How can I break the corrupted rock?
I'm in the corruption, and I noticed that the rock here is indestructible. Why?
The block type I'm facing can't be destroyed
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That is ebonstone and it can only be broken with higher tier pickaxes.
From your screenshot, it looks like you have either an iron pickaxe or a silver pickaxe, neither of which are strong enough to destroy the ebonstone.
It is possible to destroy before you obtain the higher tier pickaxes using one of these methods: