Transmutation (elemental) – The ability to turn an object from one element into another element. Similar to 454) Transmutation (animal), 456) Transmutation (gold), 457) Transmutation (insect), 458) Transmutation (limited), 459) Transmutation (object), 460) Transmutation (organic) and 461) Transmutation (petrification).
Doctor Alchemy (DC) is a supervillain and was originally Mister Element (DC Who’s Who V1 #6).
Mister Element (DC) becomes Doctor Alchemy (DC Who’s Who V1 #15).
Doctor Alchemy uses a Philosopher Stone in DC Heroes-DC Technical Manual.
Element Lad (DC) is a superhero with this power in the 30th century and a member of the Legion of Super Heroes (DC).
Detective Comics #294
Detective Comics V1 #302
Shimmer (DC) is a super villain with this power in DC Who’s Who V1 #20.
Diablo (Marvel) does transmutation the old-fashioned way, through potions in The Official Handbook of the Marvel Universe.