Osumilite-(Mg)
About Osumilite-(Mg)
Mg-dominant (at the octahedral site) analogues of osumilite have been described several times (Armbruster and Oberhänsli, 1988; Balassone et al., 2008; Seryotkin et al., 2008), but published without approval by the CNMNC.
The mineral was finally approved as a valid species by the IMA in 2011, based upon a complete investigation of a type specimen from Bellerberg, Eifel, Rheinland-Pfalz, Germany (Chukanov et al., 2013).
Note: All localities listed here should be checked if they are to be assigned under osumilite-(Mg) or osumilite.
Unique Identifiers
Similar Names
| Osmelite | A synonym of Pectolite | |
| Osumilite | A valid IMA mineral species - grandfathered | K◻2Fe22+Al3[Al2Si10O30] |
| Osumilite-(K,Mg) | A discredited species name |
IMA Classification of Osumilite-(Mg)
Classification of Osumilite-(Mg)
9 : SILICATES (Germanates)
C : Cyclosilicates
M : [Si6O18]12- 6-membered double rings (sechser-Doppelringe)
16 : Silicates Containing Aluminum and other Metals
24 : Aluminosilicates of Fe, Mg, Ca and alkalis
Mineral Symbols
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Osm-Mg | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Osm | Whitney & Evans (2010) | Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371 |
| Osm | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Osumilite-(Mg)
Optical Data of Osumilite-(Mg)
Based on recorded range of RI values above.
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.
Relative to Canada balsam mounting medium (n ≈ 1.537).
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Chemistry of Osumilite-(Mg)
Chemical Analysis
| 1 | |
|---|---|
| Ba | |
| Al | 12.1462875 % |
| Ti | 0.1318548 % |
| Fe | 3.070335 % |
| Mn | 0.10067980000000001 % |
| Mg | 4.2333408 % |
| Na | 0.43769739999999996 % |
| K | 3.436821 % |
| Cr | |
| Ca | |
| O | 47.5942346 % |
| Si | 28.2187491 % |
| SiO2 | 60.37 % |
| Al2O3 | 22.95 % |
| TiO2 | 0.22 % |
| FeO (tot.) | 3.95 % |
| MnO | 0.13 % |
| MgO | 7.02 % |
| Na2O | 0.59 % |
| K2O | 4.14 % |
| Cr2O3 | tr. % |
| CaO | tr. % |
| BaO | tr. % |
| Total: | 198.74 % |
| Sample ID | Empirical Formula |
|---|---|
| 1 | (K0.80Na0.19)(Mg1.46Fe2+0.55Mn0.02)(Al2.67Ti0.03Mg0.30)(Si10.13Al1.87)O30 |
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Roadcut Fv 503 Vikesdal, Vikeså, Bjerkreim, Rogaland, Norway | Analysed with electron microprobe |
Crystallography of Osumilite-(Mg)
Common crystal faces are {100} and {001} with rare {101} and {110}.
X-Ray Powder Diffraction
| d-spacing | Intensity |
|---|---|
| 7.21 Å | (37) |
| 5.538 Å | (36) |
| 5.064 Å | (85) |
| 4.137 Å | (45) |
| 3.736 Å | (43) |
| 3.234 Å | (100) |
| 2.932 Å | (42) |
| 2.767 Å | (51) |
Geological Environment
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4a: Earth’s earliest continental crust | >4.4-3.0 |
| 20 : Acidic volcanic rocks | |
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Osumilite-(Mg)
Synonyms of Osumilite-(Mg)
Other Language Names for Osumilite-(Mg)
Relationship of Osumilite-(Mg) to other Species
| Agakhanovite-(Y) | K◻2(YCa)Be3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Almarudite | K◻2Mn2+2(Be2Al)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mmm |
| Aluminosugilite | KNa2Al2Li3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Armenite | Ba(H2O)2Ca2Al3[Al3Si9O30] | Orth. mmm(2/m2/m2/m) : Pnna |
| Berezanskite | K◻2Ti2Li3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Brannockite | K◻2Sn2Li3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Chayesite | K◻2Mg2(Mg2Fe3+)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Darapiosite | KNa2Mn2(Zn2Li)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Dusmatovite | K(K◻)Mn2+2Zn3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Eifelite | KNa2(MgNa)Mg3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Friedrichbeckeite | K(◻Na)Mg2(Be2Mg)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Klöchite | K◻2(Fe2+Fe3+)Zn3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P63/mmc |
