Ferri-winchite (of Leake 1978)
A discredited species name
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This name was rejected as a valid mineral, but new material has been analysed from the Ilmeny Mts in Russia and this has now been approved as a new mineral species Ferriwinchite. Localities listed below need to be re-examined, and may be better listed as localities for Ferrian Winchite.
Originally described from Kajlidongri mine, Jhabua District, Madhya Pradesh, India.
Originally described from Kajlidongri mine, Jhabua District, Madhya Pradesh, India.
Unique Identifiers
Mindat ID:
1489
Long-form identifier:
mindat:1:1:1489:8
Similar Names
| Ferri-winchite | A valid IMA mineral species | ◻(NaCa)(Mg4Fe3+)Si8O22(OH)2 |
| Ferro-winchite | A named amphibole that is NOT (yet) an approved mineral species | ◻(CaNa)(Fe42+Al)(Si8O22)(OH)2 |
IMA Classification of Ferri-winchite (of Leake 1978)
Discredited
Classification of Ferri-winchite (of Leake 1978)
14.25.2
14 : Silicates not Containing Aluminum
25 : Silicates of Fe, Ca and alkalis and of Fe, Mg, Ca and alkalis
14 : Silicates not Containing Aluminum
25 : Silicates of Fe, Ca and alkalis and of Fe, Mg, Ca and alkalis
Optical Data of Ferri-winchite (of Leake 1978)
Type:
Biaxial (-)
RI values:
nα = 1.636 nβ = 1.646 nγ = 1.658
2V:
Measured: 82° , Calculated: 86°
Max. Birefringence:
δ = 0.022
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:
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:
weak
Synonyms of Ferri-winchite (of Leake 1978)
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 Ferri-winchite (of Leake 1978)
mindat.org URL:
https://www.mindat.org/min-1489.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Ferri-winchite (of Leake 1978)
Reference List:
Localities for Ferri-winchite (of Leake 1978)
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.
Chile | |
| Willner et al. (2001) |
Russia | |
| Canadian Mineralogist 39 (1) |
