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Oftedalite Mineral Data
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General Oftedalite Information
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Chemical Formula: |
(Sc,Ca)2KBe3Si12O30 |
Composition: |
Molecular Weight = 973.03 gm |
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Potassium 3.94 % K 4.74 % K2O |
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Calcium 3.25 % Ca 4.55 % CaO |
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Yttrium 0.27 % Y 0.35 % Y2O3 |
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Scandium 4.44 % Sc 6.80 % Sc2O3 |
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Manganese 1.02 % Mn 1.31 % MnO |
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Beryllium 2.70 % Be 7.48 % BeO |
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Aluminum 0.25 % Al 0.47 % Al2O3 |
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Iron 0.23 % Fe 0.30 % FeO |
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Silicon 34.58 % Si 73.98 % SiO2 |
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Oxygen 49.33 % O |
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______ ______ |
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100.00 % 99.98 % = TOTAL OXIDE |
Empirical Formula: |
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Environment: |
Occurs intergrown with Sc-rich milarite in the Heftetjern pegmatite. Milarite group |
IMA Status: |
Approved IMA 2004 (Dana # Added) |
Locality: |
Heftetjern pegmatite, about 4.3 km NW of T�rdal, Telemark county, southern Norway. Link to MinDat.org Location Data. |
Name Origin: |
Named for Ivar Oftedal (1894-1976), former Professor of Mineralogy at the Institute of Geology, University of Oslo, Norway. |
Synonym: |
IMA2003-045a |
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Oftedalite Crystallography
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Axial Ratios: |
a:c = 1:1.38565 |
Cell Dimensions: |
a = 10.097, c = 13.991, Z = 2; V = 1,235.28 Den(Calc)= 2.62 |
Crystal System: |
Hexagonal - Dihexagonal Dipyramidal H-M Symbol (6/m 2/m 2/m) Space Group: P 6/mmc |
X Ray Diffraction: |
By Intensity(I/Io): 3.229(1)(104), 2.88(0.8)(114), 4.097(0.7)(112),3.504(0.5)(004), 5.044(0.5)(110), 7.012(0.4)(002), 1.836(0.4)(412), 1.995(0.3)(314), 2.735(0.3)(204), |
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Physical Properties of Oftedalite
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Cleavage: |
{hk0} Poor |
Color: |
Grayish white. |
Diaphaneity: |
Transparent |
Fracture: |
Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments. |
Habit: |
Hexagonal - Six-sided crystal shape in cross-section or habit. |
Habit: |
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline). |
Hardness: |
6 - Orthoclase |
Luster: |
Vitreous (Glassy) |
Streak: |
colorless |
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Optical Properties of Oftedalite
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Gladstone-Dale: |
CI calc= 0.006 (Superior) - where the CI = (1-KPDcalc/KC) KPDcalc= 0.2116,KC= 0.2129 Ncalc = 1.56 |
Optical Data: |
Uniaxial (-), e=1.553, w=1.556, bire=0.0030. |
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Calculated Properties of Oftedalite
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Electron Density: |
Bulk Density (Electron Density)=2.59 gm/cc note: Specific Gravity of Oftedalite =2.62 gm/cc. |
Fermion Index: |
Fermion Index = 0.04 Boson Index = 0.96 |
Photoelectric: |
PEOftedalite = 3.42 barns/electron U=PEOftedalite x relectron= 8.88 barns/cc. |
Radioactivity: |
GRapi = 56.26 (Gamma Ray American Petroleum Institute Units)
Concentration of Oftedalite per GRapi unit = 1.78 (%)
Estimated Radioactivity from Oftedalite - barely detectable
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Oftedalite Classification
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Dana Class: |
63.02.01a.19 (63)Cyclosilicate Condensed Rings |
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(63.02)6-membered rings |
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(63.02.01a)Milarite - Osumilite group (Milarite - Osumilite subgroup) |
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63.02.01a.01 Brannockite KSn2Li3Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.02 Chayesite K(Mg,Fe)4Fe(Si12O30) P 6/mcc 6/m 2/m 2/m |
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63.02.01a.03 Darapiosite KNa2Zr[Li(Mn,Zr)2Si12O30] P 6/mcc 6/m 2/m 2/m |
