Åkermanite
A valid IMA mineral species - grandfathered
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About Åkermanite
Anders Richard Åkerman (1837-1922)
Formula:
Ca2Mg[Si2O7]
Colour:
Colorless, yellowish gray, green, brown
Lustre:
Vitreous, Resinous
Hardness:
5 - 6
Specific Gravity:
2.944
Crystal System:
Tetragonal
Member of:
Name:
First described from samples of slags from furnace iron production found at three furnace localities: Hofors, Löfsjöen and Mölnbo, Sweden (Vogt 1884). Named by the Norwegian geologist, professor Johan Herman Lie Vogt (1858-1932) in honor of Anders Richard Åkerman (1837-1922), Swedish metallurgist. During his comprehensive study of the mineralogy of slag products, Vogt discovered a new Ca-Mg-silicate, and named the mineral Åkermanit. Åkerman had kindly given J.H.L. Vogt access to Stockholms Bergskolas large collection of slags. It was in samples from this collection Vogt discovered the mineral.
Name Encoding
ASCII-7:
Akermanite
Unique Identifiers
Mindat ID:
70
Long-form identifier:
mindat:1:1:70:9
IMA Classification of Åkermanite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca2MgSi2O7
Classification of Åkermanite
9.BB.10
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
55.4.1.1
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
4 : Si2O7 Groups, Generally with No Additional Anions with cations in [8] and lower coordination
55 : SOROSILICATES Si2O7 Groups,Generally with no Additional Anions
4 : Si2O7 Groups, Generally with No Additional Anions with cations in [8] and lower coordination
14.6.9
14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
14 : Silicates not Containing Aluminum
6 : Silicates of Ca with alkali or Mg or both
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 |
|---|---|---|
| Åk | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Ak | Kretz (1983) | Kretz, R. (1983) Symbols of rock-forming minerals. American Mineralogist, 68, 277–279. |
| Ak | Siivolam & Schmid (2007) | Siivolam, J. and Schmid, R. (2007) Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: List of mineral abbreviations. Web-version 01.02.07. IUGS Commission on the Systematics in Petrology. download |
| Ak | 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 |
| Ak | 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 Åkermanite
Vitreous, Resinous
Transparency:
Transparent, Translucent
Colour:
Colorless, yellowish gray, green, brown
Comment:
In thin section, colorless to yellow.
Streak:
White
Hardness:
5 - 6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {001} , poor on {110}
Distinct on {001} , poor on {110}
Fracture:
Irregular/Uneven, Conchoidal
Density:
2.944 g/cm3 (Measured) 2.922 g/cm3 (Calculated)
Optical Data of Åkermanite
Type:
Uniaxial (+)
RI values:
nω = 1.632 nε = 1.64
Max. Birefringence:
δ = 0.008
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:
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 uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
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.
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 Åkermanite
Mindat Formula:
Ca2Mg[Si2O7]
Element Weights:
Elements listed:
Crystallography of Åkermanite
Crystal System:
Tetragonal
Class (H-M):
42m - Scalenohedral
Space Group:
P421m
Cell Parameters:
a = 7.8288(8) Å, c = 5.0052(2) Å
Ratio:
a:c = 1 : 0.639
Unit Cell V:
306.77 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Crystals short prismatic to thin tabular, which may resemble squashed, octahedrally-modified cubes; granular, massive.
Twinning:
On {100} and 001 , cruciform.
Comment:
Synthetic material
Crystal Structure
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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) |
|---|---|---|---|---|---|---|---|
| M12011 | Åkermanite | Swainson, I.P., Dove, M.T., Schmahl, W.W., Putnis, A. (1992) Physics and Chemistry of Minerals 19, 185-195 Neutron powder diffraction study of the akermanite-gehlenite solid solution series | 1992 | Synthetic | 0 | 0 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.87 Å | (100) |
| 3.09 Å | (30) |
| 1.764 Å | (30) |
| 2.039 Å | (20) |
| 2.488 Å | (18) |
| 3.73 Å | (14) |
| 5.55 Å | (12) |
Comments:
Synthetic.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 1: Primary nebular phases | 4.567-4.561 |
| 3 : Solar nebular condensates (CAIs, AOAs, URIs) | >4.565 |
| Stage 2: Planetesimal differentiation and alteration | 4.566-4.550 |
| 6 : Secondary asteroid phases | 4.566-4.560 |
| Stage 3a: Earth’s earliest Hadean crust | >4.50 |
| 8 : Mafic igneous rocks | |
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 35 : Ultra-alkali and agpaitic igneous rocks | |
| 36 : Carbonatites, kimberlites, and related igneous rocks | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
Geological Setting:
A product of contact metamorphism of siliceous limestones and dolostones, and in rocks of the sanidinite facies. Also forms from alkalic magmas rich in calcium.
