Lobanovite
A valid IMA mineral species
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About Lobanovite
Constantin Valentinovich Lobanov
Formula:
K2Na(Fe2+4Mg2Na)Ti2[Si4O12]2O2(OH)4◻
Colour:
Straw yellow to orange
Lustre:
Vitreous
Hardness:
3
Specific Gravity:
3.161 (Calculated)
Crystal System:
Monoclinic
Member of:
Name:
First described in 1959 as "unusual light yellow and greenish fibrous astrophyllite" by E.I. Semenov from Kukisvumchorr Mt, Khibiny, Kola, Russia (Pekov 1998). Named magnesium astrophyllite for its relationship to astrophyllite and changed in 2008 to magnesioastrophyllite. It was formally described as a new mineral in 2017 (Sokolova et al.). The name lobanovite honors Dr. Constantin V. Lobanov, a Russian geologist working in the Kola Peninsula.
Co-Type Localities:
Unique combination of elements.
Note:
Originally named and published as "magnesium astrophyllite" and "magnesioastrophyllite". Validated by IMA in 2015 under the name lobanovite (IMA 15-B).
Peng & Ma (1963) established its monoclinic symmetry.
The structure is based on HOH blocks comprising one cp octahedral and two heteropolyhedral sheets; the HOH blocks repeat along [001]. The O sheet is built of M(1-4) octahedra; the H sheet is formed by T4O12 astrophyllite ribbons having common vertices with D polyhedra dominated by VTi. K and Na atoms are in the interstitial A and B sites.
Note:
Originally named and published as "magnesium astrophyllite" and "magnesioastrophyllite". Validated by IMA in 2015 under the name lobanovite (IMA 15-B).
Peng & Ma (1963) established its monoclinic symmetry.
The structure is based on HOH blocks comprising one cp octahedral and two heteropolyhedral sheets; the HOH blocks repeat along [001]. The O sheet is built of M(1-4) octahedra; the H sheet is formed by T4O12 astrophyllite ribbons having common vertices with D polyhedra dominated by VTi. K and Na atoms are in the interstitial A and B sites.
Unique Identifiers
Mindat ID:
2487
Long-form identifier:
mindat:1:1:2487:3
IMA Classification of Lobanovite
Approved
IMA Formula:
K2Na(Fe2+4Mg2Na)Ti4+2(Si4O12)2O2(OH)4
Approval year:
2015
First published:
1963
Approval history:
IMA 15-B: "magnesioastrophyllite" is validated under the name lobanovite (Hålenius et al. 2015).
Classification of Lobanovite
9.DC.05
9 : SILICATES (Germanates)
D : Inosilicates
C : Inosilicates with branched 2-periodic single chains; Si2O6 + 2SiO3 Si4O12
9 : SILICATES (Germanates)
D : Inosilicates
C : Inosilicates with branched 2-periodic single chains; Si2O6 + 2SiO3 Si4O12
69.1.1.7
69 : INOSILICATES Chains with Side Branches or Loops
1 : Chains with Side Branches or Loops with (P=2, and N=4, 2 branches)
69 : INOSILICATES Chains with Side Branches or Loops
1 : Chains with Side Branches or Loops with (P=2, and N=4, 2 branches)
14.9.31
14 : Silicates not Containing Aluminum
9 : Silicates of Ti
14 : Silicates not Containing Aluminum
9 : Silicates of Ti
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 |
|---|---|---|
| Lbv | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Lbv | Warr (2020) | Warr, L.N. (2020) Recommended abbreviations for the names of clay minerals and associated phases. Clay Minerals, 55, 261–264 doi:10.1180/clm.2020.30 |
Physical Properties of Lobanovite
Vitreous
Colour:
Straw yellow to orange
Streak:
White to yellowish-white.
Hardness:
3 on Mohs scale
Cleavage:
Perfect
Perfect cleavage parallel to (001) and moderate cleavage parallel to (010).
