I just came up with an idea - Uranium. I know there isn't much chemistry in Minecraft, and it could be fun. I know many would think it's uneccesary, "we have TnT", but it also be used in other cases. Maybe to make power for electricity?
Uranium would be extremly rare. In bombs, it could make radioactivity(?).
We could for example have ...
Put Uranium in the reactor to make energy. Nuke
Where is Uranium and is the Reactor
The nuke is extremly powerful. Technology
Don't know, maybe like chemistry or something?