Chemical composition (EPMA)

The chemical composition of 28 samples (nos. 1–26, 30, 32) was determined at the Polish Geological Institute—National Research Institute in Warsaw using a Cameca SX-100 electron microprobe (EPMA). The amount of metallic material in sample no. 31 was too small for testing. Therefore, it was excluded from further analyses. Metal samples were obtained using a micro-drill and HSS drills with a diameter of 1–2 mm. Drilling chips or small pieces up to 1.0 mm in length were mounted in epoxy resin in 1-inch discs. Samples were then polished with diamond paste and carbon coated to obtain electrical conductivity. Detailed photographs were taken, using both optical and scanning electron microscopes. Analytical conditions of the EPMA were set to 15 kV of accelerating voltage and 20 nA beam current. The diameter of the electron beam (spot size) was set to 50 μm (samples 1, 3, 4, 5, 18, 19, 20, 24, 25) and 10 μm (2, 6, 7–17, 21, 22, 23, 26, 30, 32), depending on the available homogeneous area of the samples. Due to a variable composition at the μm-scale, approximately 20 areas (15–22) were analysed per each sample. The following standards used and corresponding X-ray lines were used: Si Kα wollastonite, Al Kα orthoclase, S Kα pyrite, Ca Kα wollastonite, Ag Lα hessite, Sb Lα InSb, Sn Lα cassiterite, Cl Kα vanadinite, Bi Mβ Bi2Se3, PbMβ galena, Zn Kα ZnS, Se Lβ ZnSe, As Lβ FeAsS, Cu Kα CuFeS2, Ni Kα Ni metal, Co Kα Co metal, Fe Kα pyrite, Mg Kα diopside, Au Mα Au metal, Hg Mβ cinnabar.

本数据集涵盖28个样品（编号1–26、30、32）的化学成分测试数据，所有测试均于华沙的波兰地质研究所——国家研究院（Polish Geological Institute—National Research Institute）完成，测试仪器为Cameca SX-100型电子探针显微分析仪（EPMA, Electron Probe Micro-Analyzer）。编号31的样品因金属材料含量过低无法开展测试，故被排除于后续分析流程之外。金属样品通过微型钻头及直径1–2 mm的高速钢（HSS, High Speed Steel）钻头钻取获取，钻屑或长度不超过1.0 mm的小块样品被封装于1英寸规格的环氧树脂压片内。随后对样品进行金刚石抛光处理，并通过镀碳工艺赋予其导电性以满足测试要求。研究人员采用光学显微镜与扫描电子显微镜对样品拍摄了详细的形貌照片。电子探针显微分析仪的分析参数设置如下：加速电压15 kV，束流20 nA。电子束斑直径根据样品的可用均匀区域尺寸，分别设置为50 μm（对应样品1、3、4、5、18、19、20、24、25）与10 μm（对应样品2、6、7–17、21、22、23、26、30、32）。鉴于样品在微米尺度下存在成分不均一性，每个样品约选取20个分析区域（范围15–22）开展测试。本次分析所用标样及对应X射线谱线如下：Si Kα：硅灰石（wollastonite），Al Kα：正长石（orthoclase），S Kα：黄铁矿（pyrite），Ca Kα：硅灰石，Ag Lα：碲银矿（hessite），Sb Lα：锑化铟（InSb），Sn Lα：锡石（cassiterite），Cl Kα：钒铅矿（vanadinite），Bi Mβ：硒化铋（Bi₂Se₃），Pb Mβ：方铅矿（galena），Zn Kα：硫化锌（ZnS），Se Lβ：硒化锌（ZnSe），As Lβ：毒砂（FeAsS），Cu Kα：黄铜矿（CuFeS₂），Ni Kα：金属镍，Co Kα：金属钴，Fe Kα：黄铁矿，Mg Kα：透辉石（diopside），Au Mα：金属金，Hg Mβ：辰砂（cinnabar）。