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Meionite
A valid IMA mineral species - grandfathered
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About Meionite
Formula:
Ca4Al6Si6O24CO3
Colour:
Colorless, white, grey, pink, violet, blue, yellow, orange-brown, brown
Lustre:
Vitreous, Resinous, Pearly
Hardness:
5 - 6
Specific Gravity:
2.74 - 2.78
Crystal System:
Tetragonal
Member of:
Name:
Named in 1801 by Rene Just Haüy from μειωυ Greek for less, in reference to the less acute pyramidal form as compared to vesuvianite.
Type Locality:
Visit gemdat.org for Unique Identifiers
Mindat ID:
2627
Long-form identifier:
mindat:1:1:2627:3
Similar Names
| Maenite | A rock subtype | |
| Mayenita | A synonym of Chlormayenite | |
| Melonite | A valid IMA mineral species - grandfathered | NiTe2 |
| Monite | A synonym of Hydroxylapatite | |
| Möhnite | A valid IMA mineral species | (NH4)K2Na(SO4)2 |
IMA Classification of Meionite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Ca4Al6Si6O24(CO3)
Classification of Meionite
9.FB.15
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
B : Tektosilicates with additional anions
17.4.6
17 : Silicates Containing other Anions
4 : Silicates with carbonates
17 : Silicates Containing other Anions
4 : Silicates with carbonates
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 |
|---|---|---|
| Me | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Mei | 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 |
| Me | 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 |
Physical Properties of Meionite
Vitreous, Resinous, Pearly
Transparency:
Transparent, Opaque
Colour:
Colorless, white, grey, pink, violet, blue, yellow, orange-brown, brown
Streak:
White
Hardness:
5 - 6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {100}{110}
Distinct on {100}{110}
Fracture:
Irregular/Uneven, Conchoidal
Density:
2.74 - 2.78 g/cm3 (Measured) 2.86 g/cm3 (Calculated)
Optical Data of Meionite
Type:
Uniaxial (-)
RI values:
nω = 1.59 - 1.6 nε = 1.556 - 1.562
Max. Birefringence:
δ = 0.034 - 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:
Moderate (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 Meionite
Mindat Formula:
Ca4Al6Si6O24CO3
Element Weights:
Common Impurities:
Mg,Na,K,Cl,H2O,S
Chemical Analysis
Oxide wt%:
| 1 | 2 | 3 | |
|---|---|---|---|
| SiO2 | 44.05 % | 50.14 % | 47.17 % |
| TiO2 | 0.01 % | 0.00 % | 0.03 % |
| Al2O3 | 28.67 % | 24.57 % | 26.29 % |
| Fe2O3 | 0.08 % | 0.03 % | 0.15 % |
| MnO | 0.01 % | 0.00 % | 0.01 % |
| MgO | 0.07 % | 0.06 % | 1.00 % |
| CaO | 18.55 % | 12.56 % | 14.31 % |
| Na2O | 2.55 % | 5.70 % | 3.82 % |
| K2O | 0.24 % | 0.93 % | 1.01 % |
| P2O5 | 0.01 % | ||
| H2O+ | 0.26 % | 0.07 % | 0.93 % |
| H2O- | 0.13 % | 0.22 % | 0.50 % |
| CO2 | 3.2 % | 3.04 % | 2.66 % |
| SrO | 0.19 % | 0.25 % | |
| BaO | |||
| SO3 | 1.63 % | 1.16 % | 1.42 % |
| Cl | 0.03 % | 1.52 % | 0.56 % |
| F | 0.00 % | 0.00 % | 0.04 % |
| Loss-O=Cl+F | -0.01 % | -0.34 % | -0.14 % |
| Total: | 99.66 % | 99.92 % | 99.76 % |
Empirical formulas:
| Sample ID | Empirical Formula |
|---|---|
| 1 | (Ca2.95Na0.74K0.05)3.74Al5.02Si6.55)O24[Cl0.01(CO3)0.66(SO4)0.16]0.83 corresponding to Mar33.8Me66.2 |
| 2 | (Na1.62Ca1.98K0.17)3.82Al4.25Si7.36)O24[Cl0.33(CO3)0.63(SO4)0.13]1.00 corresponding to Mar47.4Me52.6 |
| 3 | (Ca2.27Na1.10K0.19Mg0.22)3.78Al4.59Si6.98)O24[Cl0.11(CO3)0.53(SO4)0.14F0.01]0.79 corresponding to Mar40.7Me59.3 |
Sample references:
| ID | Locality | Reference | Notes |
|---|---|---|---|
| 1 | Slyudyanka, Slyudyansky District, Irkutsk Oblast, Russia | Wet chemical analysis of single meionite crystal with pyroxene inclusions | |
| 2 | Otter Lake, Pontiac RCM, Outaouais, Québec, Canada | Wet chemical analysis of meionite associated with augite, phlogopite and calcite. The specimen is labelled "Huddersfield township" | |
| 3 | " " | Wet chemical analysis of meionite associated with calcite, amphibole and diopside. Specimen is labelled "Huddersfield township" |
Crystallography of Meionite
Crystal System:
Tetragonal
Class (H-M):
4/m - Dipyramidal
Space Group:
I4/m
Cell Parameters:
a = 12.179(1) Å, c = 7.571(1) Å
Ratio:
a:c = 1 : 0.622
Unit Cell V:
1,122.99 ų (Calculated from Unit Cell)
Z:
2
Morphology:
Prismatic, granular, massive.
