IMA 2017-010 = levantite

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Marco E. Ciriotti
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IMA 2017-010 = levantite

Messaggio da Marco E. Ciriotti » sab 15 giu, 2019 10:37

Prossima pubblicazione.

Referenza:
▪ Galuskin, E.V., Krüger, B., Galuskina, I.O., Krüger, H., Vapnik, Y., Pauluhn, A., Olieric, V. (2019): Levantite, KCa3(Al2Si3)O11(PO4), a new latiumite group mineral from pyrometamorphic rock of the Hatrurim Basin, Negev Desert, Israel. Mineralogical Magazine, 83, (in press).

Abstract:
Levantite, with end-member formula KCa3(Al2Si3)O11(PO4) is a phosphorus analogue of latiumite, KCa3(Al3Si2)O11(SO4, CO3) found in gehlenite-wollastonite hornfels in the area of the Parsa Mt, Negev Desert, Israel. Levantite forms later zones on long-prismatic crystals of latiumite. Rarer homogeneous colourless levantite crystals up to 0.2 mm in length and with mean composition (K0.94Ba0.01Na0.01□0.04)Σ1.00(Ca2.96Mg0.03)Σ2.99{(Si2.69Al2.06Fe3+0.16P0.06)Σ4.97O11} [(PO4)0.65(SO4)0.35]Σ1.00 were noted. Minerals of the levantite-latiumite series are associated with gehlenite, wollastonite, clinopyroxene of the esseneite-diopside series, anorthite and Ti-bearing andradite. Levantite crystalises in space group P21 with unit cell parameters a = 12.1006(9) Å, b = 5.1103(4) Å, c = 10.8252(9) Å, β = 107.237(8)°, V = 639.34(9) Å3, Z = 2. The structure of levantite is analogous to latiumite. It is formed by tetrahedral hybrid zweier double layers [(Si,Al)10O22] connected by Ca atoms. Three Ca atoms linked to different double layers are bridged over by (PO4)- and minor (SO4)- groups. In cavities between two supperimposed zweier double layers reside K-atoms. Measured micro-indentation hardness of levantite VHN50 = 580(19) (mean of 14) and range - 550-611 kg/mm2 - matching to 5 in the Mohs scale. Cleavage is good on (100). Twinning on (100) is polysynthetic or simple. Calculated density is 2.957 g·cm-3. Levantite is an optically negative mineral, α = 1.608(2), β = 1.618(2) and γ = 1.622(2) (delta = 589 nm), 2Vx (meas.): 70(±5)°, 2Vx (calc.): 64.3°. Dispersion: r > v, weak, orientation: Z = b; X ^ c = 22-27°, non-pleochroic. Minerals of the levantite-latiumite series from Israel show characteristic Raman spectra with the main bands at 994 cm-1 [ν1(SO4)2-] and 945 cm-1 [ν1(PO4)3-]. Band intensity ν1(PO4)3-/ν1(SO4) ratio is well correlated with P and S contents in the investigated minerals. The following strong lines are represented in powder diffraction pattern (d/I): 3.0762(100), 2.8551(96), 2.9704(92), 2.8573(83), 2.5552(66), 2.8228(48), 2.8893(40), 3.0634(30).
Marco E. Ciriotti

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Marco E. Ciriotti
Messaggi: 25650
Iscritto il: ven 25 giu, 2004 11:31
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Re: IMA 2017-010 = levantite

Messaggio da Marco E. Ciriotti » sab 15 giu, 2019 10:39

latiumite group

Latiumite KCa3[Si3Al2O11](SO4)
Levantite KCa3[Si3Al2O11](PO4)
Queitite PbPb3[Si3Zn2O11](SO4)
Tuscanite [K0.5(H2O)0.5]Ca3[Si3Al2O11](SO4)(ОН)0.5
Marco E. Ciriotti

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