Powers: The three weilders of the Blackrock seem to have developed differing powers based on their personality. All seem to have possessed superhuman strength and endurance, flight and energy projection abilities. The Blackrock also has the ability to absorb ambient energy to empower its wielder. Dr. Silverstone seemed most adept at using its ability to process information from TV and radio signals.
Bio: Blackrock was the creation of Dr. Peter Silverstone in an attempt to increase ratings for the United Broadcasting television network. Silverstone hypnotized UB President Sam Tanner and later Tanner's nephew, Les Vegas, to fill the role. Later Silverstone assumed the mantle of Blackrock himself, using a powerful stone that could metabolize electromagnetic energy into energy to achieve flight, energy blasts and superhuman strength, and fought Superman several times. This rock, while a technological artifact, has the appearance of a polished gem that is black as coal. It was appropriately dubbed the "Blackrock".
Overuse of the powers blinded Silverstone and left him insane. He was found sitting muttering to himself and watching constant television in an apartment by an ex-convict named Sam Benjamin, who beat Silverstone to death with the rock and took it for himself. Despite its power, his inexperience with the stone led to his defeat, and Superman took the stone and threw it towards the Sun.