Chrysopoeia is the ability to change materials, such as metal, into solid gold by altering their molecular structure at the subatomic level. This ability can be dated back to the days of Greek mythology, as King Midas was also able to turn anything into gold.
Bob, the former leader of The Company after the death of Daniel Linderman, had the ability to turn anything he touched into solid gold. He has used this ability to turn Hampton Connolly, a graphic novel character, into complete gold. It is unknown if it affects the weight of the object. It is also unknown if liquids and gasses can also be turned into solid gold. Bob's ability is not instant when in use, he must concentrate before he can utilize the ability, it will automatically affect anything he comes in physical contact with. It is also unknown if he can revert things back to their original state. He has implied that his ability had greatly improved the financial situation of The Company, when Mohinder mentioned if money could be a problem he said "That won't be a problem. Let's just say we have our own private Fort Knox" while he turned a metal spoon to solid gold.
It is presumed that the effects can be reversed, as Midas from Greek mythology reversed the effects after he turned his daughter into solid gold.