Rutile is a common mineral in many types of ore deposits and can carry chemical or isotopic information about the ore formation. For closer understanding of this information, the mechanisms of incorporation of minor elements should be known. In this work, we have investigated natural rutile crystals with elevated concentrations of WO3 (up to 17.7 wt%), Cr2O3,tot (7.5), V2O3,tot (4.1), FeOtot (7.3), and other metals. X-ray absorption spectroscopy (XAS) of rutile at the Fe K, Cr K, V K, and W L1 and L3 edges shows that all cations are coordinated octahedrally. The average oxidation state of V is +3.8, and that of Cr is near +4. Shell-by-shell fitting of the W L3 EXAFS data shows that W resides in the rutile structure. Raman spectroscopy excludes the possibility of hydrogen as a charge-compensating species. High-resolution TEM and electron diffraction confirm this conclusion as the entire inspected area consists of rutile single crystal with variable amounts of metals other than Ti. Our results show that rutile or its precursors can be efficient vehicles for tungsten in sedimentary rocks, leading to their enrichment in W and possibly later fertility with respect to igneous ore deposits. Leucoxene, a nanocrystalline mixture of Ti and Fe oxides, is an especially suitable candidate for such a vehicle.

中文翻译：

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钨在含W-Fe-Cr-V的金红石中的掺入机理

金红石是许多类型矿床中的常见矿物，可以携带有关矿石形成的化学或同位素信息。为了更深入地了解此信息，应该知道并入次要元素的机制。在这项工作中，我们研究了WO3（含量高达17.7 wt％），Cr2O3，tot（7.5），V2O3，tot（4.1），FeOtot（7.3）和其他金属浓度升高的天然金红石型晶体。Fe K，Cr K，VK以及W L1和L3边缘的金红石X射线吸收光谱（XAS）表明，所有阳离子都是八面体配位的。V的平均氧化态为+3.8，而Cr的平均氧化态接近+4。W L3 EXAFS数据的逐壳拟合表明W驻留在金红石结构中。拉曼光谱法排除了氢作为电荷补偿物质的可能性。高分辨率TEM和电子衍射证实了这一结论，因为整个检查区域均由金红石型单晶组成，其中除了Ti以外的金属含量也有所变化。我们的结果表明，金红石或其前驱体可能是沉积岩中钨的有效载体，从而导致其富集了W，并可能在以后的火成岩矿床中具有生育能力。Leucoxene是Ti和Fe氧化物的纳米晶混合物，是这种载体的特别合适的候选物。