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Fedorovskite
A valid IMA mineral species
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About Fedorovskite
Formula:
Ca2Mg2B4O7(OH)6
Colour:
Brown
Lustre:
Vitreous
Hardness:
4½
Specific Gravity:
2.65
Crystal System:
Orthorhombic
Name:
Named for Nikolai Mikhailovich Fedorovskii (1886-1956), Russian crystallographer, mineralogist and founder of the Russian Research Institute of Mineral Resources, Moscow, Russia.
Unique Identifiers
Mindat ID:
1468
Long-form identifier:
mindat:1:1:1468:3
IMA Classification of Fedorovskite
Approved
Approval year:
1975
First published:
1977
Classification of Fedorovskite
6.DA.25
6 : BORATES
D : Tetraborates
A : Neso-tetraborates
6 : BORATES
D : Tetraborates
A : Neso-tetraborates
Dana 7th ed.:
25.4.1.2
25.4.1.2
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
4 : Tetraborates
25 : ANHYDROUS BORATES CONTAINING HYDROXYL OR HALOGEN
4 : Tetraborates
9.4.2
9 : Borates
4 : Borates of Ca and Mn
9 : Borates
4 : Borates of Ca and Mn
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 |
|---|---|---|
| Fdo | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Fedorovskite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Fedorovskite
Vitreous
Transparency:
Translucent
Colour:
Brown
Streak:
Pale brown
Hardness:
4½ on Mohs scale
Cleavage:
Perfect
Perfect on {100}
Perfect on {100}
Density:
2.65 g/cm3 (Measured) 2.60 g/cm3 (Calculated)
Optical Data of Fedorovskite
Type:
Biaxial (-)
RI values:
nα = 1.619 - 1.623 nβ = 1.627 - 1.632 nγ = 1.629 - 1.634
2V:
Measured: 48°
Max. Birefringence:
δ = 0.010 - 0.011
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:
r
Pleochroism:
Visible
Comments:
X= colorless to pale yellow
Z= yellow to bright yellow
Z= yellow to bright yellow
Chemistry of Fedorovskite
Mindat Formula:
Ca2Mg2B4O7(OH)6
Element Weights:
Crystallography of Fedorovskite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbam
Cell Parameters:
a = 8.96(2) Å, b = 13.15(2) Å, c = 8.15(1) Å
Ratio:
a:b:c = 0.681 : 1 : 0.62
Unit Cell V:
960.27 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Prismatic crystals, with rhombic outlines, fibrous aggregates.
Twinning:
Polysynthetic, composition plane {100}
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.92 Å | (100) |
| 3.02 Å | (70) |
| 2.59 Å | (100) |
| 2.28 Å | (60) |
| 2.119 Å | (70) |
| 1.693 Å | (70) |
| 1.630 Å | (70) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Geological Setting:
Skarn type boron deposit.
Type Occurrence of Fedorovskite
General Appearance of Type Material:
Mono-mineral veinlets, commonly fibrous
Place of Conservation of Type Material:
A. E. Fersman Mineralogical Museum, Academy of Science, Moscow, Russia.
Associated Minerals at Type Locality:
Synonyms of Fedorovskite
Other Language Names for Fedorovskite
Relationship of Fedorovskite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 3 photos of Fedorovskite associated with Kurchatovite | Ca(Mg,Mn2+)[B2O5] |
| 2 photos of Fedorovskite associated with Ludwigite | Mg2Fe3+(BO3)O2 |
| 1 photo of Fedorovskite associated with Borcarite | Ca4Mg(B4O6(OH)6)(CO3)2 |
| 1 photo of Fedorovskite associated with Roweite | Ca2Mn2+2B4O7(OH)6 |
| 1 photo of Fedorovskite associated with Frolovite | Ca[B(OH)4]2 |
| 1 photo of Fedorovskite associated with Szaibélyite | MgBO2(OH) |
Related Minerals - Strunz-mindat Grouping
| 6.DA.10 | Borax | Na2(B4O5)(OH)4 · 8H2O |
| 6.DA.15 | Tincalconite | Na2(B4O7) · 5H2O |
| 6.DA.20 | Hungchaoite | Mg(B4O7) · 9H2O |
| 6.DA.25 | Roweite | Ca2Mn2+2B4O7(OH)6 |
| 6.DA.30 | Hydrochlorborite | Ca4B8O15Cl2 · 21H2O |
| 6.DA.35 | Uralborite | Ca2[B3O3(OH)5 · OB(OH)3] |
| 6.DA.40 | Numanoite | Ca4Cu(B4O6(OH)6)(CO3)2 |
| 6.DA.40 | Borcarite | Ca4Mg(B4O6(OH)6)(CO3)2 |
| 6.DA.60 | Fontarnauite | (Na,K)2(Sr,Ca)(SO4)[B5O8(OH)] · 2H2O |
Other Information
Notes:
Insoluble in H2O, dissolved by dilute HCl
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 Fedorovskite
mindat.org URL:
https://www.mindat.org/min-1468.html
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References for Fedorovskite
Localities for Fedorovskite
Showing 4 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.
Japan | |
| Kobayashi et al. (2020) |
Mexico | |
| Christopher Emproto |
| Carnegie Museum of Natural History ... +1 other reference | |
Russia (TL) | |
| Malinko et al. (1972) +2 other references |
Quick NavTopAbout FedorovskiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPronunciation Physical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Solongo B deposit, Ozernoe ore cluster, Yeravninsky District, Buryatia, Russia