GEO-CM: Trace metals in sphalerite from polymetallic, porphyry-lode mineral deposits of southwest Montana

GEO-CM：来自蒙大拿州西南部多金属斑岩矿床的闪锌矿中的微量金属

• 批准号: 2327676
• 负责人: Christopher Gammons
• 金额: $ 34.5万
• 依托单位: Montana Technological University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2327676&HistoricalAwards=false
• 关键词: GEO; CM; Trace; metals; sphalerite

Sphalerite is the primary ore mineral of zinc, and it oftens contains elevated concentrations of other metals as impurities, many of which are designated as “critical minerals” by the U.S. Geological Survey. Critical minerals include metals that are important to the country’s economy and security, but must currently be imported from other countries. Mines in Butte, Montana are rich in copper, silver, lead, zinc and manganese. The Philipsburg mining district is located 60 km northwest of Butte is smaller but shares many geologic features. Preliminary analyses of sphalerite samples from Butte and Philipsburg show that they are both highly enriched in the critical metals gallium, indium, germanium, and tungsten, as well as copper and silver. Recent research has shown that sphalerite that is richest in these metal impurities fluoresces bright red under a hand-held UV lamp. This phenomenon could provide a low-cost and simple way to sort sphalerite ores with different concentrations of trace metals. The first goal of this study is to analyze samples from Butte and Philipsburg to map out the distribution of metal impurities in sphalerite at the scale of each mining district (several square miles by up to 1 mile deep). The second objective is to make sphalerite grains in the laboratory that contain the same trace metals that are found in the natural specimens. The researchers will then compare the fluorescence behavior of the man-made and natural specimens. This project will train undergraduate and graduate students in the field of economic geology at Montana Technological University (MTU). MTU is a primarily undergraduate institution (PUI) in an EPSCoR state. Results from this project may reveal new ways that sphalerite and other ore minerals can be used to study mineral deposits. This research may also have applications to the use of luminescent sphalerite in materials science and engineering. Butte, Montana is the type example of a zoned, Cordilleran-style, porphyry-lode deposit, as well as being one of the nation’s top historic producers of Cu, Zn, Ag, and Mn. This study will take advantage of the Anaconda Research Lab (ARL) Collection, a set of over 50,000 hand samples collected from Butte and other mines in Montana that is archived at Montana Tech campus. Using the ARL Collection, as well as new samples from the active Continental porphyry Cu-Mo mine, the researchers will assemble a suite of 200 polished ore specimens containing sphalerite and other sulfide minerals from known locations across the entire Butte district, to depths of up to 5000 ft. below the surface. The sphalerite samples will be analyzed by optical microscopy, photoluminescence spectroscopy (PLS), Raman spectroscopy, laser ablation ICP-MS, electron probe microanalysis (EPMA) and hyperspectral cathodoluminescence (HP-CL) to reveal spatial and temporal patterns in trace element distribution, from the micron scale to the km scale. Machine learning tools will be used to identify correlations between elements in the sphalerite database that will help illuminate the underlying mechanisms by which trace elements enter the ZnS structure. For example, the researchers hypothesize that the deep red fluorescence mentioned above is linked to coupled substitution of Cu(+1), Ga(+3), and W(+6) for Zn(+2) in the sphalerite lattice. They will synthesize sphalerite of known trace element compositions using hydrothermal methods and compare the HP-CL, Raman, and PLS signatures of the synthetic and natural specimens. Finally, they will establish collaboration with a synchrotron laboratory capable of using XANES to verify the oxidation state of tungsten and other trace elements in their metal-doped ZnS and natural sphalerite samples. This project will support cutting-edge research and graduate-student training in economic geology at Montana Technological University, formerly the Montana School of Mines, a primarily undergraduate institution (PUI) in an EPSCoR state. Results from this project may reveal new ways that sphalerite and other ore minerals can be used to study mineral deposits, and may have applications to the use of luminescent ZnS in materials science and engineering.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

闪锌矿是锌的主要矿石矿物，通常含有较高浓度的其他金属杂质，其中许多被美国地质调查局指定为“关键矿物”，其中包括对国家经济和安全至关重要的金属。 ，但目前必须从其他国家进口。蒙大拿州巴特的矿藏富含铜、银、铅、锌和锰。菲利普斯堡矿区位于巴特西北 60 公里处，规模较小，但资源丰富。对巴特和菲利普斯堡的闪锌矿样品的初步分析表明，它们都富含关键金属镓、铟、锗和钨，最近的研究表明，闪锌矿的含量最丰富。这些金属杂质在手持式紫外线灯下发出亮红色荧光，这种现象可以提供一种低成本且简单的方法来分选具有不同痕量金属浓度的闪锌矿矿石。这项研究的第一个目标是分析来自比尤特和菲利普斯堡的样品，以绘制出每个矿区规模（几平方英里，深达 1 英里）闪锌矿中金属杂质的分布情况。第二个目标是制造闪锌矿晶粒。然后，研究人员将在实验室中比较人造和天然样本的荧光行为，该项目将培训蒙大拿州经济地质学领域的本科生和研究生。科技大学 (MTU) 是 EPSCoR 州的一所主要本科院校 (PUI)。该项目的结果可能会揭示闪锌矿和其他矿石矿物用于研究矿床的新方法。蒙大拿州巴特 (Butte) 在材料科学和工程中的应用是科迪勒拉式斑岩矿脉矿床的典范，也是美国历史上最重要的矿床之一。这项研究将利用 Anaconda 研究实验室 (ARL) 收集的数据，该收集是从蒙大拿州巴特和其他矿山收集的 50,000 多个手部样本，并存档于蒙大拿州理工学院。 ARL Collection 以及来自活跃的大陆斑岩铜钼矿的新样本，研究人员将组装一套 200 个抛光矿石样本，其中含有闪锌矿和其他已知硫化物矿物将通过光学显微镜、光致发光光谱 (PLS)、拉曼光谱、激光烧蚀 ICP-MS、电子探针微量分析 (EPMA) 对整个 Butte 地区的位置进行分析，深度可达地表以下 5000 英尺。将使用机器学习工具来揭示从微米尺度到公里尺度的微量元素分布的空间和时间模式。确定闪锌矿数据库中元素之间的相关性，这将有助于阐明微量元素进入 ZnS 结构的潜在机制。例如，研究人员发现上述深红色荧光与 Cu(+1) 的耦合取代有关。他们将使用水热法合成已知微量元素成分的闪锌矿，并比较 HP-CL、拉曼和 PLS 特征。最后，他们将与能够使用 XANES 验证金属掺杂 ZnS 和天然闪锌矿样品中钨和其他微量元素的氧化态的同步加速器实验室建立合作。蒙大拿理工大学（原蒙大拿矿业学院）经济地质学研究生培训，该大学是 EPSCoR 州的一所主要本科院校 (PUI)，该项目的结果可能会揭示闪锌矿的新方法。和其他矿石矿物可用于研究矿床，并可能应用于材料科学和工程中发光反射 ZnS 的使用。该奖项是 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的评估进行评估，被认为值得支持。影响审查标准。