Vanadium-rich Muscovite from Austria: Crystal Structure, Chemical Analysis, and Spectroscopic Investigations

Abstract

The crystal structure of a green, transparent, vanadium-rich muscovite-2M 1 (V 2 O 3 ¼ 11.35 wt.%, one of the highest amounts reported to date in muscovite) with the optimized formula (K 0.94 Na 0.06 ) M2 (Al 1.20 V 3þ 0.61 Mg 0.12 Cr 3þ 0.07 ) T1 (Si 1.54 Al 0.46 ) T2 (Si 1.54 Al 0.46 )O 10 (OH) 2 and space group C2/c, a 5.2255(6), b 9.0704(10), c 20.0321(21)Å, b 95.773(2)8, Z ¼ 4 has been refined to R ¼ 6.97% for 1070 unique reflections (MoKa). This muscovite, which occurs in small quartz veins in graphite schist from Weinberg mountain, near the village of Amstall, Lower Austria, is distinctly low in Cr (Cr 2 O 3~1 .4 wt.%) and Mg (MgO~1.1 wt.%); Fe, Mn, and Ti are below detection limit. All octahedral cations occupy the M2 site, and the average octahedral bond (M2-O) distance is 1.953Å. Structural distortions include a ¼ 8.898 and Dz ¼ 0.193Å, resulting in an interlayer spacing of 3.35 A. The optical absorption spectrum of this V-rich muscovite shows absorption features at 427 and 609 nm that define a transmission window centered at 523 nm. These absorption features are consistent with those expected for V 3þ in mica, but the 609 nm band has a slightly longer wavelength than in low-V micas.

Polygenic chamosite from a hydrothermalized oolitic ironstone (Saint-Aubin-des-Châteaux, Armorican Massif, France): crystal chemistry, visible–near-infrared spectroscopy (red variety) and geochemical significance

“…The weak band at ~620 nm (Fig. 5) may correspond to the large absorption band at 609 nm observed in a green V-rich, Fe-free muscovite, which corresponds to a V 3+ electronic transition (Ertl et al , 2019).…”

“…When substituting as traces or minor components in oxides, V 4+ gives a green colour, as in malayaite (CaSnSiO 5 ), where V 4+ replaces Sn 4+ (Joo & Lee, 2010). V 3+ also gives a green colour in beryl (V-rich emerald), as well as in muscovite (Uher et al , 2008; Ertl et al , 2019) and in a number of other minerals and gems (Fritsch & Rossman, 1987).…”

Solubility Product of Vanadinite Pb5(VO4)3Cl at 25 °C—A Comprehensive Approach to Incongruent Dissolution Modeling

“…Vanadinite Pb 5 (VO 4 ) 3 Cl is a secondary mineral, usually found in the oxidation zones of lead deposits and as a product of corrosion of infrastructure. In nature, it is often associated with high V content in mica and clay sediments subjected to hydrothermal processes, occurring under neutral or slightly alkaline conditions [7][8][9]. However, the mineral was also found in lead pipe water systems and it occurs in many already closed lead mines around the world [10,11].…”