Chemical and isotopic composition of gas, water, and solids from the 2019-2020 water lake in Halema’uma’u Crater, Kīlauea Volcano, Hawaii: Scanning Electron Microscopy (SEM) of solids filtered from water samples

Samples of the crater lake water were filtered in the field with a 0.45 micron filter. Subsequently, additional precipitates formed in the solute-rich samples (secondary precipitates) which were subsequently filtered in the lab with a 0.45 micron filter. Resulting residues were analyzed both in situ on the filter and after scraping. Samples were sputter coated with 10 nm Au, then imaged in a Tescan VEGA3 scanning electron microscope (SEM) equipped with an Oxford 150 mm2 X-MaxN large area energy dispersive spectrometer at the U.S. Geological Survey, Menlo Park, CA. Elemental backscatter (BSE) images were collected with an accelerating voltage (HV) of 30 kV and a working distance (WD) of ~15 mm. Magnification is indicated on individual images.