Oftedalite (original) (raw)

A valid IMA mineral species

About OftedaliteHide

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Formula:

K◻2(ScCa)Be3[Si12O30]

Previously given as K(Sc,Ca,Mn2+)2◻2[(Be,Al)3Si12O30].

The current IMA formula (as of Sept. 2023) shows the A site is 2Sc, but this combination doesn't allow the overall formula to charge balance, and appears to be a typo.

In Gagné & Hawthorne (2016), the A site is instead shown as (ScCa), and this combination does charge balance the overall formula.

Specific Gravity:

2.614 (Calculated)

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."

Unique combination of elements (status: 04.2024).

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:27498:4

a2fa7e23-2eed-4abf-9add-1a68a2afc38b

IMA Classification of OftedaliteHide

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IMA Formula:

K(ScCa)◻2Be3Si12O30

Classification of OftedaliteHide

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9.CM.05

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

Mineral SymbolsHide

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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.

Physical Properties of OftedaliteHide

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Cleavage:

Poor/Indistinct
Parallel to {001}

Density:

2.614 g/cm3 (Calculated)

Optical Data of OftedaliteHide

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RI values:

_n_ω = 1.554 - 1.558 _n_ε = 1.551 - 1.555

δ = 0.003

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Pleochroism:

Non-pleochroic

Chemistry of OftedaliteHide

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Mindat Formula:

K◻2(ScCa)Be3[Si12O30]

Previously given as K(Sc,Ca,Mn2+)2◻2[(Be,Al)3Si12O30].

The current IMA formula (as of Sept. 2023) shows the A site is 2Sc, but this combination doesn't allow the overall formula to charge balance, and appears to be a typo.

In Gagné & Hawthorne (2016), the A site is instead shown as (ScCa), and this combination does charge balance the overall formula.

Crystallography of OftedaliteHide

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Class (H-M):

6/m m m _(_6/_m_2/_m_2/m ) - Dihexagonal Dipyramidal

Cell Parameters:

a = 10.097 Å, c = 13.991 Å

Morphology:

Hexagonal prisms, with prominent {100} and {001} forms.

Crystal StructureHide

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ID	Species	Reference	Link	Year	Locality	Pressure (GPa)	Temp (K)
0006096	Oftedalite	Cooper M A, Hawthorne F C, Ball N A, Cerny P, Kristiansen R (2006) Oftedalite, (Sc,Ca,Mn2+)2 K (Be,Al)3 Si12 O30, a new member of the milarite group from the Heftetjern pegmatite, Tordal, Norway: description and crystal structure The Canadian Mineralogist 44 943-949		2006	Heftetjern pegmatite, Tordal, Norway	0	293

CIF Raw Data - click here to close

Epitaxial Relationships of OftedaliteHide

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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

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Powder Diffraction Data:

Comments:

Recorded on type material; Format of data: d/Å (I/%) (hkl)

Geological EnvironmentHide

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Type Occurrence of OftedaliteHide

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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.

Place of Conservation of Type Material:

The Canadian Museum of Nature, Ottawa, Ontario, Canada (H04/98).
Steiermärkisches Landesmuseum, Graz, Austria.

Geological Setting of Type Material:

Associated Minerals at Type Locality:

Synonyms of OftedaliteHide

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Other Language Names for OftedaliteHide

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Simplified Chinese:钪整柱石

Traditional Chinese:鈧整柱石

Relationship of Oftedalite to other SpeciesHide

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Other Members of this group:

Related Minerals - Strunz-mindat GroupingHide

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Fluorescence of OftedaliteHide

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Other InformationHide

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Health Risks:

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

Internet Links for OftedaliteHide

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References for OftedaliteHide

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Reference List:

Cooper, M. A., Hawthorne, F. C., Ball, N. A., Černý, Petr, Kristiansen, Roy (2006) Oftedalite, (ScCa)KBe3Si12O30, a new mineral species of the milarite group from the Heftetjern pegmatite, Tørdal, Norway: description and crystal structure. The Canadian Mineralogist, 44 (4) 943-949 doi:10.2113/gscanmin.44.4.943

Localities for OftedaliteHide

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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

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- 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). 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.