Comment:
On synthetic material. Teertstra & Sherriff (1996) give a = 12.20(1) and c = 7.556(5) Å for end-member meionite.
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) |
|---|---|---|---|---|---|---|---|
| 0006213 | Meionite | Antao S M, Hassan I, Wang J, Lee P L, Toby B H (2008) State-of-the-art high-resolution powder x-ray diffraction (HRPXRD) illustrated with Rietveld structure refinement of quartz, sodalite, tremolite, and meionite The Canadian Mineralogist 46 1501-1509 |  | 2008 | Slyudyanka, Siberia, Russia | 0 | 293 |
| 0015648 | Meionite | Lin S B, Burley B J (1974) The crystal structure of an intermediate scapolite - wernerite Tschermaks Mineralogische und Petrographische Mitteilungen 21 196-215 | 1974 | Tsarasaotra, Madagascar | 0 | 293 | |
| 0004640 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 298 | |
| 0004644 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 293 | |
| 0004641 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 299 | |
| 0004645 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 396 | |
| 0004643 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 196 | |
| 0004642 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 101 | |
| 0004646 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 494 | |
| 0004647 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 594 | |
| 0004648 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 694 | |
| 0004649 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 793 | |
| 0004650 | Meionite | Antao S M, Hassan I (2008) Unusual Al-Si ordering in calcic scapolite, Me79.6, with increasing temperature American Mineralogist 93 1470-1477 | | 2008 | 0 | 900 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
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Data courtesy of RRUFF project at University of Arizona, used with permission.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| 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 |
| 9 : Lava/xenolith minerals (hornfels, sanidinite facies) | |
| 10 : Basalt-hosted zeolite minerals | |
| Stage 3b: Earth’s earliest hydrosphere | >4.45 |
| 16 : Low-𝑇 aqueous alteration of Hadean subaerial lithologies (see also #23) | |
| Near-surface Processes | |
| 23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) | |
| 25 : Evaporites (prebiotic) | |
| High-𝑇 alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Geological Setting:
Metamorphosed rock.
Type Occurrence of Meionite
Synonyms of Meionite
Other Language Names for Meionite
Varieties of Meionite
| Algerite | Square unterminated prisms to several cm, rarely shows the normal pyramid. Varies from fresh to an altered meionite partly replaced by muscovite and possibly minor vesuvianite. |
| Kembleite | Slender pale yellow to brown elongated square prismatic crystals, often intergrown with fine-grained phlogopite. |
| Nuttallite | gray with slight tint of purple or blue, occasional slight chatoyancy. |
Relationship of Meionite to other Species
Member of:
Other Members of Scapolite Group:
| Marialite | Na4Al3Si9O24Cl | Tet. 4/m : I4/m |
| 'Scapolite' | This term generally refers to just the marialite-meionite series, not the full scapolite group, ... | Tet. |
| Silvialite | (Ca,Na)4(Al6Si6O24)(SO4,CO3) | Tet. 4/m : I4/m |
Common Associates
Associations Based on Photo Data:
| 55 photos of Meionite associated with Calcite | CaCO3 |
| 51 photos of Meionite associated with Diopside | CaMgSi2O6 |
| 31 photos of Meionite associated with Titanite | CaTiO(SiO4) |
| 16 photos of Meionite associated with Phlogopite | KMg3(AlSi3O10)(OH)2 |
| 13 photos of Meionite associated with Graphite | C |
| 12 photos of Meionite associated with Quartz | SiO2 |
| 12 photos of Meionite associated with Marialite | Na4Al3Si9O24Cl |
| 11 photos of Meionite associated with Spinel | MgAl2O4 |
| 10 photos of Meionite associated with Vesuvianite | Ca19Fe3+Al4(Al6Mg2)(◻4)◻[Si2O7]4[(SiO4)10]O(OH)9 |
Gem Scapolite occurrence, Soamatasy, Ihosy District, Ihorombe, Madagascar