Tephroite
A valid IMA mineral species - grandfathered
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About Tephroite
Formula:
Mn2+2(SiO4)
Colour:
Grey, olive-green, flesh red or reddish-brown, dark brown.
Lustre:
Vitreous, Greasy
Hardness:
6
Specific Gravity:
3.87 - 4.12
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1823 by Johann Friedrich August Breithaupt from Greek τεφρος "tephros" = ash-colored, alluding to the usual gray color of the mineral.
Olivine Group. Fayalite-Tephroite Series, and the Forsterite-Tephroite Series. The Mn2+ analogue of Fayalite, Forsterite, and Calcio-Olivine.
Unique Identifiers
Mindat ID:
3913
Long-form identifier:
mindat:1:1:3913:6
Similar Names
| Deveroite-(Ce) | A valid IMA mineral species | Ce2(C2O4)3 · 10H2O |
| Tephrite | A rock classification type |
IMA Classification of Tephroite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mn2+2SiO4
First published:
1823
Classification of Tephroite
9.AC.05
9 : SILICATES (Germanates)
A : Nesosilicates
C : Nesosilicates without additional anions; cations in octahedral [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
C : Nesosilicates without additional anions; cations in octahedral [6] coordination
Dana 7th ed.:
51.3.1.4
51.3.1.4
51 : NESOSILICATES Insular SiO4 Groups Only
3 : Insular SiO4 Groups Only with all cations in octahedral [6] coordination
51 : NESOSILICATES Insular SiO4 Groups Only
3 : Insular SiO4 Groups Only with all cations in octahedral [6] coordination
14.17.2
14 : Silicates not Containing Aluminum
17 : Silicates of Mn
14 : Silicates not Containing Aluminum
17 : Silicates of Mn
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 |
|---|---|---|
| Tep | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Tep | 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 |
| Tep | 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 Tephroite
Vitreous, Greasy
Transparency:
Transparent, Translucent
Colour:
Grey, olive-green, flesh red or reddish-brown, dark brown.
Streak:
Pale gray
Hardness:
6 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Distinct on {010}
Imperfect on {001}
Distinct on {010}
Imperfect on {001}
Fracture:
Irregular/Uneven, Conchoidal
Density:
3.87 - 4.12 g/cm3 (Measured) 4.15 g/cm3 (Calculated)
Optical Data of Tephroite
Type:
Biaxial (-)
RI values:
nα = 1.770 - 1.788 nβ = 1.807 - 1.810 nγ = 1.817 - 1.825
2V:
Measured: 60° to 70°, Calculated: 78°
Max. Birefringence:
δ = 0.037 - 0.047
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:
Very 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 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.
Dispersion:
r > v
Optical Extinction:
X = b; Y = c; Z = a.
Pleochroism:
Weak
Comments:
X= brownish red
Y= reddish
Z= greenish blue
Y= reddish
Z= greenish blue
Chemistry of Tephroite
Mindat Formula:
Mn2+2(SiO4)
Element Weights:
Elements listed:
Common Impurities:
Fe,Zn,Ca,Mg
Crystallography of Tephroite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pnma
Cell Parameters:
a = 4.88(2) Å, b = 10.61(2) Å, c = 6.24(2) Å
Ratio:
a:b:c = 0.46 : 1 : 0.588
Unit Cell V:
323.09 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Short prismatic
Twinning:
Uncommon {011}
Comment:
Space group Pbnm (non-standard setting).
