Like the Green Martians, White Martians have numerous superhuman powers, including great strength/speed, flight, invisibility, telepathy, shape-changing, phase-shifting (sometimes called variable density) which allows them to be either invulnerably tough or completely immaterial, and "Martian vision", but they also share the Green Martians' vulnerability to fire.
The phase-shifting ability is not depicted in their first post-Crisis appearance [REF].