IMA 2018-050 = potassic-jeanlouisite

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Marco E. Ciriotti
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Iscritto il: ven 25 giu, 2004 11:31
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IMA 2018-050 = potassic-jeanlouisite

Messaggio da Marco E. Ciriotti » sab 29 giu, 2019 11:53

Prossima pubblicazione.

Referenza:
▪ Oberti, R., Boiocchi, M., Hawthorne, F.C., Della Ventura, G., Farber, G. (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, (in press).

Abstract:
jeanlouisite, ideally K(NaCa)(Mg4Ti)Si8O22O2, is the first characterized species of oxo amphibole related to the sodium-calcium group, and derives from potassic richterite via the coupled exchange CMg-1 WOH--2 CTi4+1 WO2-2. The mineral and the mineral name were approved by the IMA-CNMNC, vote 2018-050. 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)Σ1.00 B(Ca0.93Na1.02Mg0.04Mn2+0.01)Σ2.00 C(Mg3.85 Fe2+0.16 Ni0.01Fe3+0.33V3+0.01 Ti0.65)Σ5.01T(Si7.76Al0.09 Ti0.15)Σ8.00 O22 W[O1.53F0.47]Σ2.00. The holotype crystal is biaxial (-), with α = 1.674(2), β = 1.688(2), γ = 1.698(2) and 2V (meas.) = 79(1)º, 2V (calc.) = 79.8º. 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, space group C2/m. The strongest ten reflections in the X-ray powder pattern [d values (in Å), I, (hkl)] are: 2.703, 100, (151); 3.380, 87, (131); 2.541, 80, (-202); 3.151, 70, (310); 3.284, 68, (240); 8.472, 59, (110); 2.587, 52, (061); 2.945, 50, (221,-151); 2.162, 47, (261); 2.750, 45, (-331).
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 25910
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Re: IMA 2018-050 = potassic-jeanlouisite

Messaggio da Marco E. Ciriotti » lun 02 set, 2019 15:12

Pubblicazione effettuata.

Referenza:
▪ Oberti, R., Boiocchi, M., Hawthorne, F.C., Della Ventura, G., Farber, G. (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, 587-593.

Abstract:
jeanlouisite, ideally K(NaCa)(Mg4Ti)Si8O22O2, is the first characterized species of oxo amphibole related to the sodium-calcium group, and derives from potassic richterite via the coupled exchange CMg-1 WOH--2 CTi4+1 WO2-2. The mineral and the mineral name were approved by the IMA-CNMNC, vote 2018-050. 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)Σ1.00 B(Ca0.93Na1.02Mg0.04Mn2+0.01)Σ2.00 C(Mg3.85 Fe2+0.16 Ni0.01Fe3+0.33V3+0.01 Ti0.65)Σ5.01T(Si7.76Al0.09 Ti0.15)Σ8.00 O22 W[O1.53F0.47]Σ2.00. The holotype crystal is biaxial (-), with α = 1.674(2), β = 1.688(2), γ = 1.698(2) and 2V (meas.) = 79(1)º, 2V (calc.) = 79.8º. 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, space group C2/m. The strongest ten reflections in the X-ray powder pattern [d values (in Å), I, (hkl)] are: 2.703, 100, (151); 3.380, 87, (131); 2.541, 80, (-202); 3.151, 70, (310); 3.284, 68, (240); 8.472, 59, (110); 2.587, 52, (061); 2.945, 50, (221,-151); 2.162, 47, (261); 2.750, 45, (-331).
Marco E. Ciriotti

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