| |
 |
Lafossaite Mineral Data
|
|
|
General Lafossaite Information
|
 Chemical Formula: |
Tl(Cl,Br) |
| Composition: |
Molecular Weight = 252.93 gm |
| |
Thallium 82.99 % Tl 86.24 % Tl2O |
| |
Bromine 6.07 % Br 6.07 % Br |
| |
- %
Br -0.61 % -O=Br2 |
| |
Chlorine 10.95 % Cl 10.95 % Cl |
| |
- %
Cl -2.47 % -O=Cl2 |
| |
______ ______ |
| |
100.00 % 100.17 % = TOTAL OXIDE |
| Empirical Formula: |
Tl1.02Cl0.78Br0.19 |
| Environment: |
Occurs as a drusy coating on one surface of a single specimen collected from an active fumarole. Sal ammoniac group. |
| IMA Status: |
Approved IMA 2003 (Dana # Added) |
| Locality: |
La Fossa crater, Vulcano, Italy Link to MinDat.org Location Data. |
| Name Origin: |
Named for the locality. |
| |
Lafossaite Crystallography
|
| Cell Dimensions: |
a = 3.8756, Z = 1; V = 58.21 Den(Calc)= 7.21 |
| Crystal System: |
Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: P m3m |
| X Ray Diffraction: |
By Intensity(I/Io): 2.745(1)(110 ), 3.887(0.8)(100 ), 1.583(0.7)(211 ),2.237(0.55)(111 ), 1.937(0.5)(200 ), 1.733(0.45)(210 ), 1.226(0.25)(310 ), 1.37(0.25)(220 ), 1.291(0.2)(221,300), |
| |
Physical Properties of Lafossaite
|
| Cleavage: |
None |
| Color: |
Grayish brown. |
| Diaphaneity: |
Translucent |
| Fracture: |
Malleable - Deforms rather than breaking apart with a hammer. |
| Habit: |
Cubic Crystals - Occurs as cubic shaped crystals. |
| Habit: |
Subhedral Crystals - Occurs as crystals which tend to exhibit a recognizable crystal shape. |
| Hardness: |
3-4 - Calcite-Fluorite |
| Luster: |
Resinous - Greasy |
| Streak: |
resinous off white |
| |
Optical Properties of Lafossaite
|
| Gladstone-Dale: |
CI calc= -0.193 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1753,KC= 0.1469
Ncalc = 2.06 |
| Optical Data: |
Isotropic, n=2.264. |
| RL Anisotrophism: |
None. |
| RL Bireflectance: |
None. |
| RL Color: |
White with white internal reflections. |
| RL Pleochroism: |
None. |
| Reflectivity |
Standardized Intensity (100%) Reflection Spectra of Lafossaite in Air
| λ |
R |
 |
∑ R(λ) |
| 470 nm |
16.00 |
 |
|
| 546 nm |
15.20 |
 |
| 589 nm |
15.00 |
 |
| 650 nm |
14.70 |
 |
Calculated Relative Intensity Colors of Lafossaite in Air
Relative
Intensity |
0% |
60% |
100% |
120% |
180% |
240% |
300% |
360% |
420% |
480% |
540% |
590% |
| R |
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
Calculated Properties of Lafossaite
|
| Electron Density: |
Bulk Density (Electron Density)=5.88 gm/cc
note: Specific Gravity of Lafossaite =7.21 gm/cc.
|
| Fermion Index: |
Fermion Index = 0
Boson Index = 1 |
| Photoelectric: |
PELafossaite =1,502.75 barns/electron
U=PELafossaite x rElectron Density=8,840.18 barns/cc.
|
| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Lafossaite is Not Radioactive |
| |
Lafossaite Classification
|
| Dana Class: |
09.01.03.02 (09)Anhydrous and Hydrated Halides |
| |
(09.01)where A X |
| |
(09.01.03)Dana Group |
| |
09.01.03.01 Salammoniac NH4Cl P m3m 4/m 3 2/m |
| |
09.01.03.02 Lafossaite! Tl(Cl,Br) P m3m 4/m 3 2/m |
| Strunz Class: |
03.AA.25 03 - HALIDES |
| |
03.A - Simple Halides, Without H2O |
| |
03.AA -M:X = 1:1, 2:3, 3:5, etc. |
| |
03.AA.25 Salammoniac NH4Cl P m3m 4/m 3 2/m |
| |
03.AA.25 Lafossaite! Tl(Cl,Br) P m3m 4/m 3 2/m |
| |
Other Lafossaite Information
|
| References: |
NAME( AmMin, v91, p1455) PHYS. PROP.(AmMin, v91, p1455) OPTIC PROP.(AmMin, v91, p1455) |
| See Also: |
Links to other databases for Lafossaite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info
Search for Lafossaite using:
[AOL]
[Bing]
[Dog Pile]
[GeoScienceWorld]
[HotBot]
[Ixquick]
[Lycos]
[MAMMA]
[Scirus]
[Teoma]
[WebCrawler]
[Wikipedia]
[YAHOO]
Visit our Advertisers for Lafossaite :
Ask about Lafossaite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in
Espaņol
Print or Cut-and-Paste your Lafossaite Specimen Label here :
|
Lafossaite
Tl(Cl,Br)
Dana No: 09.01.03.02 Strunz No: 03.AA.25
Locality:
Notes:
|
|
| |
| |
|
| |
Dakota Matrix
Excalibur Minerals
Exceptional Minerals
Hudson Insitute
John Betts Fine Minerals
Mc Dougall Minerals
Mineral News
Rock and Mineral Shows
Weinrich Minerals, Inc.