What substance is Io surprisingly noted to contain virtually none of, contrasting with its neighbors?
Answer
Water ice
Data suggests Io is the driest known body in the solar system, containing virtually no water ice, which is a surprising fact given the water ice present on moons like Europa.

Related Questions
What feature is absent from Io's surface due to constant resurfacing?What process generates the internal heat that powers Io's intense volcanism?Which Galilean moon is noted as possessing its own internally generated magnetic field?What substance is Io surprisingly noted to contain virtually none of, contrasting with its neighbors?Approximately how frequently is Io's entire surface layer estimated to be replaced?What characteristic defines the surface appearance of Callisto?What astronomical effect locks the Galilean moons into a pattern that influences Io's internal heating?How powerful is the tidal heating energy generated within Io compared to Earth’s internal heat loss?What is the primary feature responsible for Europa being a prime target in the search for extraterrestrial life?What materials are responsible for the orange, red, and yellow colors visible on Io's surface?