 | Cadmoselite | CdSe | Hex. 6mm : P63mc |
2.CB.45 | Greenockite | CdS | Hex. 6mm : P63mc |
2.CB.45 | Wurtzite | (Zn,Fe)S | Hex. 6mm : P63mc |
2.CB.45 | Rambergite | MnS | Hex. 6mm : P63mc |
2.CB.45 | Buseckite | (Fe,Zn,Mn)S | Hex. 6mm : P63mc |
2.CB.55a | Cubanite | CuFe2S3 | Orth. mmm (2/m 2/m 2/m) |
2.CB.55b | Isocubanite | CuFe2S3 | Iso. m3m (4/m 3 2/m) : Fm3m |
2.CB.60 | Picotpaulite | TlFe2S3 | Orth. mmm (2/m 2/m 2/m) : Cmcm |
2.CB.60 | Raguinite | TlFeS2 | Orth. |
2.CB.65 | Argentopyrite | AgFe2S3 | Mon. 2/m |
2.CB.65 | Sternbergite | AgFe2S3 | Orth. mmm (2/m 2/m 2/m) |
2.CB.70 | Sulvanite | Cu3VS4 | Iso. 4 3m : P4 3m |
2.CB.75 | Vulcanite | CuTe | Orth. |
2.CB.80 | Empressite | AgTe | Orth. mmm (2/m 2/m 2/m) |
2.CB.85 | Muthmannite | AuAgTe2 | Mon. 2/m : P2/m |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
References for Laforêtite
Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Meisser, N., Thelin, P., Chiappero, P.J., Maurel, C. (1999) Laforêtite, AgInS2, a new mineral of the chalcopyrite group from the Montgros mine, Haute-Loire, France. European Journal of Mineralogy: 11: 891-897.
Jambor, J.L., Kovalenker, V.A., Roberts, A.C. (2000) New mineral names. American Mineralogist: 85: 873-877.
Mandarino, J.A. (2000) Abstracts of new mineral descriptions. Mineralogical Record: 31(4): 363-372.
Internet Links for Laforêtite
mindat.org URL:
https://www.mindat.org/min-7149.html
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Localities for Laforêtite
Locality List




All localities listed without proper references should be considered as questionable.
Egypt | |
| Sallam, O. R., Alshami, A. S., Azab, M. S., & El Akeed, I. A. (2014) The Occurrence of Silver-Gold Mineralization Associated With Uranium Bearing Minerals and Base Metal Sulphide, El Sheikh Soliman Area, South Sinai, Egypt. Egyptian Journal of Pure and Applied Science 52(1):47-54 |
France (TL) | |
| Meisser N. et al (1999) European Journal of Mineralogy 11: 891-897. |
Japan | |
| Ishihara, S., Matsueda, H. (2011) Chemical characteristics of the indium-polymetallic ores from the Toyoha mine, Hokkaido, Japan. Bulletin of the Geological Survey of Japan: 62(3/4): 131-142. |
Montgros Mine, Pinols, Brioude, Haute-Loire, Auvergne-Rhône-Alpes, France