Tephroite Mineral Data (original) (raw)
General Tephroite Information
Mn2SiO4
Molecular Weight = 201.96 gm
Manganese 54.41 % Mn 70.25 % MnO
Silicon 13.91 % Si 29.75 % SiO2
Oxygen 31.69 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Mn2+2(SiO4)
Contact metamorphism of manganese bearing rocks.
Valid Species (Pre-IMA) 1823
Franklin and Sparta, New Jersey, USA. Link to MinDat.org Location Data.
From the Greek tephros - "ash gray" for its color.
ICSD 100433
PDF 35-748
Tephroite Image
Tephroite Comments: Sharp crystals of tephroite to 1.2 cm across. Location: N'Chwaning Mine, Kalahari Manganese Field, Northern Cape Province, South Africa.Scale: Picture size 5 cm. © John Veevaert |
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Tephroite Crystallography
a:b:c =0.4666:1:0.5862
a = 4.76, b = 10.2, c = 5.98, Z = 4; V = 290.34 Den(Calc)= 4.62
Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P nma
By Intensity(I/Io): 2.56(1), 2.86(0.85), 3.61(0.85),
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| | Francis C A , Ribbe P H , American Mineralogist , 65 (1980) p.1263-1269, The forsterite-tephroite series: I. Crystal structure refinements, Te 91, olivine | | ------------------------------------------------------------------------------------------------------------------------------------------------------------- |
Physical Properties of Tephroite
{010} Indistinct
Gray, Olive green, Bluish green, Red, Reddish brown.
4.11 - 4.39, Average = 4.25
Transparent to translucent
Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Massive - Granular - Common texture observed in granite and other igneous rock.
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
6.5 - Pyrite
Non-fluorescent.
Vitreous - Greasy
Nonmagnetic
gray
Optical Properties of Tephroite
CI meas= 0.054 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.13 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1743,KPDmeas= 0.1895,KC= 0.2003
Ncalc = 1.82 - 1.93
Biaxial (+), a=1.759, b=1.797, g=1.86, bire=0.1010, 2V(Calc)=78, 2V(Meas)=60-70. Dispersion none.
pale amber.
orange yellow.
Calculated Properties of Tephroite
Bulk Density (Electron Density)=4.04 gm/cc
note: Specific Gravity of Tephroite =4.25 gm/cc.
Fermion Index = 0.0066464499
Boson Index = 0.9933535501
PETephroite = 14.67 barns/electron
U=PETephroite x rElectron Density= 59.28 barns/cc.
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Tephroite is Not Radioactive
Tephroite Classification
51.03.01.04 (51)Nesosilicate Insular SiO4 Groups Only
(51.03)with all cations in octahedral [6] coordination
(51.03.01)Olivine group
51.03.01.00 Olivine* (Mg,Fe)2SiO4 Pbnm 2/m 2/m 2/m
51.03.01.01 Fayalite Fe2SiO4 Pbnm 2/m 2/m 2/m
51.03.01.02 Forsterite Mg2SiO4 Pbnm 2/m 2/m 2/m
51.03.01.03 Liebenbergite (Ni,Mg)2SiO4 Pbnm 2/m 2/m 2/m
51.03.01.04 Tephroite Mn2SiO4 P nma 2/m 2/m 2/m
51.03.01.05 Laihunite FeFe2(SiO4)2 P 21/b 2/m
09.AC.05 09 - SILICATES (Germanates)
09.A - Nesosilicates
09.AC -Nesosilicates without additional anions;
09.AC.05 Forsterite Mg2SiO4 Pbnm 2/m 2/m 2/m
09.AC.05 Glaucochroite CaMnSiO4 Pbnm 2/m 2/m 2/m
09.AC.05 Fayalite Fe2SiO4 Pbnm 2/m 2/m 2/m
09.AC.05 Olivine* (Mg,Fe)2SiO4 Pbnm 2/m 2/m 2/m
09.AC.05 Kirschsteinite CaFeSiO4 Pbmn 2/m 2/m 2/m
09.AC.05 Laihunite FeFe2(SiO4)2 P 21/b 2/m
09.AC.05 Liebenbergite (Ni,Mg)2SiO4 Pbnm 2/m 2/m 2/m
09.AC.05 Tephroite Mn2SiO4 P nma 2/m 2/m 2/m
Other Tephroite Information
Links to other databases for Tephroite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - CalTech Mineral Spectroscopy
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - Franklin Minerals(Palache)
9 - GeoScienceWorld
10 - Google Images
11 - Google Scholar
12 - Handbook of Mineralogy (MinSocAm)
13 - Handbook of Mineralogy (UofA)
14 - MinDAT
15 - Mineral and Gemstone Kingdom
16 - Mineralienatlas (Deutsch)
17 - Online Mineral Museum
18 - QUT Mineral Atlas
19 - Ruff.Info
20 - Scandinavian mineral gallery
21 - University of Colorado - Mineral Structure Data
22 - WWW-MINCRYST
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Ask about Tephroite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Espa�ol
Print or Cut-and-Paste your Tephroite Specimen Label here :
Tephroite
Mn2SiO4
Dana No: 51.03.01.04 Strunz No: 09.AC.05
Locality:
Notes: