Affiliation:
1. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China
2. School of Geosciences and Info-Physics, Central South University, Changsha, Hunan 410083, China
3. State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
5. School of Chemical Engineering, The University of Adelaide, Adelaide, South Australia 5005, Australia
Abstract
Abstract
Jingwenite-(Y), Y2Al2V24+(SiO4)O4(OH)4, the first V-HREE-bearing silicate mineral discovered in nature, is an abundant component of a sediment-hosted stratiform Cu (SSC) deposit, Yushui, South China. The mineral occurs in bedded/massive sulfide-bearing ore and is associated with bornite, chalcopyrite, galena, xenotime-(Y), nolanite, thortveitite, roscoelite, barite, and quartz. Optically, jingwenite-(Y) is biaxial (+), with α = 1.92(4), β = 1.95(2), γ = 1.99(3) (white light), and 2V (calculated) = 83°. The dispersion is medium with r < v, and the pleochroism is with X = light brown, Y = brown, Z = dark brown. The color, streak, luster, and hardness (Mohs) are light brown, yellowish gray, vitreous, and 4½–5, respectively.
Jingwenite-(Y) is monoclinic, with space group I2/a, Z = 4, and unit-cell parameters a = 9.4821(2) Å, b = 5.8781(1) Å, c = 19.3987(4) Å, β = 90.165(2)°, and V = 1081.21(4) Å3. The structure of jingwenite-(Y) has chains of edge-sharing Al(V,Fe)-O octahedra and V(Ti)-O octahedra extending along the b-axis and linked by insular Si-O tetrahedra, leaving open channels occupied by HREEs. Jingwenite-(Y) is a new nesosilicate structural type.
Sm-Nd dating and Nd isotope signatures of jingwenite-(Y) reveal an epigenetic origin and suggest that HREEs and V were added to the SSC system via leaching of abundant heavy minerals in the footwall red sandstone by oxidized basinal brines. The abundance of jingwenite-(Y) at Yushui indicates that it could potentially be a valuable resource for HREE and V. Moreover, HREE and V mineralization can also occur in the same sediment-hosted Cu mineral system.
Publisher
Mineralogical Society of America
Subject
Geochemistry and Petrology,Geophysics
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