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63.02.01a.04 Eifelite KNa3Mg4Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.05 Merrihueite (K,Na)2(Fe,Mg)5Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.06 Osumilite-(Fe) (K,Na)(Fe,Mg)2(Al,Fe)3(Si,Al)12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.07 Osumilite-(Mg) (K,Na)(Mg,Fe)2(Al,Fe)3(Si,Al)12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.08 Poudretteite KNa2B3Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.09 Sugilite KNa2(Fe,Mn,Al)2Li3Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.10 Yagiite (Na,K)3Mg4(Al,Mg)6(Si,Al)24O60 P 6/mmc 6/m 2/m 2/m |
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63.02.01a.11 Dusmatovite K(K,Na,[])(Mn,Y,Zr)2(Zn,Li)3Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.12 Milarite K2Ca4Al2Be4Si24O60•(H2O) P 6/mcc 6/m 2/m 2/m |
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63.02.01a.13 Sogdianite (K,Na)2(Li,Fe,Al)3ZrSi12O30 P 6/mmm 6/m 2/m 2/m |
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63.02.01a.14 Roedderite (Na,K)2(Mg,Fe)5Si12O30 P 63/mmc 6/m 2/m 2/m |
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63.02.01a.15 Berezanskite! KLi3Ti2Si12O30 P 6/mcc 6/m 2/m 2/m |
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63.02.01a.16 Shibkovite! K(Ca,Mn,Na)2(K2-x,[]x)2ZnSi12O30(x~0.8) P 6/mcc 6/m 2/m 2/m |
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63.02.01a.17 Trattnerite! (Fe,Mg)2(Mg,Fe)3(Si12O30) P 6/mcc 6/m 2/m 2/m |
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63.02.01a.18 Almarudite! K([],Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30] P 6/mcc 6/m 2/m 2/m |
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63.02.01a.19 Oftedalite! (Sc,Ca)2KBe3Si12O30 P 6/mmc 6/m 2/m 2/m |
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63.02.01a.20 Klochite ([]1Na1)KFe2Zn3[Si12O30] P 6/mcc 6/m 2/m 2/m |
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63.02.01a.21 Friedrichbeckeite! K([],Na)Mg2(Be2Mg)Si12O30 P 6/mcc 6/m 2/m 2/m |
Strunz Class: |
09.CM.05 09 - SILICATES (Germanates) |
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09.C - Cyclosilicates |
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09.CM -[Si6O18]12- 6-membered double rings (sechser-Doppelringe) |
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09.CM.05 Brannockite KSn2Li3Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Armenite BaCa2Al6Si9O30•2(H2O) Pnc2 mm2 |
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09.CM.05 Berezanskite! KLi3Ti2Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Dusmatovite K(K,Na,[])(Mn,Y,Zr)2(Zn,Li)3Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Chayesite K(Mg,Fe)4Fe(Si12O30) P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Shibkovite! K(Ca,Mn,Na)2(K2-x,[]x)2ZnSi12O30(x~0.8) P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Eifelite KNa3Mg4Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Darapiosite KNa2Zr[Li(Mn,Zr)2Si12O30] P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Merrihueite (K,Na)2(Fe,Mg)5Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Roedderite (Na,K)2(Mg,Fe)5Si12O30 P 63/mmc 6/m 2/m 2/m |
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09.CM.05 Milarite K2Ca4Al2Be4Si24O60•(H2O) P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Osumilite-(Fe) (K,Na)(Fe,Mg)2(Al,Fe)3(Si,Al)12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Osumilite-(Mg) (K,Na)(Mg,Fe)2(Al,Fe)3(Si,Al)12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Poudretteite KNa2B3Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Sugilite KNa2(Fe,Mn,Al)2Li3Si12O30 P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Sogdianite (K,Na)2(Li,Fe,Al)3ZrSi12O30 P 6/mmm 6/m 2/m 2/m |
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09.CM.05 Oftedalite! (Sc,Ca)2KBe3Si12O30 P 6/mmc 6/m 2/m 2/m |
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09.CM.05 Yagiite (Na,K)3Mg4(Al,Mg)6(Si,Al)24O60 P 6/mmc 6/m 2/m 2/m |
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09.CM.05 Trattnerite! (Fe,Mg)2(Mg,Fe)3(Si12O30) P 6/mcc 6/m 2/m 2/m |
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09.CM.05 Almarudite! K([],Na)2(Mn,Fe,Mg)2(Be,Al)3[Si12O30] P 6/mcc 6/m 2/m 2/m |
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Other Oftedalite Information
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References: |
NAME( AmMin, v91, p1948) PHYS. PROP.(AmMin, v91, p1948) OPTIC PROP.(AmMin, v91, p1948) |
See Also: |
Links to other databases for Oftedalite :
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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Print or Cut-and-Paste your Oftedalite Specimen Label here :
Oftedalite
(Sc,Ca)2KBe3Si12O30
Dana No: 63.02.01a.19 Strunz No: 09.CM.05
Locality:
Notes:
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