| Laurentthomasite | K◻2Mg2(Be2Al)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Merrihueite | K(◻Na)Fe2+2Fe2+3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Milarite | K(◻H2O)Ca2(Be2Al)[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Oftedalite | K◻2(ScCa)Be3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Osumilite | K◻2Fe2+2Al3[Al2Si10O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Plechovite | Ca2[K(H2O)]KBe3Si12O30 | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Poudretteite | K◻2Na2B3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Roedderite | K(◻Na)Mg2Mg3[Si12O30] | Hex. 6m2 : P62c |
| Shibkovite | K(◻K)Ca2Zn3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Sogdianite | K◻2Zr2Li3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Sugilite | KNa2Fe3+2Li3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| Trattnerite | ◻(◻)2Fe3+2Mg3[Si12O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
| 'UM1990-73-SiO:KMnNaZn' | K(KNa0.5◻0.5)(Mn1.5Na0.5)Zn3[Si12O30] | Hex. |
| 'Unnamed (Mn3+-dominant analog of Sugilite)' | KNa2Mn3+2Li3[Si12O30] | |
| Yagiite | Na◻2Mg2Al3[Al2Si10O30] | Hex. 6/mmm(6/m2/m2/m) : P6/mcc |
Common Associates
| 17 photos of Osumilite-(Mg) associated with Mullite | Al4+2xSi2-2xO10-x |
| 12 photos of Osumilite-(Mg) associated with Hematite | Fe2O3 |
| 12 photos of Osumilite-(Mg) associated with Cordierite | Mg2Al4Si5O18 |
| 5 photos of Osumilite-(Mg) associated with Tridymite | SiO2 |
| 3 photos of Osumilite-(Mg) associated with Plagioclase | (Na,Ca)[(Si,Al)AlSi2]O8 |
| 3 photos of Osumilite-(Mg) associated with Pseudobrookite | Fe3+2Ti4+O5 |
| 2 photos of Osumilite-(Mg) associated with Sanidine | K(AlSi3O8) |
| 2 photos of Osumilite-(Mg) associated with K Feldspar | |
| 2 photos of Osumilite-(Mg) associated with Phlogopite | KMg3(AlSi3O10)(OH)2 |
| 1 photo of Osumilite-(Mg) associated with Orthopyroxene Subgroup |
Related Minerals - Strunz-mindat Grouping
| 9.CM. | Agakhanovite-(Y) | K◻2(YCa)Be3[Si12O30] |
| 9.CM. | Plechovite | Ca2[K(H2O)]KBe3Si12O30 |
| 9.CM.05 | Friedrichbeckeite | K(◻Na)Mg2(Be2Mg)[Si12O30] |
| 9.CM.05 | Laurentthomasite | K◻2Mg2(Be2Al)[Si12O30] |
| 9.CM.05 | 'UM1990-73-SiO:KMnNaZn' | K(KNa0.5◻0.5)(Mn1.5Na0.5)Zn3[Si12O30] |
| 9.CM.05 | Eifelite | KNa2(MgNa)Mg3[Si12O30] |
| 9.CM.05 | Almarudite | K◻2Mn2+2(Be2Al)[Si12O30] |
| 9.CM.05 | Armenite | Ba(H2O)2Ca2Al3[Al3Si9O30] |
| 9.CM.05 | Merrihueite | K(◻Na)Fe2+2Fe2+3[Si12O30] |
| 9.CM.05 | Oftedalite | K◻2(ScCa)Be3[Si12O30] |
| 9.CM.05 | Roedderite | K(◻Na)Mg2Mg3[Si12O30] |
| 9.CM.05 | Shibkovite | K(◻K)Ca2Zn3[Si12O30] |
| 9.CM.05 | Sogdianite | K◻2Zr2Li3[Si12O30] |
| 9.CM.05 | Milarite | K(◻H2O)Ca2(Be2Al)[Si12O30] |
| 9.CM.05 | Berezanskite | K◻2Ti2Li3[Si12O30] |
| 9.CM.05 | Poudretteite | K◻2Na2B3[Si12O30] |
| 9.CM.05 | Darapiosite | KNa2Mn2(Zn2Li)[Si12O30] |
| 9.CM.05 | Chayesite | K◻2Mg2(Mg2Fe3+)[Si12O30] |
| 9.CM.05 | Osumilite | K◻2Fe2+2Al3[Al2Si10O30] |
| 9.CM.05 | Sugilite | KNa2Fe3+2Li3[Si12O30] |
| 9.CM.05 | Trattnerite | ◻(◻)2Fe3+2Mg3[Si12O30] |
| 9.CM.05 | Brannockite | K◻2Sn2Li3[Si12O30] |
| 9.CM.05 | Klöchite | K◻2(Fe2+Fe3+)Zn3[Si12O30] |
| 9.CM.05 | Dusmatovite | K(K◻)Mn2+2Zn3[Si12O30] |
| 9.CM.05 | Yagiite | Na◻2Mg2Al3[Al2Si10O30] |
| 9.CM.9.CM. | Aluminosugilite | KNa2Al2Li3[Si12O30] |
| 9.CM.10 | Faizievite | K2Na(Ca6Na)Ti4Li6[Si6O18]2[Si12O30]F2 |
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) | 3.9756% | 1,232 | 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.
