Board Thread:General Discussion/@comment-24909740-20140506160416/@comment-24821572-20140506193752

Well, I'm not sure about the size of the corruption it spawns, but they are random. Add that together with the alacrity of corruption spreading in hardmode, powders are not the way to go. My advice is that you only break 3 of them to spawn the 3 types of ores, and no more than that. Use spelunker to help you locate the ores. Once you believe you can take on Destroyer(easiest mecha) with new hardmode weapons and armors, summon it and kill it to have Steampunker move into one of your free houses. After which you have access to one of the most expensive weapon(lol) in the game, the Clentaminator, that costs 2 platinum for itself and 25 silver each for one of its ammo(solutions). If you still want more of the ores, you can break more altars. With the Clentaminator,  preventing them from getting out of control should be easy.

As for them corrupting jungle, they will turn mud blocks into corrupted/hallowed dirt blocks. Once you purify them, they will unfortunately stay as dirt blocks, but still part of the jungle(I can't confirm this actually but it says so on the page).