Classification of Oftedalite |
| IMA status: | Approved 2004 |
|---|
| Strunz 8th edition ID: | 8/E.22-
|
|---|
| Nickel-Strunz 10th (pending) edition ID: | 9.CM.05
9 : SILICATES (Germanates) C : Cyclosilicates M : [Si6O18]12- 6-membered double rings (sechser-Doppelringe) |
|---|
| mindat.org URL: | http://www.mindat.org/min-27498.html Please feel free to link to this page. |
|---|
Type Occurrence of Oftedalite |
| Type Locality: | Heftetjern pegmatite, Tørdal, Drangedal, Telemark, Norway |
|---|
| 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 |
|---|
Physical Properties of Oftedalite |
| Lustre: | Vitreous |
|---|
| Colour: | Greyish white |
|---|
| Streak: | White |
|---|
| Hardness (Mohs): | 6 |
|---|
| Tenacity: | Brittle |
|---|
| Cleavage: | Poor/Indistinct parallel to {001} |
|---|
| Fracture: | Conchoidal |
|---|
| Density (calculated): | 2.614 g/cm3 |
|---|
Crystallography of Oftedalite |
| Crystal System: | Hexagonal |
|---|
| Class (H-M): | 6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal |
|---|
| Space Group: | P6/mcc {P6/m 2/c 2/c} |
|---|
| Cell Parameters: | a = 10.097Å, c = 13.991Å
|
|---|
| Ratio: | a:c = 1 : 1.386 |
|---|
| Unit Cell Volume: | V 1235.3 ų |
|---|
| Z: | 2 |
|---|
Epitaxial Relationships of Oftedalite |
| Epitaxial Minerals: | |
|---|
| Epitaxi 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 Diffraction: | | d-spacing | | Intensity | | 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) |
|---|
Optical Data of Oftedalite |
| Type: | Uniaxial (-) |
|---|
| RI values: | nω = 1.554 - 1.558 nε = 1.551 - 1.555 |
|---|
| Maximum Birefringence: | δ = 0.003
 Chart 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 Oftedalite |
| Formula: | |
|---|
| All elements listed in formula: | Al, Be, Ca, K, Mn, O, Sc, Si |
|---|
| Analytical Data: | Results from electron microprobe analysis, Be content calculated per formula unit as n(Be) = 3 – n(Al);
Empirical formula based on 30 oxygen atoms per formula unit
SiO2 (73.32)
Al2O3 (0.47)
Sc2O3 (6.77)
Y2O3 (0.36)
FeO (0.26)
MnO (1.32)
CaO (4.49)
K2O (4.71)
BeO (7.41)
sum 99.11 wt.-% |
|---|
| Empirical Formula: | |
|---|
Relationship of Oftedalite to other Species |
Related Minerals - Nickel-Strunz Grouping):
- + | |
|---|
Other Names for Oftedalite |
| Synonyms: | |
|---|
| Other Languages: | |
|---|
Other Information |
| Fluorescence in UV light: | None observed |
|---|
| Health Warning: | No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care. |
|---|
References for Oftedalite |
Reference List:
- + | Kristiansen, 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. |
|---|
Internet Links for Oftedalite |
| Search Engines: |
Look for Oftedalite on Google
Look for Oftedalite images on Google |
|---|
| External Links: | Look for Oftedalite on WebmineralLook for Oftedalite on Athena MineralogyLook for Oftedalite on Mineralien AtlasRaman and XRD data at RRUFF projectAmerican Mineralogist Crystal Structure Database |
|---|
| Mineral Dealers: | Search for minerals at HeliodorPricedownminerals.com - Reverse Auctions and ShopWilensky Fine MineralsEdwards Minerals - Fine SpecimensBy minerals from YourMineralCollectionFind Oftedalite on www.crystalclassics.co.ukFabre Minerals - search for Oftedalite specimensBuy from David K Joyce mineralswebmineralsDAKOTA MATRIX offers Cabinet and Rare Species from Worldwide Localities.Buy fine minerals and gemstones from Pala InternationalSearch for - Oftedalite - on e-Rocks Mineral Sales & Auctions |
|---|
| Jobs: | Mining & Geology Jobs |
|---|
Localities for Oftedalite |
|