IMA 2017-079 = janchevite

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Marco E. Ciriotti
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IMA 2017-079 = janchevite

Messaggio da Marco E. Ciriotti » sab 14 apr, 2018 11:20

Prossima pubblicazione.

Referenza:
▪ Chukanov, N.V., Nekrasova, D.O., Siidra, O.I., Polekhovsky, Yu.S., Pekov, I.V. (2018): Janchevite, Pb7V5+(O8.5□0.5)Cl2, a new mineral from Kombat mine, Namibia. Canadian Mineralogist, 56, (in press).

Abstract:
The new mineral janchevite was discovered in Mn-oxide ore from the Kombat mine, Grootfontein district, Otjozondjupa region, Namibia. Associated minerals are baryte, hausmannite, calcite, magnesite, and kombatite. Janchevite forms orange-red thick tabular anhedral to subhedral grains up to 0.4 × 0.8 × 0.8 mm in size. The luster is adamantine. The mineral is brittle, with Mohs' hardness of 2½. Distinct cleavage on {001} is observed. Dcalc = 8.16 g/cm3. The reflectance values [Rmax/Rmin, % (λ, nm)] are: 20.56/20.06 (470), 19.20/18.81 (546), 19.06/18.59 (589), 19.31/18.85 (650). An infrared spectrum indicates the absence of H-bearing groups and indicates V and Mo valences of 5+ and 6+, respectively. The chemical composition is (electron microprobe, wt.%): PbO 91.64, SiO2 0.45, V2O5 1.95, MoO3 2.41, Cl 4.16, –O=Cl –0.94, total 99.67. The empirical formula based on (Pb + V + Mo + Si) = 8 apfu is Pb7.20V5+0.38Mo6+0.29Si0.13Cl2.06O8.25. Janchevite is the V-dominant analogue of parkinsonite. The mineral is tetragonal and its unit-cell parameters as determined from single-crystal X-ray diffraction data are: a 3.9591(5), c 22.6897(3) Å, V 355.65(1) Å3; Z = 1. Powder X-ray diffraction data conform to the space group I4/mmm; the strongest lines of the PXRD pattern [d, Å (I/I0, %) (hkl)] are: 3.889 (24) (011), 3.501 (31) (013), 2.979 (86) (015), 2.833 (25) (008), 2.794 (100) (110), 1.992 (26) (118), 1.988 (49) (020), 1.649 (46) (215). Janchevite is named in honor of the prominent Macedonian mineralogist Prof. Dr. Simeon Janchev (b. 1942).
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: 24390
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 2017-079 = janchevite

Messaggio da Marco E. Ciriotti » lun 21 mag, 2018 22:32

Pubblicazione effettuata.

Referenza:
▪ Chukanov, N.V., Nekrasova, D.O., Siidra, O.I., Polekhovsky, Yu.S., Pekov, I.V. (2018): Janchevite, Pb7V5+(O8.5□0.5)Cl2, a new mineral from Kombat mine, Namibia. Canadian Mineralogist, 56, 159-165.
Marco E. Ciriotti

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

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