Sand

Sand was a member of the Justice League after the Thanagarian invasion.

Background information
The action figure of this character, released by Mattel in the Justice League Unlimited line has confirmed that this is indeed Sand.

In his comic book history Sanderson Hawkins was the sidekick to the original Sandman, using the name of "Sandy, the Golden Boy". Like Batman's Robin, he was an orphan who was adopted by the hero he fought beside, although Sandy had one prominent surviving relative: Dian Belmont, the Sandman's love interest. Sandy was a member of the Young All-Stars, a team that was later absorbed into the All-Star Squadron. He was later turned into a silicon-based monster by one of his mentor's failed experiments, a "silocoid gun" that exploded and bombarded him with radioactive silica particles. Sandy was kept in suspended animation for many decades while the Sandman searched for a cure. After being turned back to normal by Sandman and the Justice League, Sandy found he had the ability to transform himself into sand as well as other powers over earth derived from his ability to control silica compounds and the generation and control of seismic energy. He changed his codename to Sand, as Sand Hawkins uses a gas mask and 'gas gun' similar to that of his mentor. After Wesley Dodds' death, he also inherited his mentor's prophetic dreams.