Arsenic concentration was investigated in the old and active geothermal indicators.
Very high arsenic content was measured in the reddish-brown deposits.
Yukonite, a rare Ca ferric arsenate hydrous mineral, was identified.
Arsenic concentration in the hydrothermal warm springs ranged from 15,900 to 30,500 μg/L.
High values of As, B, Cs, Fe, Li, Rb, Sb, Si, and Tl are good fingerprints for geothermal source.