A multi-methodical characterization of a sauconite (Zn-bearing trioctahedral smectite) specimen from the Skorpion ore deposit (Namibia) was performed by combining X-ray powder diffraction (XRPD), cation exchange capacity (CEC) analysis, differential thermal analysis (DTA), thermo-gravimetry (TG), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM-HRTEM-AEM). The X-ray diffraction pattern exhibits the typical features of turbostratic stacking disorder with symmetrical basal 00l reflections and long-tailed hk bands, as confirmed by TEM observations. Besides sauconite, the sample contains minor amounts of kaolinite, dioctahedral smectite, and quartz. CEC analysis provides a total of Ca (~69%), Mg (~26%), Na (~4%), and K (0.7%) exchangeable cations. Therefore, Zn is located exclusively within the octahedral site of sauconite. TG analysis of the sample yields a total mass loss of about 17%. Three endothermic peaks can be observed in the DTA curve, associated with dehydration and dehydroxylation of the material. An exothermic peak at 820 °C is also present as a consequence of decomposition and recrystallization. The infrared spectrum shows the typical Zn3OH stretching signature at 3648 cm–1, whereas, in the OH/H2O stretching region two bands at 3585 and 3440 cm–1 can be attributed to stretching vibrations of the inner hydration sphere of the interlayer cations and to absorbed H2O stretching vibration, respectively. Diagnostic bands of kaolinite impurity at ~3698 and 3620 cm–1 are also found, whereas 2:1 dioctahedral layer silicates may contribute to the 3585 and 3620 cm–1 bands. Finally, using the one-layer supercell approach implemented in the BGMN software, a satisfactory XRPD profile fitting model for the Skorpion sauconite was obtained. These findings have implications not only for economic geology/recovery of critical metals but also, more generally, in the field of environmental sciences.

中文翻译：

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通过多方法学方法从Skorpion锌矿床（纳米比亚）中获取锌蒙脱石（锌蒙脱石）的晶体化学的新见解

通过结合X射线粉末衍射（XRPD），阳离子交换容量（CEC）分析，差热分析（​​DTA）对Skorpion矿床（纳米比亚）中的锌蒙脱石（含锌三八面体蒙脱石）标本进行了多方法表征），热重法（TG），傅里叶变换红外光谱（FTIR）和透射电子显微镜（TEM-HRTEM-AEM）。X射线衍射图显示出具有对称的基础00l反射和长尾hk波段的涡轮层堆积紊乱的典型特征，这已被TEM观测所证实。除了锌蒙脱石，样品还包含少量的高岭石，二八面体蒙脱石和石英。CEC分析提供了总计的Ca（〜69％），Mg（〜26％），Na（〜4％）和K（0.7％）可交换阳离子。所以，锌仅位于锌蒙脱石的八面体位点内。样品的TG分析得出总质量损失约为17％。在DTA曲线中可以观察到三个吸热峰，与材料的脱水和脱羟基有关。分解和重结晶的结果是在820°C出现放热峰。红外光谱显示在3648 cm-1处典型的Zn3OH拉伸特征，而在OH / H2O拉伸区域中3585和3440 cm-1处的两个谱带可归因于层间阳离子内部水化球的拉伸振动和分别吸收H2O拉伸振动。还发现了高岭石杂质的诊断谱带，约为3698和3620 cm-1，而2：1二八面体层硅酸盐可能会影响3585和3620 cm-1。最后，使用在BGMN软件中实现的单层超级电池方法，可以获得令人满意的Skorpion锌蒙脱石的XRPD轮廓拟合模型。这些发现不仅对经济地质/关键金属的回收有影响，而且在环境科学领域更具有普遍意义。