How was Thanos able to destroy the Infinity Stones?

Question

At the beginning of Avengers: Endgame, when the leftover Avengers find Thanos on a planet called "The Garden", we witness the following conversation between them and Thanos,

Natasha: Where are the Stones?

Thanos: Gone, reduced to atoms.

Bruce: You used them two days ago.

Thanos: I used the Stones to destroy the Stones. It nearly killed me. The work is done and always will be. I'm inevitable.

This means that in the current timeline, the Stones are destroyed by Thanos and not recoverable.

Here, what exactly did Thanos do with the Stones? How was he able to do that as he was already weakened by the first snap?

Did he snap again? Did he lose his left ear in that process?

Answer 1

When someone has all 6 stones, they can do "anything" that they want. I put "anything" in quotes because it isn't firmly established what limits may exist on that, though we know that there was something Banner wanted to do with his snap that he wasn't able to.

It is said in the movie that Thanos "used the stones to destroy the stones." This means that yes, he snapped again. We know this from the fact that the energy signature that was detected in the first snap was the same, or very similar, to what happened 21 days later. This is the energy signature given off when the holder of all 6 stones "snaps", using the stones to do whatever they want. In first case, the wish that he made was that half of all living things would go away. In the second case, the wish that he made was that the stones would be reduced to atoms.

It shouldn't matter that Thanos was weakened by the first snap; the stones themselves still had the power to grant the holder anything they want. He says that using the stones the second time "almost killed him"; this could be because he was already weak from the first snap, or it could be because the stones being destroyed gave off a surge of energy that hurt him; we don't know for sure which it is. But it is heavily implied that doing this is why half of his face is damaged.

Answer 2

How was he able to do that as he was already weakened by the first snap?

He destroyed the stones after around 21 days from the first snap. So, he would have recovered a bit from the first snap.

Did he snap again? Did he lose his left ear in that process?

We don't know.

A precedent was clearly established in Avengers: Infinity War, where Scarlet Witch had the power to destroy the Mind Stone. According to Vision, she could do this because her power signature is very similar to the Stone's own. So, one can argue that one can use the stone to destroy it -- which is exactly what Thanos did. How?

So, here goes some speculation:

Thanos would have known how to destroy the stones. And he still had the Infinity Gauntlet. He might have used the Gauntlet to achieve it somehow.

Answer 3

In the comic book it says the stones cannot be used to destroy the stones.

With that said, his first statement is literal, he reduced them down to atoms. His second statement is not literal, he didn't actually destroy the stones, he destroyed the ability to use the stones.