Tephroite
A valid IMA mineral species - grandfathered
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About Tephroite
Formula:
Mn2+2SiO4
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 τεφροζ "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
GUID
(UUID V4):
(UUID V4):
8891c9b3-1edc-45aa-a4d9-2d431d5be213
IMA Classification of Tephroite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Mn2+2(SiO4)
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 |
|---|---|---|
| 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 = 0.047
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Very High
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+2SiO4
Elements listed:
Common Impurities:
Fe,Zn,Ca,Mg
Crystallography of Tephroite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/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) |
|---|---|---|---|---|---|---|---|
| 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 |
| 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 |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 |
| 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 |
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-𝑇 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 this group:
| Calcio-olivine | Ca2SiO4 | Orth. mmm (2/m 2/m 2/m) |
| Fayalite | Fe2+2SiO4 | Orth. mmm (2/m 2/m 2/m) |
| Forsterite | Mg2SiO4 | Orth. mmm (2/m 2/m 2/m) |
| Glaucochroite | CaMn2+SiO4 | Orth. mmm (2/m 2/m 2/m) |
| Kirschsteinite | CaFe2+SiO4 | Orth. mmm (2/m 2/m 2/m) : Pnma |
| Laihunite | (Fe2+0.5◻0.5)Fe3+[SiO4] | Mon. 2/m : P21/b |
| Liebenbergite | Ni2SiO4 | Orth. mmm (2/m 2/m 2/m) |
| Monticellite | CaMgSiO4 | Orth. mmm (2/m 2/m 2/m) |
Forms a series with:
Common Associates
Associated Minerals Based on Photo Data:
| 120 photos of Tephroite associated with Willemite | Zn2SiO4 |
| 75 photos of Tephroite associated with Calcite | CaCO3 |
| 67 photos of Tephroite associated with Franklinite | Zn2+Fe3+2O4 |
| 58 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 |
| 18 photos of Tephroite associated with Rhodonite | CaMn3Mn[Si5O15] |
| 16 photos of Tephroite associated with Sonolite | Mn2+9(SiO4)4(OH)2 |
| 15 photos of Tephroite associated with Andradite | Ca3Fe3+2(SiO4)3 |
| 15 photos of Tephroite associated with Vittinkiite | MnMn3Mn[Si5O15] |
Related Minerals - Strunz-mindat Grouping
| 9.AC. | Ahrensite | SiFe2O4 |
| 9.AC. | Poirierite | Mg2SiO4 |
| 9.AC.05 | Fayalite | Fe2+2SiO4 |
| 9.AC.05 | Forsterite | Mg2SiO4 |
| 9.AC.05 | Glaucochroite | CaMn2+SiO4 |
| 9.AC.05 | Kirschsteinite | CaFe2+SiO4 |
| 9.AC.05 | Laihunite | (Fe2+0.5◻0.5)Fe3+[SiO4] |
| 9.AC.05 | Liebenbergite | Ni2SiO4 |
| 9.AC.10 | Monticellite | CaMgSiO4 |
| 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:
Localities for Tephroite
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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Sterling Mine, Sterling Hill, Ogdensburg, Sussex County, New Jersey, USA