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Photo: David Pursehouse from Kawasaki, Japan, CC BY 2.0 via Wikimedia Commons
A highly acidic sulfuric hot spring. In addition to sulfur, the mineral content includes aluminum, iron, and sulfate. The water temperature is 98 °C, and the hot carbonate and hydrogen sulfide gasses that erupt from the springs can be as high as 120 °C.
Unzen Onsen is a geothermally heated volcanic hot spring field in the Unzen Mountains in Nagasaki prefecture in Japan. It was known of for many years, and in the 1910s was developed into a hot spring community because of its many springs. In 1934 the area was designated as the first national park in Japan.
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