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) |
|---|---|---|---|---|---|---|---|
| 0019693 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019692 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019691 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019690 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019689 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019687 | Tephroite | Yamazaki S, Toraya H (1999) Rietveld refinement of site-occupancy parameters of Mg2-xMnxSiO4 using a new weight function in least-squares fitting Journal of Applied Crystallography 32 51-59 | 1999 | synthetic | 0 | 293 | |
| 0019697 | Tephroite | Redfern S A T, Knight K S, Henderson C M B, Wood B J (1998) Fe-Mn cation ordering in fayalite-tephroite (FexMn1-x)2SiO4 olivines: A neutron diffraction study Mineralogical Magazine 62 607-615 |  | 1998 | synthetic | 0 | 293 |
| 0019696 | Tephroite | Redfern S A T, Knight K S, Henderson C M B, Wood B J (1998) Fe-Mn cation ordering in fayalite-tephroite (FexMn1-x)2SiO4 olivines: A neutron diffraction study Mineralogical Magazine 62 607-615 | | 1998 | synthetic | 0 | 293 |
| 0019695 | Tephroite | Fujino K, Sasaki S, Takeuchi Y, Sadanaga R (1981) X-ray determination of electron distributions in forsterite, fayalite and tephroite Acta Crystallographica B37 513-518 |  | 1981 | synthetic | 0 | 293 |
| 0000802 | Tephroite | Francis C A, Ribbe P H (1980) The forsterite-tephroite series: I. Crystal structure refinements American Mineralogist 65 1263-1269 | | 1980 | Madagascar | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.22 Å | (5) |
| 3.99 Å | (15) |
| 3.80 Å | (5) |
| 3.57 Å | (80) |
| 3.09 Å | (20) |
| 2.84 Å | (90) |
| 2.67 Å | (5) |
| 2.58 Å | (100) |
| 2.53 Å | (90) |
| 2.41 Å | (15) |
| 2.33 Å | (15) |
| 2.31 Å | (15) |
| 2.17 Å | (5) |
| 2.09 Å | (5) |
| 1.94 Å | (5) |
| 1.87 Å | (5) |
| 1.84 Å | (5) |
| 1.79 Å | (80) |
| 1.72 Å | (10) |
| 1.69 Å | (10) |
| 1.67 Å | (15) |
| 1.64 Å | (5) |
| 1.63 Å | (5) |
| 1.60 Å | (5) |
| 1.55 Å | (50) |
| 1.53 Å | (50) |
| 1.47 Å | (5) |
| 1.44 Å | (5) |
| 1.43 Å | (5) |
| 1.41 Å | (5) |
| 1.38 Å | (15) |
Comments:
ICDD 31-823 magnesian tephroite, ICDD 35-748 tephroite (synthetic)
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations | |
| 32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits | |
| Stage 5: Initiation of plate tectonics | <3.5-2.5 |
| 40 : Regional metamorphism (greenschist, amphibolite, granulite facies) |
Geological Setting:
In Fe-Mn ore deposits, skarns, and metamorphosed manganese rich sediments.
Type Occurrence of Tephroite
Place of Conservation of Type Material:
Mining Academy, Freiberg, Germany, 23653.
Associated Minerals at Type Locality:
Synonyms of Tephroite
Other Language Names for Tephroite
Varieties of Tephroite
| Magnesium-bearing tephroite | |
| Picrotephroite | Tephroite with MgO content up to 18.11 mas.% (in samples from Pajsberg, Sweden). |
Relationship of Tephroite to other Species
Member of:
Other Members of Olivine Group:
| Calcio-olivine | Ca2SiO4 | Orth. mmm(2/m2/m2/m) |
| Fayalite | Fe2+2(SiO4) | Orth. mmm(2/m2/m2/m) |
| Forsterite | Mg2(SiO4) | Orth. mmm(2/m2/m2/m) |
| Glaucochroite | CaMn2+(SiO4) | Orth. mmm(2/m2/m2/m) |
| Hinokageite | MnMg(SiO4) | Orth. mm2 |
| Kirschsteinite | CaFe2+(SiO4) | Orth. mmm(2/m2/m2/m) : Pnma |
| Laihunite | (Fe3+,Fe2+,◻)2(SiO4) | Mon. 2/m : P21/b |
| Liebenbergite | Ni2(SiO4) | Orth. mmm(2/m2/m2/m) |
| Monticellite | CaMg(SiO4) | Orth. mmm(2/m2/m2/m) |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 131 photos of Tephroite associated with Willemite | Zn2SiO4 |
| 86 photos of Tephroite associated with Calcite | CaCO3 |
| 76 photos of Tephroite associated with Franklinite | Zn2+Fe3+2O4 |
| 65 photos of Tephroite associated with Zincite | ZnO |
| 29 photos of Tephroite associated with Rhodochrosite | MnCO3 |
| 23 photos of Tephroite associated with Spessartine | Mn2+3Al2(SiO4)3 |
| 21 photos of Tephroite associated with Rhodonite | CaMn3Mn[Si5O15] |
| 20 photos of Tephroite associated with Sonolite | Mn2+9(SiO4)4(OH)2 |
| 15 photos of Tephroite associated with Vittinkiite | MnMn3Mn[Si5O15] |
| 15 photos of Tephroite associated with Andradite | Ca3Fe3+2(SiO4)3 |
Related Minerals - Strunz-mindat Grouping
| 9.AC. | Poirierite | Mg2SiO4 |
| 9.AC. | Ahrensite | SiFe2O4 |
| 9.AC.05 | Laihunite | (Fe3+,Fe2+,◻)2(SiO4) |
| 9.AC.05 | Forsterite | Mg2(SiO4) |
| 9.AC.05 | Hinokageite | MnMg(SiO4) |
| 9.AC.05 | Liebenbergite | Ni2(SiO4) |
| 9.AC.05 | Kirschsteinite | CaFe2+(SiO4) |
| 9.AC.05 | Glaucochroite | CaMn2+(SiO4) |
| 9.AC.05 | Fayalite | Fe2+2(SiO4) |
| 9.AC.10 | Monticellite | CaMg(SiO4) |
| 9.AC.15 | Brunogeierite | Ge4+Fe2+2O4 |
| 9.AC.15 | Ringwoodite | (Mg,Fe2+)2SiO4 |
| 9.AC.20 | Chesnokovite | Na2[SiO2(OH)2] · 8H2O |
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.
