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). The solids that accumulated on the filters (both secondary and original precipitate) were digested by heating overnight in a sealed Teflon vial with 300 µL concentrated HCl, 100 µL concentrated HNO3, and 500 µL concentrated HF. Following digestion, samples were dried down, then re-dissolved in 300 µL concentrated HNO3 and diluted with MilliQ water. The liquid from the digested samples were analyzed for element concentrations by inductively coupled plasma-optical emission spectrometry (ICP-OES) using a ThermoFisher ICAP 6500 Duo at the U.S. Geological Survey laboratories in Menlo Park, California.