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Oftedalite

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Formula:
K(Sc,Ca,Mn2+)22[(Be,Al)3Si12O30]
Colour:
Greyish white
Lustre:
Vitreous
Hardness:
6
Specific Gravity:
2.614 (Calculated)
Crystal System:
Hexagonal
Member of:
Name:
Named by M.A. Cooper, F.C. Hawthorne, N.A. Ball, P. Černý, R. Kristiansen in 2006 in honor of Ivar Werner Oftedal (1894–1976), Professor of Mineralogy at the Institute of Geology, University of Oslo (1949, Larvik, Norway - 1964), "who contributed extensively to the geochemistry of scandium, and who wrote the first papers on the mineralogy of the Tørdal pegmatites."
This page provides mineralogical data about Oftedalite.


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Classification of OftedaliteHide

Approved
Approval Year:
2004
First Published:
2006
9.CM.05

9 : SILICATES (Germanates)
C : Cyclosilicates
M : [Si6O18]12- 6-membered double rings (sechser-Doppelringe)

Physical Properties of OftedaliteHide

Vitreous
Colour:
Greyish white
Streak:
White
Hardness:
Tenacity:
Brittle
Cleavage:
Poor/Indistinct
parallel to {001}
Fracture:
Conchoidal
Density:
2.614 g/cm3 (Calculated)

Optical Data of OftedaliteHide

Type:
Uniaxial (-)
RI values:
nω = 1.554 - 1.558 nε = 1.551 - 1.555
Max Birefringence:
δ = 0.003
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low
Pleochroism:
Non-pleochroic

Chemical Properties of OftedaliteHide

Formula:
K(Sc,Ca,Mn2+)22[(Be,Al)3Si12O30]
IMA Formula:
KSc2(Be3AlSi11)O30

Crystallography of OftedaliteHide

Crystal System:
Hexagonal
Class (H-M):
6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:
P6/mcc
Cell Parameters:
a = 10.097 Å, c = 13.991 Å
Ratio:
a:c = 1 : 1.386
Unit Cell V:
1235.3 ų
Z:
2

Epitaxial Relationships of OftedaliteHide

Epitaxial Minerals:
MilariteK2Ca4Al2Be4Si24O60 · H2O
Epitaxy Comments:
frequently with very thin crystals of Sc-free milarite up to ~10–20 µm across in parallel orientation on the (001) faces

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.229 (10)
4.097 (7)
5.044 (5)
3.504 (5)
7.012 (4)
1.836 (4)
1.751 (4)
2.735 (3)
Comments:
Recorded on type material; Format of data: d/Å (I/%) (hkl)

Type Occurrence of OftedaliteHide

General Appearance of Type Material:
short prismatic crystals up to 100 µm in diameter, or as a product of replacement together with other Sc-bearing minerals
Geological Setting of Type Material:
Granitic pegmatite

Synonyms of OftedaliteHide

Other Language Names for OftedaliteHide

German:Oftedalit
Simplified Chinese:钪整柱石
Traditional Chinese:鈧整柱石

Relationship of Oftedalite to other SpeciesHide

Member of:
Other Members of this group:
Agakhanovite-(Y)(YCa)□2KBe3Si12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
AlmaruditeK(□,Na)2(Mn2+,Fe2+,Mg)2(Be,Al)3[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm
ArmeniteBaCa2Al6Si9O30 · 2H2OOrth. mmm (2/m 2/m 2/m) : Pnna
BerezanskiteK□2Li3(Ti,Zr,Sn)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
Brannockite(K,Na)□2Li3(Sn,Zr,Ti)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
DarapiositeK(Na,◻,K)2(Li,Zn,Fe)3(Mn,Zr,Y)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
DusmatoviteK(Na,□)2(Zn,Li)3(Mn2+,Y,Zr)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
EifeliteKNa3Mg4Si12O30Hex.
FriedrichbeckeiteK(□0.5Na0.5)2Mg2Be3Si12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
Klöchite(□Na)KFe2+2Zn3(Si12O30)Hex. 6/mmm (6/m 2/m 2/m) : P63/mmc
Merrihueite(K,Na)2(Fe,Mg)5Si12O30Hex.
MilariteK2Ca4Al2Be4Si24O60 · H2OHex. 6/mmm (6/m 2/m 2/m) : P6/mcc
Osumilite(K,Na)(Fe2+,Mg)2(Al,Fe3+)3(Si,Al)12O30Hex.
Osumilite-(Mg)KMg2Al3(Al2Si10)O30 Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
PoudretteiteKNa2B3Si12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
Roedderite(Na,K)2(Mg,Fe)5Si12O30Hex. 6 m2 : P62c
ShibkoviteK(□,K,Na)2Zn3Ca2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
SogdianiteK(□,Na)2Li3(Zr,Fe,Ti)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
SugiliteK(Na,□)2Li3(Fe,Mn,Al,Zr)2[Si12O30]Hex.
Trattnerite□(Fe3+,Mg,Fe2+)2(Mg,Fe2+,Fe3+)3(Si12O30)Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
Yagiite(Na,K)3Mg4(Al,Mg)6(Si,Al)24O60Hex. 6/mmm (6/m 2/m 2/m)

