There is currently a lack of well‐characterised matrix‐matched reference materials (RMs) for forensic analysis of U‐rich materials at high spatial resolution. This study reports a detailed characterisation of uraninite (nominally UO_2+x) from the Happy Jack Mine (UT, USA). The Happy Jack uraninite can be used as a RM for the determination of rare earth element (REE) mass fractions in nuclear materials, which provide critical information for source attribution purposes. This investigation includes powder X‐ray diffraction (pXRD) data, as well as major, minor and trace element abundances determined using a variety of micro‐analytical techniques. The chemical signature of the uraninite was investigated at the macro (cm)‐scale with micro‐X‐ray fluorescence (µXRF) mapping and at high spatial resolution (tens of micrometre scale) using electron probe microanalysis (EPMA) and laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) analyses. Based on EPMA results, the uraninite is characterised by homogeneous UO₂ and CaO contents of 91.57 ± 1.49% m/m (2s uncertainty) and 2.70 ± 0.38% m/m (2s), respectively. Therefore, CaO abundances were used as the internal standard when conducting LA‐ICP‐MS analyses. Overall, the major element and REE compositions are homogeneous at both the centimetre and micrometre scales, allowing this material to be used as a RM for high spatial resolution analysis of U‐rich samples.

中文翻译：

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Happy Jack Uraninite：用于U富矩阵的高空间分辨率分析的新参考资料

当前，缺乏用于以高空间分辨率对富铀材料进行法医分析的特征明确的基质匹配参考材料（RM）。这项研究报告了尿素的详细表征（标称UO _{2 + x}）（来自美国犹他州的快乐杰克矿）。Happy Jack尿素可作为RM用于测定核材料中的稀土元素（REE）质量分数，这为来源归因提供了关键信息。这项研究包括粉末X射线衍射（pXRD）数据，以及使用各种微分析技术测定的主要，次要和痕量元素的丰度。使用电子探针显微分析（EPMA）和激光消融诱导技术，在宏观（cm）尺度上用微X射线荧光（µXRF）绘图以及在高空间分辨率（数十微米尺度）上研究了尿素石的化学特征。耦合等离子体质谱法（LA-ICP-MS）分析 根据EPMA结果，该铀矿的特征在于均质UO ₂CaO含量分别为91.57±1.49％m / m（2 s不确定度）和2.70±0.38％m / m（2 s）。因此，进行LA‐ICP‐MS分析时，将CaO丰度用作内标。总体而言，主要元素和REE成分在厘米和微米尺度上都是均匀的，因此可以将该材料用作RM，用于富铀样品的高空间分辨率分析。