Reference Type | Journal (article/letter/editorial) |
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Title | Potassic-jeanlouisite from Leucite Hill, Wyoming, USA, ideally K(NaCa)(Mg4Ti)Si8O22O2: the first species of oxo amphibole in the sodium–calcium subgroup |
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Journal | Mineralogical Magazine |
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Authors | Oberti, Roberta | Author |
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Boiocchi, Massimo | Author |
Hawthorne, Frank C. | Author |
Della Ventura, Giancarlo | Author |
Färber, Gunnar | Author |
Year | 2019 (August) | Volume | 83 |
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Page(s) | 587-593 | Issue | 4 |
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Publisher | Mineralogical Society |
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DOI | doi:10.1180/mgm.2019.38Search in ResearchGate |
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Mindat Ref. ID | 245170 | Long-form Identifier | mindat:1:5:245170:5 |
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GUID | a62d2ee0-661a-4e15-bc69-55bd55a98a04 |
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Full Reference | Oberti, Roberta, Boiocchi, Massimo, Hawthorne, Frank C., Della Ventura, Giancarlo, Färber, Gunnar (2019) Potassic-jeanlouisite from Leucite Hill, Wyoming, USA, ideally K(NaCa)(Mg4Ti)Si8O22O2: the first species of oxo amphibole in the sodium–calcium subgroup. Mineralogical Magazine, 83 (4) 587-593 doi:10.1180/mgm.2019.38 |
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Plain Text | Oberti, Roberta, Boiocchi, Massimo, Hawthorne, Frank C., Della Ventura, Giancarlo, Färber, Gunnar (2019) Potassic-jeanlouisite from Leucite Hill, Wyoming, USA, ideally K(NaCa)(Mg4Ti)Si8O22O2: the first species of oxo amphibole in the sodium–calcium subgroup. Mineralogical Magazine, 83 (4) 587-593 doi:10.1180/mgm.2019.38 |
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Abstract/Notes | AbstractPotassic-jeanlouisite, ideally K(NaCa)(Mg4Ti)Si8O22O2, is the first characterised species of oxo amphibole related to the sodium–calcium group, and derives from potassic richterite via the coupled exchange CMg–1W${\rm OH}_{{\rm \ndash 2}}^{\ndash}{} ^{\rm C}{\rm Ti}_1^{{\rm 4 +}} {} ^{\rm W}\!{\rm O}_2^{2\ndash} $. The mineral and the mineral name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification, IMA2018-050. Potassic-jeanlouisite was found in a specimen of leucite which is found in the lava layers, collected in the active gravel quarry on Zirkle Mesa, Leucite Hills, Wyoming, USA. It occurs as pale yellow to colourless acicular crystals in small vugs. The empirical formula derived from electron microprobe analysis and single-crystal structure refinement is: A(K0.84Na0.16)Σ1.00B(Ca0.93Na1.02Mg0.04${\rm Mn}_{{\rm 0}{\rm. 01}}^{2 +} $)Σ2.00C(Mg3.85${\rm Fe}_{{\rm 0}{\rm. 16}}^{2 +} $Ni0.01${\rm Fe}_{{\rm 0}{\rm. 33}}^{3 +} {\rm V}_{{\rm 0}{\rm. 01}}^{3 +} $Ti0.65)Σ5.01T(Si7.76Al0.09Ti0.15)Σ8.00O22W[O1.53F0.47]Σ2.00. The holotype crystal is biaxial (–), with α = 1.674(2), β = 1.688(2), γ = 1.698(2), 2Vmeas. = 79(1)° and 2Vcalc. = 79.8°. The unit-cell parameters are a = 9.9372(10), b = 18.010(2), c = 5.2808(5) Å, β = 104.955(2)°, V = 913.1(2) Å3, Z = 2 and space group C2/m. The strongest eight reflections in the powder X-ray pattern [d values (in Å) (I) (hkl)] are: 2.703 (100) (151); 3.380 (87) (131); 2.541 (80) ($\bar 2$02); 3.151 (70) (310); 3.284 (68) (240); 8.472 (59) (110); 2.587 (52) (061); 2.945 (50) (221,$\bar 1$51). |
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