Cover photograph Surface and underground features in the Okuaizu geothermal system, Fukushima, Japan. Arsenic sulfide containing sub-ppm Au (orange in colour) precipitated in lacustrine sediments near present hot spring discharge (upper left), CO2 and H2S gas bubbles from river water along one of fracture zones (upper right), molten sulfur (amber in colour) recovered from geothermal fluid (lower left) and Anhydrite (Anh), sphalerite (Sp), pyrite (Py) and quartz (Qz) precipitated from geothermal fluid on surface of reservoir fracture (lower right). (Photo and text by Yoji SEKI, Research Center for Deep Geological
Environments, GSJ)
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