Synonyms of Åkermanite
Other Language Names for Åkermanite
Dutch:Åkermaniet
French:Åkermanite
German:Åkermanit
Oakermanit
Okermanit
Oakermanit
Okermanit
Norwegian:Åkermanitt
Russian:Окерманит
Simplified Chinese:镁黄长石
Spanish:Åkermanita
Oakermanita
Okermanita
Oakermanita
Okermanita
Varieties of Åkermanite
| Justite (of Hofmann-Degen) | An artificial (anthropogenic) mineral found as crystals in lead furnaces in Clausthal, Harz, Germany. An Fe(II)- and Zn-bearing (ferroan-zincian) åkermanite. |
Relationship of Åkermanite to other Species
Member of:
Other Members of Melilite Group:
| Alumoåkermanite | (CaNa)Al[Si2O7] | Tet. 42m : P421m |
| Bennesherite | Ba2Fe2+[Si2O7] | Tet. 42m : P421m |
| 'Ferri-gehlenite' | Ca2Fe3+[AlSiO7] | |
| Ferroåkermanite | Ca2Fe[Si2O7] | Tet. 42m : P421m |
| Gehlenite | Ca2Al[AlSiO7] | Tet. 42m : P421m |
| Gugiaite | Ca2Be[Si2O7] | Tet. 42m : P42m |
| Hardystonite | Ca2Zn[Si2O7] | Tet. 42m : P421m |
| Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] | Tet. 42m : P421m |
| Okayamalite | Ca2B[BSiO7] | Tet. 42m : P421m |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 9 photos of Åkermanite associated with Kalsilite | KAlSiO4 |
| 3 photos of Åkermanite associated with Fluorapatite | Ca5(PO4)3F |
| 2 photos of Åkermanite associated with Saponite | Ca0.25(Mg,Fe)3((Si,Al)4O10)(OH)2 · nH2O |
| 1 photo of Åkermanite associated with Cuprite | Cu2O |
| 1 photo of Åkermanite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 1 photo of Åkermanite associated with Dolomite | CaMg(CO3)2 |
| 1 photo of Åkermanite associated with Kottenheimite | Ca 3Si(SO4)2(OH)6 · 12H2O |
| 1 photo of Åkermanite associated with Ettringite | Ca6Al2(SO4)3(OH)12 · 26H2O |
| 1 photo of Åkermanite associated with Linarite | PbCu(SO4)(OH)2 |
| 1 photo of Åkermanite associated with Gismondine Subgroup |
Related Minerals - Strunz-mindat Grouping
| 9.BB.10 | Hardystonite | Ca2Zn[Si2O7] |
| 9.BB.10 | Okayamalite | Ca2B[BSiO7] |
| 9.BB.10 | Jeffreyite | (Ca,Na)2(Be,Al)(Si2O7,HSi2O7) |
| 9.BB.10 | Alumoåkermanite | (CaNa)Al[Si2O7] |
| 9.BB.10 | 'Ferri-gehlenite' | Ca2Fe3+[AlSiO7] |
| 9.BB.10 | Gehlenite | Ca2Al[AlSiO7] |
| 9.BB.10 | Ferroåkermanite | Ca2Fe[Si2O7] |
| 9.BB.10 | Cebollite | Ca5Al2(SiO4)3(OH)4 |
| 9.BB.10 | Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] |
| 9.BB.10 | Gugiaite | Ca2Be[Si2O7] |
| 9.BB.15 | Barylite | Be2Ba(Si2O7) |
| 9.BB.15 | 'Barylite-1O' | Be2Ba(Si2O7) |
| 9.BB.20 | Bennesherite | Ba2Fe2+[Si2O7] |
| 9.BB.20 | Andrémeyerite | BaFe2+2(Si2O7) |
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.