Perfect cleavage parallel to (001) and moderate cleavage parallel to (010).
Parting:
None observed.
Fracture:
None observed
Density:
3.161 g/cm3 (Calculated)
Comment:
Calculated from the empirical formula.
Optical Data of Lobanovite
Type:
Biaxial (-)
RI values:
nα = 1.658 nβ = 1.687 nγ = 1.71
2V:
Measured: 81.5° to 83°, Calculated: 82°
Max. Birefringence:
δ = 0.052
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, strong.
Optical Extinction:
Y = b; Z ∧ a = –5 to –6°.
Pleochroism:
Visible
Comments:
X = bright yellow; Y = pale yellowish grey; Z = grey.
Comments:
Absorption: Z < Y < X.
Chemistry of Lobanovite
Mindat Formula:
K2Na(Fe2+4Mg2Na)Ti2[Si4O12]2O2(OH)4◻
Element Weights:
Common Impurities:
Mn,F,Ca,(Nb,Al,Ba)
Crystallography of Lobanovite
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 5.3327(2) Å, b = 23.1535(9) Å, c = 10.3775(4) Å
β = 99.615(1)°
β = 99.615(1)°
Ratio:
a:b:c = 0.23 : 1 : 0.448
Unit Cell V:
1263.3 ų
Z:
2
Morphology:
Elongated blades.
Twinning:
None observed.
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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Perspective On | Perspective Off
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2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
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) |
|---|---|---|---|---|---|---|---|
| 0009902 | Lobanovite | Shi N, Ma Z, Li G, Yamnova M A, Pushcharovsky D Y (1998) Structure refinement of monoclinic astrophyllite Acta Crystallographica B54 109-114 |  | 1998 | Khibina alkaline massif, Russia | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.38 100 Å | (003) |
| 2.548 90 Å | (063) |
| 10.1 80 Å | (001) |
| 3.80 60 Å | (042 131) |
| 3.079 50 Å | (132 062) |
| 2.763 90 Å | (⎯171) |
Comments:
The data are given in Sokolova et al. (2017) but are from the X-ray Laboratory, Hubei Geologic College (1974).
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks |
Type Occurrence of Lobanovite
Co-Type Localities:
General Appearance of Type Material:
Elongated bladed crystals up to 0.04 mm wide and 0.2 mm long.
Geological Setting of Type Material:
Pegmatitic cavities.
Associated Minerals at Type Locality:
Synonyms of Lobanovite
Other Language Names for Lobanovite
Dutch:Lobanoviet
German:Lobanovit
Relationship of Lobanovite to other Species
Member of:
Other Members of Devitoite Group:
| Devitoite | Ba4Ba2Fe2+7Fe3+2[Si4O12]2[PO4]2[CO3]O2(OH)4◻2 | Tric. 1 : P1 |
| Sveinbergeite | (H2O)2[Ca(H2O)](Fe2+6Fe3+)Ti2[Si4O12]2O2(OH)4[(OH)(H2O)] | Tric. 1 : P1 |
Common Associates
Associations Based on Photo Data:
| 6 photos of Lobanovite associated with Aegirine | NaFe3+Si2O6 |
| 5 photos of Lobanovite associated with Lamprophyllite | (Na,Mn2+)3(Sr,Na)2(Ti,Fe3+)3(Si2O7)2O2(OH,O,F)2 |
| 5 photos of Lobanovite associated with Nepheline | Na3K(Al4Si4O16) |
| 3 photos of Lobanovite associated with Microcline | K(AlSi3O8) |
| 2 photos of Lobanovite associated with Natisite | Na2Ti(SiO4)O |
