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应用多晶X射线衍射和Rietveld拟合和修正测定了含金与无金两类共20个黄铁矿样的精细结构。它们属于空间群T_h~6-Pa3。两类样品的晶胞参数无明显差别,平均值分别为a_0=5.4154(?)和a_0=5.4156(?),而硫原子坐标参数显著不等,含金的(?)_s=0.3849,无金的(?)_s=0.3868。依上述参数计算Fe-S和S-S键长,进而应用键价法算出结构中Fe离子的电价。结果说明含金的黄铁矿中Fe-S键短于五金的,而S-S键则相反;Fe离子价不相等,前者高于后者;大部分矿样中,Fe离子占有率小于1.000。在黄铁矿中容纳着上述离子变价和缺位等非完整性。因此就精细结构而言黄铁矿是一个具有不同程度非完整结构的系列。 含金矿样中Fe离子高于正二价的事实说明,当金以Au~(3+)(Au~+)迁移至含有Fe~(2+)和S_2~(2-)的热液体系中,Fe~(2+)部分地被氧化成Fe~(3+),而Au~(3+)(Au~+)被还原为Au与FeS_2共沉淀下来分散在黄铁矿晶格之外。
The fine structure of 20 pyrite samples, including gold and non-gold, was determined by poly X-ray diffraction and Rietveld fitting and correction. They belong to the space group T_h ~ 6-Pa3. There were no significant differences in the unit cell parameters between the two samples. The average values were a_0 = 5.4154 (?) And a_0 = 5.4156 (?), Respectively, while the sulfur atom parameters were significantly different. (?) _ S = 0.3868. Calculate the Fe-S and S-S bond length according to the above parameters, and then use the bond price method to calculate the Fe ion price in the structure. The results show that the Fe-S bonds in the gold-containing pyrite are shorter than those in the metal, while the S-S bonds are opposite. The ion prices of the Fe ions are not equal, the former is higher than the latter. In most ore samples, the Fe ion occupancy rate is less than 1.000. In the pyrite to accommodate the above-mentioned ion price changes and absence of non-integrity. Pyrite is therefore a series of non-complete structures with different degrees in terms of fine structure. The fact that Fe ions are higher than ortho-divalent in gold-bearing samples shows that when Au migrates from Au ~ (3 +) (Au ~ +) to hydrothermal systems containing Fe ~ (2+) and S_2 ~ (2-) , Fe 2+ is partially oxidized to Fe 3+, and Au 3+ Au 3 + is reduced to co-precipitate with FeS 2 to disperse outside the pyrite lattice.