Åkermanite in petrology
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Internet Links for Åkermanite
mindat.org URL:
https://www.mindat.org/min-70.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 Åkermanite
Reference List:
Osborn, E. F., Schairer, J. F. (1941) The ternary system pseudowollastonite-akermanite-gehlenite. American Journal of Science, 239 (10) 715-763 doi:10.2475/ajs.239.10.715
Schairer, J. F., Bowen, N. L. (1942) The binary system CaSiO3-diopside, and the relations between CaSiO3 and akermanite. American Journal of Science, 240 (10). 725-742 doi:10.2475/ajs.240.10.725
Neuvonen, K.J. (1952) Thermochemical investigation of the åkermanite-gehlenite series. Bulletin de la Commission Géologique de Finlande Vol. 158. Geological Survey of Finland
Harker, R. I.; Tuttle, O. F. (1956) The lower limit of stability of akermanite (Ca2MgSi2O7). American Journal of Science, 254 (8). 468-478 doi:10.2475/ajs.254.8.468
Christie, O.H.J. (1962) On sub solidus relations of silicates. IV. The systems åkermanite - sodium-gehlenite and gehlenite - sodium gehlenite. Norsk Geologisk Tidsskrift [Norwegian Journal of Geology], 42 (1-2). 31-44
Dear, P.S (1970) Isomorphism of åkermanite and strontio-gehlenite. Lithos, 3 (1) 13-16 doi:10.1016/0024-4937(70)90083-6
Christiaan de Wys, E. (1972) Additional data concerning the stability of åkermanite. Mineralogical Magazine, 38 (297) 635-636 doi:10.1180/minmag.1972.038.297.18
Charlu, T.V., Newton, R.C., Kleppa, O.J. (1981) Thermochemistry of synthetic Ca2Al2SiO7 (gehlenite)-Ca2MgSi2O7 (åkermanite) melilites. Geochimica et Cosmochimica Acta, 45 (9) 1609-1617 doi:10.1016/0016-7037(81)90289-1
ONUMA, KOSUKE, MORIDAIRA, HIDEYA (1991) The system diopside-akermanite-gehlenite at 1 atm. Journal of Mineralogy, Petrology and Economic Geology, 86 (12) 554-559 doi:10.2465/ganko.86.554
Swainson, Ian P., Dove, Martin T., Schmahl, Wolfgang W., Putnis, Andrew (1992) Neutron powder diffraction study of the åkermanite-gehlenite solid solution series. Physics and Chemistry of Minerals, 19 (3). 185-195 doi:10.1007/bf00202107
Kakitani, Satoru; Ishii, Hiroshi; Yamaguchi, Kazuhiro (1997) Synthesis of Solid Solutions Based on the Akermanite and/or Hardystonite Systems and Their Fluorescence Properties. Japanese Journal of Applied Physics, 36. 6793-6797 doi:10.1143/jjap.36.6793
KUSAKA, Katsuhiro, OHMASA, Masaaki, HAGIYA, Kenji, IISHI, Kazuaki, HAGA, Nobuhiko (1998) On variety of the Ca coordination in the incommensurate structure of synthetic iron-bearing åkermanite, Ca2(Mg0.55,Fe0.45)Si2O7. Mineralogical Journal, 20 (2). 47-58 doi:10.2465/minerj.20.47
Courtial, P., Téqui, C., Richet, P. (2000) Thermodynamics of diopside, anorthite, pseudowollastonite, CaMgGeO4 olivine, and åkermanite up to near the melting point. Physics and Chemistry of Minerals, 27 (4). 242-250 doi:10.1007/s002690050253
Bindi, Luca, Bonazzi, Paola, Dušek, Michal, Petříček, Václav, Chapuis, Gervais (2001) Five-dimensional structure refinement of natural melilite, (Ca1.89Sr0.01Na0.08K0.02)(Mg0.92Al0.08)(Si1.98Al0.02)O7. Acta Crystallographica Section B Structural Science, 57 (6) 739-746 doi:10.1107/s0108768101014495
Bindi, Luca, Rees, Leigh H., Bonazzi, Paola (2003) Twinning in natural melilite simulating a fivefold superstructure. Acta Crystallographica Section B Structural Science, 59 (1) 156-158 doi:10.1107/s0108768103000041
Haussühl, S.; Liebertz, J. (2004) Elastic and thermoelastic properties of synthetic Ca2MgSi2O7 (åkermanite) and Ca2ZnSi2O7 (hardystonite). Physics and Chemistry of Minerals, 31 (8). 565-567 doi:10.1007/s00269-004-0416-9
Gemmi, M., Merlini, M., Cruciani, G., Artioli, G. (2007) Non-ideality and defectivity of the åkermanite-gehlenite solid solution: An X-ray diffraction and TEM study. American Mineralogist, 92 (10). 1685-1694 doi:10.2138/am.2007.2380
Localities for Åkermanite
Showing 75 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.
