I'm currently working on a Sci-Fi setting for my friends to use in a campaign (my friend is GM but he's too lazy to come up with a setting so I offered to do it), I've already worked out the minor details (like, what the aliens look like, history, weaponry, etc.) but I keep running into one problem.
The setting relies upon hard Sci-Fi (AKA the exact opposite of the BS that is Star Trek) and I can't find/create a Hard Sci-Fi explanation for this material.
The material I'm trying to explain is (in normal circumstances) completely indestructible (It's not absolutely indestructible, like if you threw it into a black hole it would absolutely be destroyed). Here are the criteria this material has to meet.
1: Material must be near indestructible (methods for destruction could involve throwing it into a black hole or shoving it into the core of a sun).
2: The Material must be extremely valuable (valuable enough for wars to be fought over it)
3: Material must be able to interact with regular matter
4: A nuclear detonation should not be capable of destroying this material... entirely (dropping a nuke directly on top of this material would put it into a Liquid state)
So my question is... How could I scientifically explain a near indestructible super material without having to make it's existence one big handwave?