I’ll address the Elder Wand first.
This was possible in the movie, but I don't believe this occured in the books.
You’re right: in the books, Harry returns the Elder Wand to Dumbledore’s tomb. (He reasons that if he dies a natural death, then the wand’s power will die with him. He never discusses whether breaking the wand is possible or practical.)
There are two other instances of wands being broken:
In Chamber of Secrets, Ron’s wand is broken by the Whomping Willow.
In Order of the Phoenix, Neville’s wand is broken by Dolohov in the battle at the Ministry, when the Death Eater breaks his nose and his wand.
And here are some other instances of magical items being damaged by excessive force:
In Prisoner of Azkaban, when Harry’s broomstick encounters the Whomping Willow.
In Order of the Phoenix, when hundreds of prophecies are smashed on the floor of the Ministry.
In Deathly Hallows, somebody remarks that Harry’s invisibility cloak is remarkably damage resistant – most would fade or tear, but his hasn’t. This implies that a normal invisibility cloak suffers wear-and-tear, and might be damaged by excessive force.
At a stretch, you could argue that people are magical items (at the very least, powerful ones like Dumbledore or Voldemort), but both of them would break if enough force was applied.
So the answer to the original question is probably not.
However, I think some of these examples give a hint at a refinement. (Here ends fact and begins speculation.)
We're told that the Elder wand is stolen from its first owner in his sleep. Its power isn't being used when it's stolen, so the fact that it was a highly magical object (and an invincible wand) didn't matter, because its magic wasn’t in play. If you tried to fight the owner in a duel, you’d probably lose, but not if you try to pickpocket what is essentially a wooden stick.
The prophecies explain this better. I think it would be quite difficult to “destroy” the prophecy (whatever that means – perhaps erasing all knowledge of it?), and the glass sphere is just a repository for it. You can destroy the container, but not the enclosing object.
People have similar properties: if we count the soul as being somewhat immaterial (if not actually magical), then we notice that destroying the body (the container) doesn’t destroy the soul itself. Of course, this falls apart if you mention horcruxes.
So I'd suggest something like the following: a magical item has excessive strength when its magic is used, but its container is as fragile as a non-magical object. But that's just a guess.