Joey Mason is the young son of Rex Mason and Sapphire Stagg. A mutant, he inherited his father's ability to affect nuclear properties; adding or subtracting protons from nuclei. Whereas Rex (aka Metamorpho) can alter the physical properties of his own body, Joey could transmutate the nuclear properties of other objects. Sapphire gave birth to Joey during a time when she was estranged from her husband, and Rex didn't learn of his son's existence for several years. 
His grandfather, Simon Stagg saw Joey as a veritable King Midas who could literally transform lead into gold. He took a personal interest in Joey's well-being and constructed a special nursery for him in his laboratory at Stagg Mansion. When Metamorpho learned that Joey was being kept at Stagg's place, he broke into the laboratory and rescued him. 
Metamorpho had come to discover that the Orb of Ra, the same mystical artifact responsible for giving him his elemental powers, might also hold the key to curing Joey. Along with fellow metamorphae Jillian Conway, Metamorpho brought him all across the globe in search for the Orb, stopping first in Ireland, then Casablanca, and finally back to Egypt. Joey was exposed to radiation from the original meteor responsible for giving Metamorpho his powers and was instantly cured of his condition. 
- Molecular Reconstruction: Joey Mason can alter the protonic makeup of any material, transforming them from one element into another. This involves overcoming the strong nuclear force where protons are removed; and the electromagnetic force where protons are added.
- Joseph Mason is not to be confused with colourist Joey Mason.
- 10 Appearances of Joseph Mason (New Earth)
- 2 Images featuring Joseph Mason (New Earth)
- Quotations by or about Joseph Mason (New Earth)
- Character Gallery: Joseph Mason (New Earth)