Lermontovite
A valid IMA mineral species - grandfathered
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About Lermontovite
Mikhail Yur'evich Lermontov
Formula:
U(PO4)(OH) · H2O
Colour:
Grayish green, green
Lustre:
Silky, Dull
Specific Gravity:
4.00 - 4.50
Crystal System:
Orthorhombic
Name:
For Mikhail Yur'evich Lermontov (Михаил Юрьевич Лермонтов), (1814-1841), Russian poet
This page provides mineralogical data about Lermontovite.
Unique Identifiers
Mindat ID:
2381
Long-form identifier:
mindat:1:1:2381:4
IMA Classification of Lermontovite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
U4+PO4(OH)·H2O
Classification of Lermontovite
8.DN.15
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
N : With only large cations
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
N : With only large cations
40.4.8.2
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
4 : (AB)5(XO4)2·xH2O
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
4 : (AB)5(XO4)2·xH2O
19.11.1
19 : Phosphates
11 : Phosphates of U
19 : Phosphates
11 : Phosphates of U
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 |
|---|---|---|
| Ler | 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 Lermontovite
Silky, Dull
Transparency:
Transparent
Comment:
Silky on fractures
Colour:
Grayish green, green
Comment:
Grassy green in transmitted light
Tenacity:
Very brittle
Density:
4.00 - 4.50 g/cm3 (Measured) 4.08 g/cm3 (Calculated)
Optical Data of Lermontovite
Type:
Biaxial (-)
RI values:
nα = 1.686 - 1.69 nβ = 1.707 nγ = 1.724 - 1.726
2V:
Calculated: 88°
Max. Birefringence:
δ = 0.036 - 0.038
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 weak
Optical Extinction:
Z = c = elongation.
Pleochroism:
Visible
Comments:
In shades of green to grayish green.
Chemistry of Lermontovite
Mindat Formula:
U(PO4)(OH) · H2O
Element Weights:
Elements listed:
Crystallography of Lermontovite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Ccca
Cell Parameters:
a = 9.74(1) Å, b = 19.00(1) Å, c = 10.10(1) Å
Ratio:
a:b:c = 0.513 : 1 : 0.532
Unit Cell V:
1,869.11 ų (Calculated from Unit Cell)
Z:
12
Morphology:
Fibrous, veinlets or botyroidal masses.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.92 Å | (100) |
| 3.29 Å | (95) |
| 4.87 Å | (80) |
| 4.12 Å | (80) |
| 3.83 Å | (80) |
| 3.58 Å | (80) |
| 4.69 Å | (70) |
Comments:
Beshtau deposit, Russia. Data from Melkov et al. (1983). Particles do not diffract for more than 30-40 seconds.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Lermontovite
Geological Setting of Type Material:
Uranium bearing veins in granitic porphry stock.
Other Language Names for Lermontovite
Common Associates
Related Minerals - Strunz-mindat Grouping
| 8.DN. | Loomisite | Ba[Be2P2O8] · H2O |
| 8.DN.05 | Natrophosphate | Na6+xHxF(PO4)2 · (19+x)H2O |
| 8.DN.10 | Isoclasite | Ca2(PO4)(OH) · 2H2O |
| 8.DN.15 | 'Urphoite' | U4+6(PO4)7(OH)3 · 4H2O |
| 8.DN.20 | Vyacheslavite | U(PO4)(OH) |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 64.6777% | 16,169,425 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 0.0000% | 0 | 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
Notes:
Rapidly decomposes under the electron beam.
Health Risks:
Radioactive
Internet Links for Lermontovite
mindat.org URL:
https://www.mindat.org/min-2381.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 Lermontovite
Localities for Lermontovite
Showing 5 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.
Germany | |
| Dill et al. (2008) +1 other reference |
| Seeliger et al. (1965) +1 other reference | |
Poland | |
| Pieczka et al. (2015) +1 other reference |
Russia | |
| |
| Pekov (1998) |
Quick NavTopAbout LermontoviteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence Other LanguagesCommon AssociatesStrunz-MindatRadioactivityOther InformationInternet Links References Localities Locality List
Gremuchka ore zone, Mine no. 1, Beshtau Mountain, Lermontov, Stavropol Krai, Russia