That wasn't his fault, it was mine.

那不是他的错，是我的错。

《柯林斯英汉双解大词典》

And he know that it was mine.

知道那是我种下的果实。

youdao

With a shock, I realized it was mine.

我震惊地意识到，那声尖叫是我自己发出的。

youdao

It was used for an oil well or gold mine that had almost no oil or gold in it.

VOA: special.2009.11.08

The Homestake Gold Mine was chosen to study dark matter because it is largely protected from the radiation that could interfere with the project.

VOA: special.2009.07.21

There is a Spanish phrase, using the feminine article that says: "I broke it because it was mine".

BBC: Domestic violence (posed)

It was a fascinating detail, and it was mine, not his, which meant that he would let it pass without comment.

NEWYORKER: Midnight in Dostoevsky

But it was mine if I wished, simply because I was the last person with the power to do anything with it.

NPR: 'Ancestor Stones:' Life and War in Sierra Leone