Edgarite
A valid IMA mineral species
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About Edgarite
Formula:
FeNb3S6
FeNb3+2Nb4+S6
Colour:
Dark grey
Lustre:
Metallic
Hardness:
2 - 2½
Specific Gravity:
4.99 (Calculated)
Crystal System:
Hexagonal
Name:
Named after Alan D. Edgar (1935–1998), Professor of Petrology, University of Western Ontario, London, Ontario, Canada, in recognition of his contributions to the study of alkaline rocks and synthetic equivalents.
Type Locality:
An unusual sulphide mineral that appears to have formed at a very late, or final, stage of metamorphism, after the main event of fenitization, from a highly reduced, subalkaline S-C-H-rich fluid, which may have remobilized Nb as a result of destabilization of oxide minerals (Barkov et al. 2000).
The first mineral showing chalcophile behaviour of Nb. Also the first mineral with two reduced Nb cations (compare niobocarbide).
The first mineral showing chalcophile behaviour of Nb. Also the first mineral with two reduced Nb cations (compare niobocarbide).
Unique Identifiers
Mindat ID:
6910
Long-form identifier:
mindat:1:1:6910:2
IMA Classification of Edgarite
Approved
IMA Formula:
Fe3+Nb3+3S2-6
Approval year:
1995
First published:
2000
Type description reference:
Barkov, A. Y., Martin, R. F., Men'shikov, Y. P., Savchenko, Y. E., Thibault, Y., Laajoki, K. V. O. (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence for chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology, 138 (3) 229-236 doi:10.1007/s004100050559
Classification of Edgarite
2.DB.25
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
D : Metal Sulfides, M: S = 3 :4 and 2:3
B : M:S = 2:3
2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
D : Metal Sulfides, M: S = 3 :4 and 2:3
B : M:S = 2:3
Dana 7th ed.:
2.11.13.1
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 |
|---|---|---|
| Edg | 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 Edgarite
Metallic
Transparency:
Opaque
Colour:
Dark grey
Hardness:
2 - 2½ on Mohs scale
Hardness:
VHN100=135 (5 s test time) - Vickers
Cleavage:
Perfect
basal
basal
Density:
4.99 g/cm3 (Calculated)
Optical Data of Edgarite
Anisotropism:
White to dark brown
Reflectivity:
| Wavelength | R1 (%) | R2 (%) |
|---|---|---|
| 470nm | 28.1% | 40.2% |
| 546nm | 27.4% | 39.3% |
| 589nm | 27.0% | 38.5% |
| 650nm | 27.0% | 36.9% |
Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 40.2%.
R1 shown in black, R2 shown in red
Pleochroism:
Strong
Comments:
Grey to light grey with a bluish tint
Comments:
Anisotropy strong.
Chemistry of Edgarite
Mindat Formula:
FeNb3S6
FeNb3+2Nb4+S6
FeNb3+2Nb4+S6
Element Weights:
Elements listed:
Common Impurities:
V,Mn
Crystallography of Edgarite
Crystal System:
Hexagonal
Class (H-M):
6 - Pyramidal
Space Group:
P63
Cell Parameters:
a = 5.912(1) Å, c = 12.675(2) Å
Ratio:
a:c = 1 : 2.144
Unit Cell V:
383.7 ų
Z:
2
Comment:
From Bindi and Martin (2018)
Crystal Structure
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2x2x2 | 3x3x3 | 4x4x4
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0013199 | Edgarite | Anzenhofer K, van den Berg J M, Cossee P, Helle J N (1970) The crystal structures and magnetic susceptibilities of MnNb3S6, FeNb3S6, CoNb3S6 and NiNb3S6 Journal of Physics and Chemistry of Solids 31 1057-1067 | 1970 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.11 Å | (80) |
| 2.606 Å | (80) |
| 2.096 Å | (100) |
| 1.665 Å | (80) |
Reference:
Barkov, A. Y., Martin, R. F., Men'shikov, Y. P., Savchenko, Y. E., Thibault, Y., Laajoki, K. V. O. (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence for chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology, 138 (3) 229-236 doi:10.1007/s004100050559
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]) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Edgarite
General Appearance of Type Material:
Platy inclusions in Ti-(V)-rich pyrrhotite and ferroan alabandite, and as dark gray aggregates of platy grains.
Place of Conservation of Type Material:
Royal Ontario Museum, Toronto, Canada.
Geological Setting of Type Material:
In a feldspar-rich fenitized xenolith approximately 200m across in foyaite at the Khibina alkaline complex.
Associated Minerals at Type Locality:
Reference:
Barkov, A. Y., Martin, R. F., Men'shikov, Y. P., Savchenko, Y. E., Thibault, Y., Laajoki, K. V. O. (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence for chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology, 138 (3) 229-236 doi:10.1007/s004100050559
Synonyms of Edgarite
Other Language Names for Edgarite
Common Associates
Associations Based on Photo Data:
| 3 photos of Edgarite associated with Pyrrhotite | Fe1-xS |
Related Minerals - Strunz-mindat Grouping
| 2.DB. | Stangersite | SnGeS3 |
| 2.DB.05 | Antimonselite | Sb2Se3 |
| 2.DB.05 | Metastibnite | Sb2S3 |
| 2.DB.05 | Pääkkönenite | Sb2AsS2 |
| 2.DB.05 | Bismuthinite | Bi2S3 |
| 2.DB.05 | Stibnite | Sb2S3 |
| 2.DB.05 | Guanajuatite | Bi2Se3 |
| 2.DB.10 | Suredaite | PbSnS3 |
| 2.DB.10 | Ottemannite | Sn2S3 |
| 2.DB.15 | Kashinite | Ir2S3 |
| 2.DB.15 | Bowieite | Rh2S3 |
| 2.DB.20 | Montbrayite | (Au,Ag,Sb,Bi,Pb)23(Te,Sb,Bi,Pb)38 |
| 2.DB.30 | Tarkianite | (Cu,Fe)(Re,Mo)4S8 |
| 2.DB.35 | Cameronite | Cu5-x(Cu,Ag)3+xTe10 (x = 0.43) |
| 2.DB.40 | 'Schreibersite (of Shephard)' | Cr2S3 |
Fluorescence of Edgarite
nonfluorescent
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 Edgarite
mindat.org URL:
https://www.mindat.org/min-6910.html
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References for Edgarite
Reference List:
Barkov, A. Y., Martin, R. F., Men'shikov, Y. P., Savchenko, Y. E., Thibault, Y., Laajoki, K. V. O. (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence for chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology, 138 (3) 229-236 doi:10.1007/s004100050559
Jambor, John L., Puziewicz, Jacek, Roberts, Andrew C. (2000) New Mineral Names. American Mineralogist, 85 (11-12) 1843-1847
Barkov, A. Y., Martin, R. F., Men'shikov, Y. P., Savchenko, Y. E., Thibault, Y., Laajoki, K. V. O. (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence for chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology, 138 (3) 229-236 doi:10.1007/s004100050559
Localities for Edgarite
Showing 2 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.
Russia (TL) | |
| Barkov et al. (2000) +1 other reference |
| Olga Yakovleva et al. (2009) |
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Kaskasnyunchorr Mountain, Murmansk Oblast, Russia