Log In
Middendorfite
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Middendorfite
Alexander Theodor von Middendorff
Formula:
K3Na2Mn5Si12(O,OH)36 · 2H2O
Colour:
Dark to bright orange
Lustre:
Vitreous
Hardness:
3 - 3½
Specific Gravity:
2.60
Crystal System:
Monoclinic
Name:
For Aleksandr Fedorovich von Middendorf (18 August 1815 – 24 January 1894), a German-Russian scientist who made the first mineralogical studies on the Khibiny massif.
Unique Identifiers
Mindat ID:
28996
Long-form identifier:
mindat:1:1:28996:8
IMA Classification of Middendorfite
Approved
IMA Formula:
K3Na2Mn2+5Si12(O,OH)36·2H2O
Approval year:
2005
First published:
2006
Classification of Middendorfite
9.EJ.10
9 : SILICATES (Germanates)
E : Phyllosilicates
J : Unclassified phyllosilicates
9 : SILICATES (Germanates)
E : Phyllosilicates
J : Unclassified phyllosilicates
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 |
|---|---|---|
| Mdd | 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 Middendorfite
Vitreous
Transparency:
Transparent
Colour:
Dark to bright orange
Streak:
Yellowish
Hardness:
3 - 3½ on Mohs scale
Tenacity:
Flexible
Cleavage:
Perfect
on (001)
on (001)
Fracture:
Sub-Conchoidal
Comment:
fracture scaly
Density:
2.60 g/cm3 (Measured) 2.65 g/cm3 (Calculated)
Optical Data of Middendorfite
Type:
Biaxial (-)
RI values:
nα = 1.534(3) nβ = 1.562(2) nγ = 1.563(2)
2V:
Measured: 10° (5), Calculated: 21°
Max. Birefringence:
δ = 0.029
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:
Low (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.
Pleochroism:
Strong
Comments:
X = yellowish to colorless; Y = brown;
Z = deep brown
Z = deep brown
Chemistry of Middendorfite
Mindat Formula:
K3Na2Mn5Si12(O,OH)36 · 2H2O
Element Weights:
Crystallography of Middendorfite
Crystal System:
Monoclinic
Cell Parameters:
a = 12.55(1) Å, b = 5.721(2) Å, c = 26.86(2) Å
β = 114.04(7)°
β = 114.04(7)°
Ratio:
a:b:c = 2.194 : 1 : 4.695
Unit Cell V:
1761 ų
Z:
2
Comment:
Point Group: 2/m or 2; Space Group: P21/m or P21.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 12.28 Å | (100) |
| 2.840 Å | (90) |
| 2.634 Å | (88) |
| 4.31 Å | (81) |
| 2.366 Å | (76) |
| 1.669 Å | (64) |
| 3.555 Å | (62) |
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 Middendorfite
General Appearance of Type Material:
Coarse, rhomb-like lamellar and tabular crystals up to 0.1 x 0.2 x 0.4 mm in size, combined in worm- and fan-like aggregates up to 1 mm
Place of Conservation of Type Material:
A.E. Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, 3312/1.
Geological Setting of Type Material:
late hydrothermal mineral in a hyperperalkaline pegmatite
Associated Minerals at Type Locality:
Synonyms of Middendorfite
Other Language Names for Middendorfite
Dutch:Middendorfiet
German:Middendorfit
Related Minerals - Strunz-mindat Grouping
| 9.EJ.05 | Lourenswalsite | (K,Ba)2(Ti,Mg,Ca,Fe)4(Si,Al,Fe)6O14(OH)12 |
| 9.EJ.15 | Lipuite | KNa8Mn3+5 Mg0.5[Si12O30(OH)4](PO4)O2(OH)2 · 4H2O |
| 9.EJ.20 | Odigitriaite | CsNa5Ca5[Si14B2O38]F2 |
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) | 8.4567% | 2,622 | 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
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 Middendorfite
mindat.org URL:
https://www.mindat.org/min-28996.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Middendorfite
Reference List:
Localities for Middendorfite
Showing 1 localities.
ⓘ - 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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
- 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 (TL) | |
| Pekov et al. (2006) |
Quick NavTopAbout MiddendorfiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesStrunz-MindatRadioactivityOther InformationInternet Links References Localities
Hilairitovoye pegmatite, 252 m level, Kirovskii apatite mine, Kukisvumchorr Mt, Murmansk Oblast, Russia