Atlantic Ocean | |
| Gablina et al. (2018) |
| Gablina et al. (2018) | |
Austria | |
| Kolitsch (2013) |
Canada | |
| OWENS et al. (2010) |
| Owens (2000) | |
| Sabina (1968) |
| Mineralogical Society of America - ... | |
| Sabina (1968) |
China | |
| Xiyue Wang et al. (1987) |
Czech Republic | |
| Pauliš P. Mineralogické lokality ... |
| Jirasek et al. (2026) |
| Žáček et al. (2005) |
DR Congo | |
| Andersen et al. (2014) |
France | |
| Vanaecker et al. (2014) |
| publication date: November 2018 +1 other reference |
| Vanaecker et al. (2014) |
Germany | |
| Keller et al. (1995) |
| Hofmann-Degen (1919) |
| [var: Justite (of Hofmann-Degen)] Neschen (n.d.) +1 other reference | |
| |
| Bender et al. (1994) +1 other reference |
| Blaß et al. (1995) |
| Luetcke (n.d.) +1 other reference | |
| Neschen (n.d.) |
| Christof Schäfer |
| in the collection of Christof Schäfer | |
| Skrzyńska et al. (2023) | |
| Juroszek et al. (Ti 5 Fe) +1 other reference | |
| Blaß et al. (1999) |
| in the collection of Christof Schäfer | |
| Aksenov et al. (2014) |
| in the collection of Christof Schäfer +2 other references |
| Gerhard Möhn Collection Analyzed by ... |
Iraq | |
| |
Israel | |
| Galuskina et al. (2024) |
| Galuskina et al. (2024) | |
Italy | |
| [Lapis 1994:5 p.13-23 |
| |
| Vanrusselt (2023) |
| Stoppa et al. (2009) |
| Joel Dyer collection |
Japan | |
| The Mineral Species of Japan (5th ed) |
Middle East | |
| Gross (1977) | |
Mongolia | |
| Peretyazhko et al. (2017) |
Morocco | |
| Berger et al. (2009) | |
Namibia | |
| Ettler et al. (2009) |
Norway | |
| Jamtveit et al. (1997) |
Poland | |
| Vanaecker et al. (2014) |
Romania | |
| Szakáll |
| Szakáll et al. (2010) | |
Russia | |
| Sokol et al. (2019) +1 other reference |
| Pavel M. Kartashov (n.d.) |
| ... |
| Kalinkina et al. (2001) |
| Arzamastsev et al. (1990) +2 other references | |
| Sklyarov et al. (2021) | |
Slovakia | |
| Reato et al. (2022) |
| Martin Števko-unpublished |
South Africa | |
| Cairncross et al. (1995) |
| Pohl et al. (1991) |
Sweden | |
| Sandström et al. (2010) |
UK | |
| S. Rust collection |
| Sabine et al. (1985) |
| Tilley et al. (1931) | |
| Tindle (2008) | |
| Agrell (1965) +2 other references |
USA | |
| Mineralogical Society of America - ... |
| Eckel et al. (1997) |
| Mineralogical Society of America - ... |
| Mineralogical Society of America - ... |
| Valley et al. (1979) +1 other reference |
| Daniel Hummer Collection |
| Smith (1991) |
Outer Space | |
| Posch et al. (2007) |
Quick NavTopAbout ÅkermaniteName EncodingUnique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentSynonymsOther LanguagesVarietiesRelationshipsCommon AssociatesStrunz-MindatOther InformationÅkermanite in petrologyInternet Links References Localities Locality List
Graulay quarry, Hillesheim, Gerolstein, Vulkaneifel, Rhineland-Palatinate, Germany