Liguowuite, WO3, a new member of the A-site vacant perovskite type minerals from the Panzhihua-Xichang region, China

Authors：Xue, Yuan^*; Sun, Ningyue; He, Hongping; Chen, Aiqing; Yang, Yiping

Source：European Journal of Mineralogy, 2022, 34(1): 95-108.

DOI：10.5194/ejm-34-95-2022

• CRYSTAL-STRUCTURE
• TUNGSTEN-OXIDE
• PHOTOCHROMIC PROPERTIES
• SENSING PROPERTIES
• NOMENCLATURE
• PARAMETERS
• SURFACE
• FILMS

A new member of the non-stoichiometric perovskite group mineral species, liguowuite, ideally WO3, has been found in the Neoproterozoic Sinian biotite-quartz monzonite in the southern part of the Panzhihua-Xichang region (Nanyang village: 26 degrees 46'08.21 '' N, 101 degrees 27'13.86 '' E), China. It is associated with hornblende, pargasite, ferro-hornblende, annite, hydrobiotite, phlogopite, orthoclase, microcline, albite, quartz, kaolinite, ilmenite, goethite, hematite, magnetite, pyrite, zircon, zoisite, titanite, epidote, diopside, tourmaline, almandine, fluorapatite, monazite-(Ce), allanite-(Ce), bastnasite-(Ce), xenotime-(Y), scheelite, moissanite, tellurite, wumuite, and tewite. Liguowuite occurs as greenish yellow prisms, ranging from 0.05 to 0.1 mm in diameter, and it is transparent with a greasy luster and a white streak. Liguowuite exhibits a triclinic pseudomorphism composed of nanoparticles with many cracks and nanovoids. This mineral is brittle and has a Mohs hardness value of approximately 3-4. The calculated density is 7.22 g cm(-3). Electron microprobe analyses gave (average weight percent, wt %, of 15 spot analyses of 4 samples) K2O = 0.01, WO3 = 99.23, TeO2 = 0.03, CaO = 0.06, Na2O = 0.04, and total 99.37, yielding the empirical formula W1.00O3, based on O-apfu = 3 and ideally WO3. The strongest five diffraction lines (d angstrom (I)(hkl)) are 3.8552 (88)(002), 3.7685 (88)(020), 3.6590 (100)(-200), 2.6928 (43)(022), and 2.6258 (60)(202). Liguowuite is monoclinic and is in space group P2(1)/n, with a = 7.32582(18) angstrom, b = 7.54767(18) angstrom, c = 7.71128(18) angstrom, beta = 90.678(3)degrees, V = 426.348(19) angstrom(3), and Z = 8. The crystal structure data were refined using the Rietveld refinement method and X-ray powder diffraction data. The reliability factors (R factors) were R-wp = 0.0604 and R-p = 0.0454, with chi(2) = 1.707. Liguowuite consists of corner-sharing distorted and tilted [WO6] octahedra, in which the W atoms are off-center and form six W-O bonds ranging from 1.7 to 2.2 angstrom with the surrounding oxygen atoms. According to the hierarchical scheme for perovskite supergroup minerals, liguowuite is the first reported example of A-site vacant single oxide, i.e., a new perovskite subgroup.

• Institution
  y; 中国科学院