Where can i find copper?

[Nezuko]

Hello everyone, I'm kinda stuck I have unlocked the idea for obsidian tools and trying to unlock copper tools to upgrade my water bucket so that i can get the automatic watering system. Does anybody know where it is?

[Totto]

There is more to unlocking Irrigation then Copper ^^
But you need to progress deeper into the Mines, Copper starts appearing to rooms to the West of "Stomp your Feet", just have a look at one of the guides, you can see it more clearly there :-P