Crystals of pure native sulfur at sites of degassing called fumaroles

Different sulfur gases, including sulfur dioxide (SO₂) and hydrogen sulfide (H₂S), can react with each other to deposit crystals of pure native sulfur at sites of degassing called fumaroles. The crystals picture here formed within a Sulphur Banks area fumarole in Hawai‘i Volcanoes National Park. USGS photo by T. Elias.