Small acidic hot spring in the Gibbon Geyser Basin of Yellowstone National Park

An unnamed small acidic (pH ~3) hot spring (with a temperature of about 55°C at the source) in the Gibbon Geyser Basin of Yellowstone National Park. The yellow region is due to the precipitation of sulfur by sulfide-oxidizing chemotrophic microorganisms. The presence of phototrophic microorganisms (here mostly algae) is indicated by the bright blue-green chlorophyll pigments.