Classification of Acuminite |
| IMA status: | Approved 1986 |
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| Strunz 8th edition ID: | 3/C.01-20
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| Strunz 9th edition ID: | 3.CC.10
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| Nickel-Strunz 10th (pending) edition ID: | 3.CC.10
3 : HALIDES C : Complex halides C : Soro-aluminofluorides |
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| Dana 8th edition ID: | 11.6.17.1
11 : HALIDE COMPLEXES 6 : Aluminofluorides - Isolated Octahedra |
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| Hey's CIM Ref.: | 8.4.15
8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates 4 : Halides of the alkaline earths and Mg |
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| mindat.org URL: | http://www.mindat.org/min-19.html Please feel free to link to this page. |
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Type Occurrence of Acuminite |
| Type Locality: | Cryolite deposit, Ivittuut (Ivigtut), Arsuk Firth, Arsuk, Kitaa (West Greenland) Province, Greenland |
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| General Appearance of Type Material: | acute dipyramidal crystals, resembling spear points, to 1 mm |
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| Place of Conservation of Type Material: | University of Copenhagen, Copenhagen, Denmark |
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| Geological Setting of type material: | Strontium-rich portion of a cryolite deposit |
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| Associated Minerals at type locality: | |
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Physical Properties of Acuminite |
| Lustre: | Vitreous |
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| Diaphaneity (Transparency): | Transparent |
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| Colour: | Colourless, white, becomes yellow on exposure to x-rays |
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| Streak: | white |
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| Hardness (Mohs): | 3½ |
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| Cleavage: | Perfect on {001} |
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| Density (measured): | 3.295 g/cm3 |
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| Density (calculated): | 3.305 g/cm3 |
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Crystallography of Acuminite |
| Crystal System: | Monoclinic |
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| Cell Parameters: | a = 13.223Å, b = 5.175Å, c = 14.251Å β = 11.61° |
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| Ratio: | a:b:c = 2.555 : 1 : 2.754 |
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| Unit Cell Volume: | V 196.25 ų (Calculated from Unit Cell) |
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| Z: | 8 |
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| Morphology: | {110}, {_111}, rarely {_112} |
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| Twinning: | on {100}, as contact twins |
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| X-Ray Powder Diffraction: | | d-spacing | | Intensity | | 2.075 | | (9) | | 3.286 | | (8) | | 3.310 | | (8) | | 3.353 | | (10) | | 3.505 | | (10) | | 4.706 | | (10) |
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| Comments: | Recorded on type material |
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Optical Data of Acuminite |
| Type: | Biaxial (+) |
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| RI values: | nα = 1.451 nβ = 1.453 nγ = 1.462 - 1.463 |
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| 2V: | Measured: 46° to 57°, Calculated: 50° to 52° |
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| Maximum Birefringence: | δ = 0.012
 Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration. |
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| Surface Relief: | Moderate |
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| Dispersion: | r > v, strong |
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Chemical Properties of Acuminite |
| Formula: | |
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| Essential elements: | Al, F, H, O, Sr |
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| All elements listed in formula: | Al, F, H, O, Sr |
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| Analyical Data: | Ca and Sr determined by atomic absorption spectroscopy (AA), Al by CDTA, F electrochemically; OH calculated from the charge balance, H2O from theory
Ca (0.02)
Sr (37.04)
Al (11.86)
F (33.52)
OH (6.82)
H2O (7.80)
sum 97.06 wt.-% |
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| Empirical Formula: | |
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| Common Impurities: | Ca |
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Relationship of Acuminite to other Species |
| Related Minerals - Nickel-Strunz Grouping): | |
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| Related Minerals - Hey's Index Grouping: | |
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Other Names for Acuminite |
| Synonyms: | |
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| German names: | |
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| Russian names: | |
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| Spanish names: | |
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Other Information |
| Health Warning: | No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care. |
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References for Acuminite |
| Reference List: | Pauly, H. and Petersen, O. V. (1987): Acuminite, a new Sr fluoride from Ivigtut, South Greenland. Neues Jahrbuch für Mineralogie, Monatshefte, 502-514. - American Mineralogist (1988), 73, 1492 (abstract).
Krogh Andersen, E., Ploug-Sorensen, G. and Leonardsen, E. (1991): The structure of acuminite, a strontium aluminium fluoride mineral. Zeitschrift für Kristallographie 194, 221-227.
Anthony, J. W. et al. (1997): Handbook of Mineralogy, Vol. 3, 2. |
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Internet Links for Acuminite |
| Search Engines: |
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| External Links: | Look for Acuminite on WebmineralLook for Acuminite on Athena MineralogyLook for Acuminite on WikipediaLook for Acuminite on Mineralien AtlasRaman and XRD data at RRUFF projectAmerican Mineralogist Crystal Structure DatabaseSearch for Acuminite in the Natural History Museum (London) online catalogueAcuminite details from Handbook of Mineralogy (PDF) |
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| Mineral Dealers: | Search for Acuminite at Thames Valley MineralsRare and Unusual minerals at Mineralogical Research CompanyBuy Minerals and Crystals from Crystalarium.comLapis Mineral MagazinBuy from David K Joyce mineralsWright's Rock Shop - excellent mineral specimens since 1970Mineral Classics - Worldwide Collector Quality Minerals and GemsWendel Minerals - Auktion & ShopThe Arkenstone - Fine MineralsTop quality minerals from Kristalle of CaliforniaFind Acuminite on www.crystalclassics.co.ukSearch for Acuminite on minvision.com |
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| Jobs: | Mining & Geology Jobs |
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Localities for Acuminite |
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