Ferro-gedrite
A valid IMA mineral species - grandfathered
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About Ferro-gedrite
Formula:
◻Fe2+2(Fe2+3Al2)(Al2Si6O22)(OH)2
The gedrite group are orthorhombic amphiboles in the magnesium-iron-manganese amphibole subgroup defined with A(Na+K+2Ca)<0.5 apfu and C(Al+Fe3++2Ti)>1 apfu
Ferro-gedrite is defined with Fe2+ as the dominant element both in the B and C2+ positions and Al in the C3+ position.
Ferro-gedrite is defined with Fe2+ as the dominant element both in the B and C2+ positions and Al in the C3+ position.
Colour:
Pale greenish-grey to brown
Lustre:
Vitreous
Hardness:
5½ - 6
Crystal System:
Orthorhombic
Member of:
Name:
Named for its relationship to gedrite. The species was originally named ferrogedrite. The hyphen was added in 2012 by the IMA.
Unique Identifiers
Mindat ID:
1515
Long-form identifier:
mindat:1:1:1515:4
IMA Classification of Ferro-gedrite
Approved, 'Grandfathered' (first described prior to 1959)
IMA status notes:
Redefined by the IMA
IMA Formula:
◻Fe2+2(Fe2+3Al2)(Si6Al2)O22(OH)2
First published:
1939
Approval history:
Redefined IMA 2012 s.p.
Classification of Ferro-gedrite
9.DD.05
9 : SILICATES (Germanates)
D : Inosilicates
D : Inosilicates with 2-periodic double chains, Si4O11; Orthoamphiboles
9 : SILICATES (Germanates)
D : Inosilicates
D : Inosilicates with 2-periodic double chains, Si4O11; Orthoamphiboles
16.19.4
16 : Silicates Containing Aluminum and other Metals
19 : Aluminosilicates of Fe and Mg
16 : Silicates Containing Aluminum and other Metals
19 : Aluminosilicates of Fe and Mg
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Fged | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Fgd | Whitney & Evans (2010) | Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371 |
Physical Properties of Ferro-gedrite
Optical Data of Ferro-gedrite
Type:
Biaxial (-)
RI values:
nα = 1.642 - 1.694 nβ = 1.649 - 1.71 nγ = 1.661 - 1.722
2V:
Measured: 82° , Calculated: 76° to 80°
Max. Birefringence:
δ = 0.019 - 0.028
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v or r < v
Chemistry of Ferro-gedrite
Mindat Formula:
◻Fe2+2(Fe2+3Al2)(Al2Si6O22)(OH)2
The gedrite group are orthorhombic amphiboles in the magnesium-iron-manganese amphibole subgroup defined with A(Na+K+2Ca)<0.5 apfu and C(Al+Fe3++2Ti)>1 apfu
Ferro-gedrite is defined with Fe2+ as the dominant element both in the B and C2+ positions and Al in the C3+ position.
The gedrite group are orthorhombic amphiboles in the magnesium-iron-manganese amphibole subgroup defined with A(Na+K+2Ca)<0.5 apfu and C(Al+Fe3++2Ti)>1 apfu
Ferro-gedrite is defined with Fe2+ as the dominant element both in the B and C2+ positions and Al in the C3+ position.