Tephroite in petrology
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Internet Links for Tephroite
mindat.org URL:
https://www.mindat.org/min-3913.html
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References for Tephroite
Reference List:
Peters, Tjerk, Schwander, Hans, Trommsdorff, Volkmar (1973) Assemblages among tephroite, pyroxmangite, rhodochrosite, quartz: Experimental data and occurrences in the Rhetic Alps. Contributions to Mineralogy and Petrology, 42 (4) 325-332 doi:10.1007/bf00372610
Finch, C.B., Clark, G.W., Kopp, O.C. (1975) Growth of single-crystal Mn2SiO4 (tephroite) by Czochralski and edge-defined film-fed (EFG) techniques. Journal of Crystal Growth, 29 (3). 269-272 doi:10.1016/0022-0248(75)90170-0
Takei, Humihiko (1976) Czochralski growth of Mn2SiO4 (tephroite) single crystal and its properties. Journal of Crystal Growth, 34 (1). 125-131 doi:10.1016/0022-0248(76)90270-0
Stidham, H. D., Bates, J. B., Finch, C. B. (1976) Vibrational spectra of synthetic single crystal tephroite, Mn2SiO4. The Journal of Physical Chemistry, 80 (11). 1226-1234 doi:10.1021/j100552a023
Okajima, Shinichi, Suzuki, Isao, Seya, Kiyoshi, Sumino, Yoshio (1978) Thermal expansion of single-crystal tephroite. Physics and Chemistry of Minerals, 3 (2) 111-115 doi:10.1007/bf00308115
Francis, Carl A., Ribbe, Paul H. (1980) The forsterite-tephroite series: I. Crystal structure refinements. American Mineralogist, 65 (11-12) 1263-1269
Fujino, K., Sasaki, S., Takéuchi, Y., Sadanaga, R. (1981) X-ray determination of electron distributions in forsterite, fayalite and tephroite. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 37 (3) 513-518 doi:10.1107/s0567740881003506
Francis, Carl A. (1985) New data on the forsterite-tephroite series. American Mineralogist, 70 (5-6) 568-575
Shannon, R.D.; Subramanian, M.A.; Hosoya, S.; Rossman, G.R. (1991) Dielectric constants of tephroite, fayalite and olivine and the oxide additivity rule. Physics and Chemistry of Minerals, 18 (1). 1-6 doi:10.1007/bf00199037
Redfern, S. A. T., Knight, K. S., Henderson, C. M. B., Wood, B. J. (1998) Fe-Mn cation ordering in fayalite–tephroite (FexMn1−x)2SiO4 olivines: a neutron diffraction study. Mineralogical Magazine, 62 (5) 607-615 doi:10.1180/002646198548007
Stüber, Christoph, Laqua, Wolfgang (1998) Point Defects of Tephroite. I: The Electrical Conductivity of Mn2SiO4. Zeitschrift für Physikalische Chemie, 206. 197-218 doi:10.1524/zpch.1998.206.part_1_2.197
Yamazaki, S.; Toraya, H. (1999) Rietveld refinement of site-occupancy parameters of Mg2−xMnxSiO4 using a new weight function in least-squares fitting. Journal of Applied Crystallography, 32 (1). 51-59 doi:10.1107/s0021889898010206
Localities for Tephroite
Showing 303 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.
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Čierna baňa, Čučma, Rožňava District, Košice Region, Slovakia