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Obertiite Mineral Data
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General Obertiite Information
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 Chemical Formula: |
NaNa2(Mg3Fe+++Ti)Si8O22(O,F,OH)2 |
| Composition: |
Molecular Weight = 855.28 gm |
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Sodium 8.06 % Na 10.87 % Na2O |
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Magnesium 8.53 % Mg 14.14 % MgO |
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Titanium 5.60 % Ti 9.34 % TiO2 |
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Iron 6.53 % Fe 9.34 % Fe2O3 |
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Silicon 26.27 % Si 56.20 % SiO2 |
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Hydrogen 0.03 % H 0.26 % H2O |
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Oxygen 44.43 % O |
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Fluorine 0.56 % F 0.56 % F |
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- %
F -0.23 % -O=F2 |
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______ ______ |
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100.00 % 100.47 % = TOTAL OXIDE |
| Empirical Formula: |
Na3Mg3Fe3+Ti(Si8O22)O1.5F0.25(OH)0.25 |
| Environment: |
In cavities with basaltic flows. A member of the anhydrous amphibole group. |
| IMA Status: |
Approved IMA 1998 (Dana # Added) |
| Locality: |
The Bellerberg quarry, Laacher See district, Eifel region, Germany. Link to MinDat.org Location Data. |
| Name Origin: |
Named for Dr. Roberta Oberti (1951-), Pavia, Italy, for her contributions to the understanding of the crystal chemistry of the amphibole group. |
| Synonym: |
Ferric-nyboite |
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IMA1998-046 |
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Obertiite Image |
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Images:
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Obertiite Crystallography
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| Axial Ratios: |
a:b:c =0.5455:1:0.2953 |
| Cell Dimensions: |
a = 9.776, b = 17.919, c = 5.292, Z = 2; beta = 104.05° V = 899.30 Den(Calc)= 3.16 |
| Crystal System: |
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m |
| X Ray Diffraction: |
By Intensity(I/Io): 8.414(1)(110), 2.705(0.7)(331,151), 3.39(0.6)(131),2.531(0.5)(202), 3.117(0.5)(310), 4.467(0.5)(040), |
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Physical Properties of Obertiite
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| Cleavage: |
{110} Perfect, {110} Perfect |
| Color: |
Pale pink. |
| Diaphaneity: |
Transparent to Translucent |
| Fracture: |
Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments. |
| Habit: |
Aggregates - Made of numerous individual crystals or clusters. |
| Habit: |
Bladed - Aggregates of thin lath-like crystals (e.g. kyanite). |
| Hardness: |
5 - Apatite |
| Luster: |
Vitreous (Glassy) |
| Streak: |
white |
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Optical Properties of Obertiite
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| Gladstone-Dale: |
CI calc= 0.108 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2078,KC= 0.2331
Ncalc = 1.74 |
| Optical Data: |
Biaxial (-), a=1.643, b=1.657, g=1.67, bire=0.0270, 2V(Calc)=86, 2V(Meas)=81. Dispersion dispersion not observed. |
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Calculated Properties of Obertiite
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| Electron Density: |
Bulk Density (Electron Density)=3.11 gm/cc
note: Specific Gravity of Obertiite =3.16 gm/cc.
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| Fermion Index: |
Fermion Index = 0.02
Boson Index = 0.98 |
| Photoelectric: |
PEObertiite = 4.17 barns/electron
U=PEObertiite x rElectron Density= 12.98 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Obertiite is Not Radioactive |
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Obertiite Classification
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| Dana Class: |
66.01.03c.16 (66)Inosilicate Double-Width Unbranched Chains, W=2 |
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(66.01)with P=2 amphibole configuration |
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(66.01.03c)Group 4, the sodic amphiboles |
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66.01.03c.01 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.02 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.03 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.04 Magnesioriebeckite []Na2[(Mg,Fe)3Fe2]Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.05 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.06 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.07 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.08 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.09 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.09a Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m |
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66.01.03c.09b Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m |
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66.01.03c.10 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.11 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m |
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66.01.03c.11a Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m |
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66.01.03c.11b Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m |
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66.01.03c.11c Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m |
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66.01.03c.12 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m |
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66.01.03c.12a Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m |
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66.01.03c.12b Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m |
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66.01.03c.13 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m |
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66.01.03c.14 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m |
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66.01.03c.15 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m |
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66.01.03c.16 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m |
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66.01.03c.17 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m |
| Strunz Class: |
09.DE.25 09 - SILICATES (Germanates) |
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09.D - Inosilicates* Structural terminology according to Liebau (1985) |
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09.DE -Inosilicates with 2-periodic double chains, Si4O11; amphibole family |
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09.DE.25 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m |
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09.DE.25 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m |
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09.DE.25 Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m |
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09.DE.25 Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m |
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09.DE.25 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m |
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09.DE.25 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m |
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09.DE.25 Magnesioriebeckite []Na2[(Mg,Fe)3Fe2]Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m |
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09.DE.25 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m |
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09.DE.25 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m |
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09.DE.25 Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m |
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09.DE.25 Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m |
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09.DE.25 Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m |
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09.DE.25 Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m |
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09.DE.25 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m |
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Other Obertiite Information
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| References: |
NAME( MinRec, v 32, p 218) PHYS. PROP.(MinRec, v 32, p 218) OPTIC PROP.(MinRec, v 32, p 218) |
| See Also: |
Links to other databases for Obertiite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info
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Obertiite
NaNa2(Mg3Fe+++Ti)Si8O22(O,F,OH)2
Dana No: 66.01.03c.16 Strunz No: 09.DE.25
Locality:
Notes:
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