Letnikovite-(Ce)
A valid IMA mineral species - pending publication
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Formula:
(Na◻)Ca2Ce2[Si7O17(OH)]F4(H2O)4
Colour:
colorless
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
2.847 (Calculated)
Crystal System:
Monoclinic
Name:
named for Professor Felix Artem’evich Letnikov (Russian Cyrillic: Феликс Артемьевич Летников) (born October 3, 1934, Polotsk, USSR), Academician of the Russian Academy of Sciences, a prominent geologist working on the petrology and geochemistry of Precambrian rocks.
New structure type. Chemical combination is somewhat similar to (more complex) semenovite-(Ce).
This is the first occurrence of a single [Si7O17(OH)]7– sheet in a mineral.
This is the first occurrence of a single [Si7O17(OH)]7– sheet in a mineral.
Unique Identifiers
Mindat ID:
470698
Long-form identifier:
mindat:1:1:470698:0
IMA Classification of Letnikovite-(Ce)
Classification of Letnikovite-(Ce)
9.DN.
9 : SILICATES (Germanates)
D : Inosilicates
N : Inosilicates with 6-periodic double chains
9 : SILICATES (Germanates)
D : Inosilicates
N : Inosilicates with 6-periodic double chains
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 |
|---|---|---|
| Lkv-Ce | 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 Letnikovite-(Ce)
Vitreous
Colour:
Colorless
Streak:
White
Hardness:
4 on Mohs scale
Hardness:
VHN50=239 kg/mm2 - Vickers
Tenacity:
Brittle
Cleavage:
Perfect
{001}
{001}
Parting:
none
Fracture:
Irregular/Uneven, Step-Like
Comment:
fracture is stepped along the cleavage plane and uneven across this direction
Density:
2.847 g/cm3 (Calculated)
Chemistry of Letnikovite-(Ce)
Mindat Formula:
(Na◻)Ca2Ce2[Si7O17(OH)]F4(H2O)4
Element Weights:
Crystallography of Letnikovite-(Ce)
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/m
Setting:
C2/m
Cell Parameters:
a = 7.4726(3) Å, b = 22.9196(9) Å, c = 13.9360(6) Å
β = 105.550(5)°
β = 105.550(5)°
Ratio:
a:b:c = 0.326 : 1 : 0.608
Unit Cell V:
2,299.44 ų (Calculated from Unit Cell)
Z:
4
Twinning:
Macroscopically, the crystals do not show twinning, but have
microscopic twinning.
microscopic twinning.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.527 Å | (67) |
| 3.357 Å | (54) |
| 3.221 Å | (58) |
| 3.140 Å | (100) |
| 3.048 Å | (60) |
| 2.896 Å | (65) |
| 2.242 Å | (50) |
| 1.882 Å | (56) |
Type Occurrence of Letnikovite-(Ce)
General Appearance of Type Material:
isolated prismatic grains up to 0.03 x 0.1 mm in a quartz-pectolite aggregate.
Place of Conservation of Type Material:
collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18-2, Moscow 119071, Russia, registration number 5924/1
Geological Setting of Type Material:
in a silexite-like peralkaline pegmatite and was formed at a late, probably hydrothermal, stage of the pegmatite.
Associated Minerals at Type Locality:
Other Language Names for Letnikovite-(Ce)
Dutch:Letnikoviet-(Ce)
German:Letnikovit-(Ce)
Related Minerals - Strunz-mindat Grouping
| 9.DN.05 | Zektzerite | LiNaZrSi6O15 |
| 9.DN.05 | Emeleusite | Li2Na4Fe2Si12O30 |
| 9.DN.05 | Tuhualite | NaFe2+Fe3+Si6O15 |
| 9.DN.10 | Semenovite-(Ce) | Na8Ca2FeBe6Ce2Si14O40(OH)4F4 |
| 9.DN.15 | Ashcroftine-(Y) | K5Na5(Y,Ca)12Si28O70(OH)2(CO3)8 · 8H2O |
| 9.DN.15 | Ashcroftine-(Ce) | K5Na5(Ce,Ca)12Si28O70(OH)2(CO3)8 · 8H2O |
Fluorescence of Letnikovite-(Ce)
none
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 Letnikovite-(Ce)
mindat.org URL:
https://www.mindat.org/min-470698.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Letnikovite-(Ce)
Reference List:
Localities for Letnikovite-(Ce)
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.
Tajikistan (TL) | |
| Bosi et al. (2023) |