What do you need to open the magic mirror doors?

I've come across lots of doors now that are blocked with a kind of mirror on the front and the boy says they are sealed with magic. I have gotten both magic arrorles so I dunno what else I'm missing. What do you need to open the doors locked with the mirror plates?

Wait until you progress further in the game. I wont spoil anything by telling you what it is but it involves a "chisel". The game will push you through a tutorial when the time is right, so there is nothing to worry about for now. Once you have the means to unlock the mirror doors you will know about it.