Element Weights:
Common Impurities:
Ti,Mn,Ca,Na,K,F
Crystallography of Ferro-gedrite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Setting:
Pnma
Cell Parameters:
a = 18.52 Å, b = 17.94 Å, c = 5.31 Å
Ratio:
a:b:c = 1.032 : 1 : 0.296
Unit Cell V:
1,764.24 ų (Calculated from Unit Cell)
Z:
4
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 8.23 Å | (100) |
| 3.043 Å | (75) |
| 3.221 Å | (20) |
| 8.95 Å | (12) |
| 4.632 Å | (10) |
| 2.679 Å | (10) |
| 2.581 Å | (10) |
Comments:
Mt. Yakushi, Japan.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 9 : Lava/xenolith minerals (hornfels, sanidinite facies) | |
| Near-surface Processes | |
| 26 : Hadean detrital minerals | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Synonyms of Ferro-gedrite
Other Language Names for Ferro-gedrite
Relationship of Ferro-gedrite to other Species
Member of:
Other Members of Gedrite Root Name Group:
| Gedrite | ◻Mg2(Mg3Al2)(Al2Si6O22)(OH)2 | Orth. mmm(2/m2/m2/m) |
Common Associates
Associations Based on Photo Data:
| 1 photo of Ferro-gedrite associated with Gehlenite | Ca2Al[AlSiO7] |
| 1 photo of Ferro-gedrite associated with Chlorite Group | |
| 1 photo of Ferro-gedrite associated with Talc | Mg3Si4O10(OH)2 |
| 1 photo of Ferro-gedrite associated with Siderophyllite | KFe2+2Al(Al2Si2O10)(OH)2 |
Related Minerals - Strunz-mindat Grouping
| 9.DD.05 | Suenoite | ◻Mn2+2Mg5Si8O22(OH)2 |
| 9.DD.05 | Proto-ferro-anthophyllite | ◻Fe2+2Fe2+5(Si8O22)(OH)2 |
| 9.DD.05 | Proto-ferro-suenoite | ◻Mn2+2(Fe2+5)(Si8O22)(OH)2 |
| 9.DD.05 | Papikeite | NaMg2(Mg3Al2}(Al3Si5O22)(OH)2 |
| 9.DD.05 | Gedrite | ◻Mg2(Mg3Al2)(Al2Si6O22)(OH)2 |
| 9.DD.05 | Holmquistite | ◻Li2(Mg3Al2)(Si8O22)(OH)2 |
| 9.DD.05 | 'Sodic-anthophyllite' | {Na}{Mg2}{Mg5}(AlSi7O22)(OH)2 |
| 9.DD.05 | 'Sodic-ferro-anthophyllite' | NaFe2+2Fe2+5(AlSi7O22)(OH)2 |
| 9.DD.05 | Ferro-papikeite | NaFe2+2(Fe2+3Al2)(Si5Al3O22)(OH)2 |
| 9.DD.05 | Ferro-anthophyllite | ◻Fe2+2Fe2+5(Si8O22)(OH)2 |
| 9.DD.05 | Proto-anthophyllite | ◻Mg2Mg5(Si8O22)(OH)2 |
| 9.DD.05 | 'Ferri-holmquistite' | ◻{Li2}{Mg3Fe3+2}(Si8O22)(OH)2 |
| 9.DD.05 | Ferro-ferri-holmquistite | ◻Li2(Fe2+3Fe3+2)(Si8O22)(OH)2 |
| 9.DD.05 | Ferro-holmquistite | ◻Li2(Fe2+3Al2)(Si8O22)(OH)2 |
| 9.DD.05 | Anthophyllite | ◻Mg2Mg5(Si8O22)(OH)2 |
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 Ferro-gedrite
mindat.org URL:
https://www.mindat.org/min-1515.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Ferro-gedrite
Localities for Ferro-gedrite
Showing 17 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.
Canada | |
| Neyedley et al. (2017) |
Czech Republic | |
| Mücke et al. (2006) |
| Schreyer et al. (1993) |
| Staněk (1997) | |
Finland | |
| Probed |
Germany | |
| Baumgärtl (2014) |
| Wittern (2001) |
| Wittern (2001) |
Greenland | |
| Petersen et al. (1993) |
India | |
| Mineralogical Magazine (1967) |
Japan | |
| RRUFF Project specimen ID # R060330 +3 other references |
| Seki et al. (1957) |
Norway | |
| Terje Karstensen collection ( pers.info. to Knut Edvard Larsen 16.10.2014) +1 other reference |
Russia | |
| Barkov et al. (2021) |
USA | |
| Smith (2005) |
| John H. Betts (2009) |
| William S. Cordua collection |
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Kawai mine, Ena City, Gifu Prefecture, Japan