Abstract
Abstract Mineral phases in which vanadium (V) and heavy-rare-earth elements (HREEs) coexist are rarely documented. Here, we report a new V-HREE-bearing silicate mineral species, wenlanzhangite-(Y), which is a vanadiferous derivate of jingwenite-(Y) [Y2Al2V24+(SiO4)2O4(OH)4] coexisting with jingwenite-(Y) in bedded/massive ores at Yushui, South China. Wenlanzhangite-(Y) forms as a dark brown, 70–100 μm thick rim on a core domain of jingwenite-(Y), which occurs as 100–200 μm columnar crystals. The color, streak, luster, and hardness (Mohs) are dark brown, yellow-gray, vitreous, and ~4, respectively. Compared to jingwenite-(Y), wenlanzhangite-(Y) has higher vanadium and lower aluminum contents. Calculated on the basis of 8 cations, the empirical formula is (Y1.26Dy0.17Er0.11 Gd0.09Yb0.09Nd0.09Sm0.06Sc0.04Ho0.03Ce0.02Tb0.02Tm0.02Pr0.01)Σ2.00(V1.463+Al0.54)Σ2.00V24+(SiO4)2O4(OH)4, which can be simplified to the ideal formula Y2V23+V24+(SiO4)2O4(OH)4. Wenlanzhangite-(Y) is triclinic, with space group P1(#2), Z = 2, and unit-cell parameters a = 5.9632(7) Å, b = 9.599(1) Å, c = 9.9170(9) Å, α = 90.033(8)°, β = 98.595(2)°, γ = 90.003(9)°, and V = 561.28(10) Å3. Wenlanzhangite-(Y) is approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2022-142). The structure of wenlanzhangite-(Y) is composed of a-axis-oriented chains of [VO6] octahedra consisting of edge-sharing octahedra linked by insular [SiO4] tetrahedra, leaving open channels occupied by rare earth elements. Observed compositional variation and crystal structure demonstrate that V3+ can substitute for Al3+ in jingwenite-(Y), forming wenlanzhangite-(Y). The occurrence of wenlanzhangite-(Y) indicates a relatively more reducing hydrothermal environment, causing a reduction of V5+ in oxidized fluids to V3+ and thus represents a useful proxy for tracing the redox state of ore formation.
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