Related Minerals - Nickel-Strunz GroupingHide

9.CM.05ArmeniteBaCa2Al6Si9O30 · 2H2OOrth. mmm (2/m 2/m 2/m) : Pnna
9.CM.05Brannockite(K,Na)□2Li3(Sn,Zr,Ti)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05ChayesiteK(Mg,Fe)4FeSi12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05DarapiositeK(Na,◻,K)2(Li,Zn,Fe)3(Mn,Zr,Y)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05EifeliteKNa3Mg4Si12O30Hex.
9.CM.05Merrihueite(K,Na)2(Fe,Mg)5Si12O30Hex.
9.CM.05MilariteK2Ca4Al2Be4Si24O60 · H2OHex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05Osumilite-(Mg)KMg2Al3(Al2Si10)O30 Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05Osumilite(K,Na)(Fe2+,Mg)2(Al,Fe3+)3(Si,Al)12O30Hex.
9.CM.05PoudretteiteKNa2B3Si12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05Roedderite(Na,K)2(Mg,Fe)5Si12O30Hex. 6 m2 : P62c
9.CM.05SogdianiteK(□,Na)2Li3(Zr,Fe,Ti)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05SugiliteK(Na,□)2Li3(Fe,Mn,Al,Zr)2[Si12O30]Hex.
9.CM.05Yagiite(Na,K)3Mg4(Al,Mg)6(Si,Al)24O60Hex. 6/mmm (6/m 2/m 2/m)
9.CM.05BerezanskiteK□2Li3(Ti,Zr,Sn)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05DusmatoviteK(Na,□)2(Zn,Li)3(Mn2+,Y,Zr)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05ShibkoviteK(□,K,Na)2Zn3Ca2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.05AlmaruditeK(□,Na)2(Mn2+,Fe2+,Mg)2(Be,Al)3[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mmm
9.CM.05Trattnerite□(Fe3+,Mg,Fe2+)2(Mg,Fe2+,Fe3+)3(Si12O30)Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
9.CM.10FaizieviteK2Na(Ca6Na)Ti4Li6[F2|Si24O66]Tric. 1 : P1

Fluorescence of OftedaliteHide

None observed

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for OftedaliteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
ristiansen, R. (2005) Milarittgruppens mineraler i Norge (The milarite group minerals in Norway). Norsk Bergverksmuseums Skrift: 30: 21-29.
Cooper, M.A., Hawthorne, F.C., Ball, N.A., Černý, P., Kristiansen, R. (2006) Oftedalite, (Sc,Ca,Mn2+)2K(Be,Al)3Si12O30, a new member of the milarite group from the Heftetjern pegmatite, Tørdal, Norway: description and crystal structure. Canadian Mineralogist: 44: 943-949.
Locock, A.J., Ercit, T.S., Kjellman, J., Piilonen, C. (2006) New mineral names. American Mineralogist: 91: 1945-1954.

Internet Links for OftedaliteHide

Localities for OftedaliteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Norway (TL)
 
  • Telemark
    • Drangedal
      • Tørdal
Cooper, M.A., Hawthorne, F.C., Ball, N.A., Černý, P., Kristiansen, R. (2006): Oftedalite, (ScCa)KBe3Si12O30, a new mineral species of the milarite group from the Heftetjern pegmatite, Tørdal, Norway: description and crystal structure. Canadian Mineralogist, 44, 943-949; Kristiansen, R. (2005): Milarittgruppens mineraler i Norge. Norsk Bergverksmuseum Skrifter, 30, 21-29
Mineral and/or Locality  
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