Larosite
A valid IMA mineral species
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Alfred Larose
Formula:
(Cu,Ag)21PbBiS13
Colour:
Pale buff (polished section)
Lustre:
Metallic
Hardness:
3 - 3½
Specific Gravity:
6.19 (Calculated)
Crystal System:
Orthorhombic
Name:
Named after Alfred LaRose (1870-1940), blacksmith and prospector who was one of the principal discoverers in 1903 of the rich silver deposits of the Cobalt area of northern Ontario, which led to a huge exploration and mining boom in the region. Two versions of the name are found in the literature, LaRose and Larose, the latter traditionally used by the family, but the former used in the naming of the mine. LaRose was inducted into the Canadian Mining Hall of Fame in 2003.
Note: Electron microbe analyses of larosite from Norway (Cook et al., 2010) gave Cu20.47Ag3.68Fe0.22Pb1.01Bi1.06S15.00 calculated on the basis of 15 S atoms.
Unique Identifiers
Mindat ID:
2334
Long-form identifier:
mindat:1:1:2334:0
Similar Names
| Jarosite | A valid IMA mineral species - grandfathered | KFe33+(SO4)2(OH)6 |
| Lacosite | A rock subtype | |
| Lamosite | A synonym of 'Lamalginite' | |
| Larisaite | A valid IMA mineral species | Na(H3O)(UO2)3(SeO3)O2 · 4H2O |
| Marosite (of Cook and Sherwood) | A rock subtype | |
| Marosite (of Iddings) | A rock subtype |
IMA Classification of Larosite
Approved
IMA Formula:
(Cu1+,Ag1+)21Pb2+Bi3+S2-13
Approval year:
1971
First published:
1972
Type description reference:
Classification of Larosite
2.LB.35
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
L : Unclassified Sulfosalts
B : With essential Pb
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
L : Unclassified Sulfosalts
B : With essential Pb
2.16.9.1
2 : SULFIDES
16 : Miscellaneous
2 : SULFIDES
16 : Miscellaneous
5.7.43
5 : Sulphosalts - Sulpharsenites and Sulphobismuthites (those containing Sn, Ge,or V are in Section 6)
7 : Sulpharsenites etc. of Pb and other metals
5 : Sulphosalts - Sulpharsenites and Sulphobismuthites (those containing Sn, Ge,or V are in Section 6)
7 : Sulpharsenites etc. of Pb and other metals
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Lar | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Larosite
Metallic
Transparency:
Opaque
Colour:
Pale buff (polished section)
Hardness:
3 - 3½ on Mohs scale
Hardness:
VHN100=121 - 130 kg/mm2 - Vickers
Density:
6.19 g/cm3 (Calculated)
Optical Data of Larosite
Anisotropism:
Moderate, in gray and greenish buff.
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 400nm | 35.4% | 36.9% |
| 420nm | 34.9% | 36.1% |
| 440nm | 34.4% | 35.4% |
| 460nm | 33.8% | 34.8% |
| 480nm | 33.2% | 33.9% |
| 500nm | 32.7% | 33.3% |
| 520nm | 32.2% | 32.8% |
| 540nm | 32.0% | 32.7% |
| 560nm | 31.9% | 32.6% |
| 580nm | 31.9% | 32.6% |
| 600nm | 31.8% | 32.5% |
| 620nm | 31.9% | 32.5% |
| 640nm | 32.0% | 32.3% |
| 660nm | 32.2% | 32.2% |
| 680nm | 32.3% | 32.0% |
| 700nm | 32.5% | 31.9% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 36.9%.
R1 shown in black, R2 shown in red
Colour in reflected light:
Pale buff
Pleochroism:
Weak
Chemistry of Larosite
Mindat Formula:
(Cu,Ag)21PbBiS13
Element Weights:
Crystallography of Larosite
Crystal System:
Orthorhombic
Cell Parameters:
a = 22.15 Å, b = 24.03 Å, c = 11.67 Å
Ratio:
a:b:c = 0.922 : 1 : 0.486
Unit Cell V:
6,211.53 ų (Calculated from Unit Cell)
Z:
10
Morphology:
small acicular to flamelike crystals, the largest being about 300 µm long.
Comment:
Point Group: n.d.; Space Group: n.d.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.206 Å | (50) |
| 2.917 Å | (90) |
| 2.846 Å | (60) |
| 2.471 Å | (60) |
| 2.555 Å | (40) |
| 2.162 Å | (40) |
| 1.982 Å | (100) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) |
Type Occurrence of Larosite
General Appearance of Type Material:
Acicular to flame-like crystals, up to 25x300 microns, in an assemblage of chalcocite and stromeyerite in the central portion of a layered vein.
Place of Conservation of Type Material:
Canadian Geological Survey, Ottawa, Canada, 12126.
Associated Minerals at Type Locality:
Synonyms of Larosite
Other Language Names for Larosite
Related Minerals - Strunz-mindat Grouping
| 2.LB. | Ciriottiite | Cu(Cu,Ag)3Pb19(Sb,As)22(As2)S56 |
| 2.LB. | Hayyanite | Cu5Ag11Pb76Sb71As17(As2+)8S224 |
| 2.LB. | Wenqingite | Pb5(AsS3)2(Ge2S6) |
| 2.LB.05 | Miharaite | Cu4FePbBiS6 |
| 2.LB.30 | Launayite | Cu2Pb20(Sb,As)26S60 |
| 2.LB.30 | Ardaite | Pb19Sb13S35Cl7 |
| 2.LB.30 | Sorbyite | CuPb9(Sb,As)11S26 |
| 2.LB.30 | Playfairite | Pb16(Sb,As)19S44Cl |
| 2.LB.30 | Sterryite | Cu(Ag,Cu)3Pb19(Sb,As)22(As2)S56 |
| 2.LB.30 | Madocite | Pb19(Sb,As)16S43 |
| 2.LB.40 | Mazzettiite | Ag3HgPbSbTe5 |
| 2.LB.40 | Petrovicite | Cu3HgPbBiSe5 |
| 2.LB.45 | Crerarite | Pt2-x(Bi,Pb)11(S,Se)11 |
| 2.LB.50 | Quijarroite | Cu6HgPb2Bi4Se12 |
| 2.LB.55 | Znamenskyite | Pb4In2Bi4S13 |
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.
Internet Links for Larosite
mindat.org URL:
https://www.mindat.org/min-2334.html
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References for Larosite
Localities for Larosite
Showing 9 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Brazil | |
| Lopes et al. (2024) |
Canada | |
| 159-161. +1 other reference |
| PETRUK (1972) |
China | |
| Binghui Chen et al. (1994) |
| Shihua Li and Jinzhong Qi (2000) +1 other reference |
| Li et al. (2019) |
Norway | |
| Cook et al. (2010) |
| Cook et al. (2010) | |
USA | |
| Gammons et al. (2016) |
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