From Wood and Kienle (1990) 
: "Mount Gilbert is a small extinct volcano on northernmost Akun Island. Its northern flank is steep and heavily eroded, presumably by the sea, while its southern flank is little dissected. The summit region has been completely eroded and was presumably north of, and higher than, the present summit. A 20,000 square m zone of slightly older fumarolically altered rock exists 1.5 km northeast of the current summit. Prior to 1948, active fumaroles in this area produced steam plumes visible from a distance; fumarolic activity has since stopped. The altered ground was the site of an unsuccessful attempt to mine sulfur in the 1920's."