| 1 photo of Lobanovite associated with Eudialyte | Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2 |
Related Minerals - Strunz-mindat Grouping
| 9.DC. | Bulgakite | Li2CaFe2+7Ti2[Si4O12]2O2(OH)4O(H2O)2 |
| 9.DC.05 | Devitoite | Ba4Ba2Fe2+7Fe3+2[Si4O12]2[PO4]2[CO3]O2(OH)4◻2 |
| 9.DC.05 | Zircophyllite | K2NaFe2+7Zr2[Si4O12]2O2(OH)4F |
| 9.DC.05 | Nalivkinite | Li2NaFe2+7Ti2[Si4O12]2O2(OH)4F(H2O)2 |
| 9.DC.05 | Sveinbergeite | (H2O)2[Ca(H2O)](Fe2+6Fe3+)Ti2[Si4O12]2O2(OH)4[(OH)(H2O)] |
| 9.DC.05 | Niobophyllite | K2NaFe2+7(NbTi)[Si4O12]2O2(OH)4O |
| 9.DC.05 | Heyerdahlite | Na2NaMn2+7Ti2[Si4O12]2O2(OH)4F(H2O)2 |
| 9.DC.05 | Tarbagataite | (K◻)CaFe2+7Ti2[Si4O12]2O2(OH)4(OH) |
| 9.DC.05 | Astrophyllite | K2NaFe2+7Ti2[Si4O12]2O2(OH)4F |
| 9.DC.05 | 'Hydroastrophyllite' | [H3O]+2CaFe2+7Ti2[Si4O12]2O2(OH)4O |
| 9.DC.05 | Niobokupletskite | K2NaMn2+7(NbTi)[Si4O12]2O2(OH)4O |
| 9.DC.05 | Kupletskite-(Cs) | Cs2NaMn2+7Ti2[Si4O12]2O2(OH)4F |
| 9.DC.05 | Kupletskite | K2NaMn2+7Ti2[Si4O12]2O2(OH)4F |
| 9.DC.05 | Laverovite | K2NaMn2+7Zr2[Si4O12]2O2(OH)4F |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 6.5131% | 2,019 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Other Information
Thermal Behaviour:
The DTA curve shows endothermic peaks at 835°C (strong, escape of OH) and 900°C (weak).
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 Lobanovite
mindat.org URL:
https://www.mindat.org/min-2487.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Lobanovite
Reference List:
Fleischer, Michael, Chao, G. Y., Cabri, L. J. (1975) New mineral names. American Mineralogist, 60 (7-8) 736-739 (as monoclinic magnesium astrophyllite)
Sokolova, Elena, Cámara, Fernando (2008) Re-investigation of the crystal structure of magnesium astrophyllite. European Journal of Mineralogy, 20 (2) 253-260 doi:10.1127/0935-1221/2008/0020-1796
Burke, Ernst A. J. (2008) Tidying up mineral names: an IMA-CNMNC scheme for suffixes, hyphens and diacritical marks. The Mineralogical Record, 39 (2) 131-135
Hålenius, U., Hatert, F., Pasero, M., Mills, S. J. (2015) New minerals and nomenclature modifications approved in 2015, CNMNC Newsletter 26. Mineralogical Magazine, 79 (4) 941-947 doi:10.1180/minmag.2015.079.4.05
Sokolova, Elena, Cámara, Fernando, Hawthorne, Frank C., Semenov, Evgeny I., Ciriotti, Marco E. (2017) Lobanovite, K2Na(Fe42+Mg2Na)Ti2(Si4O12)2O2(OH)4, a new mineral of the astrophyllite supergroup and its relation to magnesioastrophyllite. Mineralogical Magazine, 81 (1) 175-181 doi:10.1180/minmag.2016.080.088
Localities for Lobanovite
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.
Russia | |
| Mandarino (1997) |
| [World of Stones 95:5-6 +1 other reference |
| Pekov (1998) |
| Pekov (1998) | |
| ... | |
| Takai et al. (2011) | |
| Pekov I.V. et al. (2010) |
| Pekov (1998) +1 other reference |
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Yukspor Mountain, Murmansk Oblast, Russia