Fukalite
A valid IMA mineral species
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About Fukalite
Formula:
Ca4[Si2O6][CO3](OH)2
Colour:
Pale brown, white
Hardness:
4
Specific Gravity:
2.770
Crystal System:
Monoclinic
Name:
Named by Chiyoko Henmi, Isao Kusachi, Akira Kawahara, and Kitinosuke Henmi in 1977 after the type locality of Fuka Mine, Japan.
Dimorph of:
OD structure; six MDO polytypes are possible (Bonaccorsi et al., 2009).
Unique Identifiers
Mindat ID:
1619
Long-form identifier:
mindat:1:1:1619:9
IMA Classification of Fukalite
Approved
IMA Formula:
Ca4Si2O6(CO3)(OH)2
Approval year:
1976
First published:
1977
Classification of Fukalite
9.DQ.05
9 : SILICATES (Germanates)
D : Inosilicates
Q : Modular Inosilicate-Sorosilicate Structures
9 : SILICATES (Germanates)
D : Inosilicates
Q : Modular Inosilicate-Sorosilicate Structures
78.4.3.1
78 : Unclassified Silicates
4 :
78 : Unclassified Silicates
4 :
17.4.5
17 : Silicates Containing other Anions
4 : Silicates with carbonates
17 : Silicates Containing other Anions
4 : Silicates with carbonates
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 |
|---|---|---|
| Fk | 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 Fukalite
Colour:
Pale brown, white
Streak:
White
Hardness:
4 on Mohs scale
Density:
2.770 g/cm3 (Measured) 2.77 g/cm3 (Calculated)
Optical Data of Fukalite
Type:
Biaxial (+/-)
RI values:
nα = 1.595 nβ = 1.605 nγ = 1.626
2V:
Measured: 90° , Calculated: 70°
Max. Birefringence:
δ = 0.031
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 > v strong
Chemistry of Fukalite
Mindat Formula:
Ca4[Si2O6][CO3](OH)2
Element Weights:
Common Impurities:
Al,Fe,Mg,Na,K,P
Crystallography of Fukalite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Setting:
P121/c1
Cell Parameters:
a = 7.573(3) Å, b = 23.364(5) Å, c = 11.544(4) Å
β = 109.15(1)°
β = 109.15(1)°
Ratio:
a:b:c = 0.324 : 1 : 0.494
Unit Cell V:
1,929.52 ų (Calculated from Unit Cell)
Z:
2
Comment:
Cell conforms to one of six possible MDO types. Originally described with orthrhombic cell (5.48, 3.78, 23.42 A).
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
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View
CIF File Best | x | y | z | a | b | c
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Rotation
Stop | Start
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Labels
Console Off | On | Grey | Yellow
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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) |
|---|---|---|---|---|---|---|---|
| 0004836 | Fukalite | Merlino S, Bonaccorsi E, Grabezhev A I, Zadov A E, Pertsev N N, Chukanov N V (2009) Fukalite: An example of an OD structure with two-dimensional disorder American Mineralogist 94 323-333 |  | 2009 | Gumeshevsk skarn, Central Urals, Russia | 0 | 293 |
| 0012514 | Fukalite | Rastsvetaeva R K, Bolotina N B, Zadov A E, Chukanov N V (2005) Crystal structure of fukalite dimorph Ca4[Si2O6](CO3)(OH)2 from the Gumeshevsk Deposit the Urals Doklady Earth Sciences 405A 1347-1351 | 2005 | Gumeshevsk Deposit the Urals | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.854 Å | (100) |
| 3.084 Å | (90) |
| 2.926 Å | (65) |
| 2.338 Å | (30) |
| 1.756 Å | (30b) |
| 5.86 Å | (25) |
| 3.904 Å | (20) |
Comments:
Fuka, Japan. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Fukalite
General Appearance of Type Material:
Flaky crystals to 0.2 mm.
Place of Conservation of Type Material:
Department of Earth Sciences, Okayama University.
Geological Setting of Type Material:
Alteration product of spurrite.
Associated Minerals at Type Locality:
Synonyms of Fukalite
Other Language Names for Fukalite
Other Information
Notes:
Decomposed by acids with effervescence.
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 Fukalite
mindat.org URL:
https://www.mindat.org/min-1619.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Fukalite
Reference List:
Henmi, Chiyoko, Kusachi, Isao, Kawahara, Akira, Henmi, Kitinosuke (1977) Fukalite, a new calcium carbonate silicate hydrate mineral. Mineralogical Journal, 8 (7) 374-381 doi:10.2465/minerj.8.374
Localities for Fukalite
Showing 9 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.
Australia | |
| Bottrill |
Japan | |
| American Mineralogist |
| Bernard et al. (2004) |
| Henmi et al. (1977) |
Mexico | |
| Bernard et al. (2004) |
Romania | |
| Marincea et al. (2014, September) +1 other reference |
| Marincea et al. (2013) |
Russia | |
| American Mineralogist +1 other reference |
Turkey | |
| Armbruster et al. (2012) |
Quick NavTopAbout FukaliteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesOther InformationInternet Links References Localities Locality List
Mihara mine, Higashi-Mihara, Ibara City, Okayama Prefecture, Japan