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
Main absorption bands (cm–1, s = strong, sh = shoulder):
1138s, 1000sh, 950s [stretching vibrations of (Si,Al)O4 tetrahedra], 770sh, 745, 717, 652, 541s (mixed vibrations of tetrahedral rings), 475, 440, 401s, 378s (combined modes with bending vibrations Si-O-Si and stretching vibrations of Mg octahedra).
For osumilite the wavenumber of the latter band is lower (367 cm–1) due to the predominance of Fe+2 over Mg in the octahedral site. The bands related to H-, B-, or C-bearing groups are absent in IR spectrum
Internet Links for Osumilite-(Mg)
Please feel free to link to this page.
References for Osumilite-(Mg)
Localities for Osumilite-(Mg)
Showing 46 localities.
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.
Antarctica | |
| Grew (1982) |
| Grew (1982) | |
| Grew (1982) | |
| Grew (1982) | |
| Grew (1982) |
| Grew (1982) | |
Canada | |
| Arima et al. (1991) |
| Berg et al. (1976) |
France | |
| [Barrier D et al. (2004) |
Germany | |
| Schreyer et al. (1986) |
| Schreyer et al. (1983) |
| Hentschel (1983) +1 other reference |
| Schreyer et al. (1983) |
| Leu (2017) |
| Schreyer et al. (1983) |
| Schreyer et al. (1983) | |
| Hentschel et al. (1977) +1 other reference |
| Blass et al. (2006) |
| Schäfer (1979) |
| Schüller (1990) |
| Borghini et al. (2024) |
| Witzke et al. (1998) |
Hungary | |
| GEODA 2007/1 |
India | |
| Waters (1991) |
Italy | |
| Balassone et al. (2008) |
| Parodi et al. (1989) |
| Parodi et al. (1989) | |
| Signoretti et al. (2004) +1 other reference | |
Japan | |
| Hiroaki Tano and Alfredo Petrov ... |
| Labels of several dealers at Tokyo show | |
| Kobayashi (1978) |
| Petrov (n.d.) |
| Yokomizo & Miyachi (1978) |
| Petrov (n.d.) |
New Zealand | |
| Grapes et al. (1993. Vug minerals in rhyolite, Hendersons Quarry, Mount Ngongotaha, Geological Society of New Zealand, Miscellaneous Publication 79A: 76.) |
Norway | |
| Maijer et al. (1977) |
| Waters (1991) +1 other reference |
Peru | |
| Liipo et al. (1994) |
Russia | |
| Seryotkin et al. (2008) |
| Bogdanova N.G. et al. (1980) |
South Africa | |
| Nowicki et al. (1995) +1 other reference |
Spain | |
| Fran Garcia alacid collection - EDX ... |
Uganda | |
| Waters (1991) |
UK | |
| Chinner et al. (1973) +2 other references |
USA | |
| Jerry Cone Collection |
| D.E. Russell Collection |




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The
Nickenicher Weinberg, Nickenich, Pellenz, Mayen-Koblenz, Rhineland-Palatinate, Germany