Laforetite Mineral Data
General Laforetite Information
Chemical Formula:
AgInS2
Composition:
Molecular Weight = 286.82 gm
Indium 40.03 % In
Silver 37.61 % Ag
Sulfur 22.36 % S
______
100.00 %
Empirical Formula:
AgInS2
Environment:
Breccia vein sample from the mine dumps. Microscopic inclusions in galena.
IMA Status:
Approved IMA 1995 (Dana # Added)
Locality:
The disused Montgros mine (Pinols claim), near the hamlet La Boriette, about 10 km SW of Langeac, Haute-Loire, France. Link to MinDat.org Location Data.
Name Origin:
Named for Claude P. Laforet (1936-) a metallographer at the Bureau de Recherches Geologiques et Minieres, who first observed the mineral from the Montgros mine.
Synonym:
IMA1995-006
Laforetite Crystallography
Axial Ratios:
a:c = 1:1.90646
Cell Dimensions:
a = 5.88, c = 11.21, Z = 4; V = 387.58 Den(Calc)= 4.92
Crystal System:
Tetragonal - Scalenohedral H-M Symbol (4 2m) Space Group: I 4 2d
X Ray Diffraction:
By Intensity(I/Io ): 3.351(1), 2.942(0.8), 1.768(0.8), 2.03(0.75), 2.082(0.75), 1.189(0.4), 1.707(0.35),
Physical Properties of Laforetite
Cleavage:
None
Color:
Brown.
Diaphaneity:
Opaque
Habit:
Inclusions - Generally found as inclusions in other minerals.
Habit:
Microscopic Crystals - Crystals visible only with microscopes.
Hardness:
3 - Calcite
Luster:
Metallic
Streak:
chocolate brown
Optical Properties of Laforetite
RL Anisotrophism:
Strong, brick-red with an orange tint to bluish-gray purplish.
RL Color:
Brownish gray in oil with abundant strawberry red internal reflections.
RL Pleochroism:
Weak, from brown to brown-gray.
Reflectivity
Standardized Intensity (100%) Reflection Spectra of Laforetite in Air
λ
R
∑ R (λ)
480 nm
26.00
540 nm
24.60
580 nm
24.20
640 nm
24.60
Calculated Relative Intensity Colors of Laforetite in Air
Relative Intensity
0%
40%
80%
100%
120%
160%
200%
240%
280%
320%
360%
R
Calculated Properties of Laforetite
Electron Density:
Bulk Density (Electron Density)=4.39 gm/cc note: Specific Gravity of Laforetite =4.92 gm/cc.
Fermion Index:
Fermion Index = 0.0016769739 Boson Index = 0.9983230261
Photoelectric:
PELaforetite = 213.69 barns/electronU=PELaforetite x r Electron Density= 938.38 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Laforetite is Not Radioactive
Laforetite Classification
Dana Class:
02.09.01.06 (02) Sulfides - Including Selenides and Tellurides
(02.09) where Am Bn Xp, with (m+n):p=1:1
(02.09.01) Chalcopyrite Group (Tetragonal: I-42d)
02.09.01.01 Chalcopyrite CuFeS2 I 4 2d 4 2m
02.09.01.02 Eskebornite CuFeSe2 I 4 2d 4 2m
02.09.01.03 Gallite CuGaS2 I 4 2d 4 2m
02.09.01.04 Roquesite CuInS2 I 4 2d 4 2m
02.09.01.05 Lenaite AgFeS2 P 42 mc 4mm
02.09.01.06 Laforetite ! AgInS2 I 4 2d 4 2m
Strunz Class:
02.CB.10a 02 - SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulf
02.C - Metal Sulfides, M:S = 1:1 (and similar)
02.CB -With Zn, Fe, Cu, Ag, Au, etc
02.CB.10a Chalcopyrite CuFeS2 I 4 2d 4 2m
02.CB.10a Eskebornite CuFeSe2 I 4 2d 4 2m
02.CB.10a Gallite CuGaS2 I 4 2d 4 2m
02.CB.10a Laforetite ! AgInS2 I 4 2d 4 2m
02.CB.10a Lenaite AgFeS2 P 42 mc 4mm
02.CB.10a Roquesite CuInS2 I 4 2d 4 2m
Other Laforetite Information
References:
NAME( MinRec, Vol 31, No 4) PHYS. PROP.(MinRec, Vol 31, No 4) OPTIC PROP.(AmMin, v 85, p 875)
See Also:
Links to other databases for Laforetite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - Handbook of Mineralogy (MinSocAm)
7 - Handbook of Mineralogy (UofA)
8 - MinDAT
9 - Mineralienatlas (Deutsch)
10 - Online Mineral Museum
11 - QUT Mineral Atlas
12 - Ruff.Info
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Laforetite
AgInS2
Dana No: 02.09.01.06 Strunz No: 02.CB.10a
Locality:
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