Geochemical and mineralogical data for mine waste from Sulphur Bank Mercury Mine, Lake County, California

This data release presents geochemical and mineralogical data from mine waste at Sulphur Bank Mercury Mine (SBMM). This work is performed in cooperation with the US Environmental Protection Agency (EPA) to characterize sources of contamination at the SBMM cleanup site. A total of 23 samples were collected: 15 samples were collected by USGS from various waste piles (14 composites from the top 0-5cm of material, and one composite from six discrete ore hand samples), six composite samples were generated from drill cores from monitoring wells installed by EPA contractor EA Engineering, Science, and Technology, Inc., in the waste rock dam in 2022. Two additional hand samples - one cinderblock and one scoria - were collected by USGS from the eastern flank of the South waste pile. The 21 composite samples were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) for trace elements, inductively coupled plasma-optical emission spectroscopy (ICP-OES) for major elements, 5-stage sequential extractions to determine phase associations, semi-quantitative X-ray diffraction (XRD) for mineralogy, and California Arsenic Bioaccessibility (CAB), EPA 1340, and EPA 3051a for total arsenic and relative in vitro arsenic bioaccessibility. The two hand samples were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) for trace elements, inductively coupled plasma-optical emission spectroscopy (ICP-OES) for major elements, and semi-quantitative X-ray diffraction (XRD) for mineralogy. For composite samples, analyses were performed for two size fractions, S4 (63-250 µm) and S5 (< 63 µm), except for CAB, EPA 1340, and 3051a, which were performed on the S3 (< 250 µm) size fraction. The two hand samples were only analyzed for the S5 size fraction. Results are presented for all 23 samples of ore, calcined tailings, waste rock material, waste rock dam drill cores, cinderblock, and scoria collected between 11/20/2020 and 6/17/2022.