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Edgarite

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About EdgariteHide

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.
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 reduced Nb cations.


Classification of EdgariteHide

Approved
Approval Year:
1995
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
Dana 7th ed.:
2.11.13.1

Physical Properties of EdgariteHide

Metallic
Transparency:
Opaque
Colour:
Dark grey
Hardness:
2 - 2½ on Mohs scale
Hardness:
VHN100=135 (5 s test time) - Vickers
Cleavage:
Perfect
basal
Density:
4.99 g/cm3 (Calculated)

Optical Data of EdgariteHide

Type:
Anisotropic
Anisotropism:
White to dark brown
Reflectivity:
8.1nmR=8.%
27.4nmR=0.2(470%
27.0nmR=9.3(546%
27.0nmR=8.5(589%
nmR=6.9(650%

Reflectance graph
Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 9.3(546%.
Pleochroism:
Strong
Comments:
Grey to light grey with a bluish tint
Comments:
Anisotropy strong.

Chemical Properties of EdgariteHide

Formula:
FeNb3S6

FeNb3+2Nb4+S6
Common Impurities:
V,Mn

Crystallography of EdgariteHide

Crystal System:
Hexagonal
Class (H-M):
6 2 2 - Trapezohedral
Space Group:
P63 2 2
Cell Parameters:
a = 5.771 Å, c = 12.19 Å
Ratio:
a:c = 1 : 2.112
Unit Cell V:
351.59 ų (Calculated from Unit Cell)
Z:
2
Comment:
Space group is probable

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
6.11(80)
2.606(80)
2.096(100)
1.665(80)

Type Occurrence of EdgariteHide

General Appearance of Type Material:
Platy inclusions in Ti-(V)-rich pyrrhotite and ferroan alabandite, and as dark gray aggregates of platy grains.
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:

Synonyms of EdgariteHide

Other Language Names for EdgariteHide

German:Edgarit
Spanish:Edgarita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Pyrrhotite2 photos of Edgarite associated with Pyrrhotite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

2.DB.05AntimonseliteSb2Se3Orth. mmm (2/m 2/m 2/m)
2.DB.05BismuthiniteBi2S3Orth. mmm (2/m 2/m 2/m)
2.DB.05GuanajuatiteBi2Se3Orth. mmm (2/m 2/m 2/m) : Pnma
2.DB.05MetastibniteSb2S3Amor.
2.DB.05PääkköneniteSb2AsS2Mon. 2/m : B2/m
2.DB.05StibniteSb2S3Orth. mmm (2/m 2/m 2/m)
2.DB.10Ottemannitebeta Sn2S3
2.DB.10SuredaitePbSnS3Orth. mmm (2/m 2/m 2/m)
2.DB.15Bowieite(Rh,Ir,Pt)2S3Orth. mmm (2/m 2/m 2/m)
2.DB.15Kashinite(Ir,Rh)2S3Orth.
2.DB.20Montbrayite(Au,Ag,Sb,Bi,Pb)23(Te,Sb,Bi,Pb)38Tric.
2.DB.30Tarkianite(Cu,Fe)(Re,Mo)4S8Iso. 4 3m
2.DB.35CameroniteCu5-x(Cu,Ag)3+xTe10 (x = 0.43)Mon. 2/m : B2/b

Fluorescence of EdgariteHide

nonfluorescent

Other InformationHide

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 EdgariteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Barkov, A.Y., R.F. Martin, Y.P. Men'shikov, Y.E. Savchenko, Y. Thibault, and K.V.O. Laajoki (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence of chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology: 138: 229-236.
Journal of Physics and Chemistry of Solids: 31: 1057-1067.
Journal of Solid State Chemistry: 33: 361-369.
indi, L. & Martin, R.F. (2018): Edgarite, FeNb3S6, from the Khibina Alkaline Complex, Russia: Solution of the Crystal Structure. Canadian Mineralogist, 56, (in press); http://forum.amiminerals.it/viewtopic.php?f=5&t=14592 (2018)

Internet Links for EdgariteHide

Localities for EdgariteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Russia
 
  • Northern Region
    • Murmanskaya Oblast'
Olga Yakovleva, I. Pekov, I. Bryzgalov, Yu. Men’shikov, V. Yapaskurt, E. Guseva, N. Korotaeva (2009) Chalcogenide Minerals in Fenitized Xenoliths in Khibiny Alkaline Complex Kola Peninsula, Russia): Diversity and Chemical Features. Fifth International Symposium Mineral Diversity Research and Preservation pp213-216
Barkov, A.Y., R.F. Martin, Y.P. Men'shikov, Y.E. Savchenko, Y. Thibault, and K.V.O. Laajoki (2000) Edgarite, FeNb3S6, first natural niobium-rich sulfide from the Khibina alkaline complex, Russian Far North: evidence of chalcophile behavior of Nb in a fenite. Contributions to Mineralogy and Petrology: 138: 229-236; The Canadian Mineralogist (2000): 38: 1377-1385.
Mineral and/or Locality  
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