Originally posted by Honor Guard:

The copper nodes for those whom don't know,tend to spawn in a sphere style shape (more disc) with a semi hollow (Filled with dirt) interior

How would you like them to spawn?

The nodes are actually solid all the way through but the game engine allows ore and dirt to occupy the same space. So when you break a big piece of ore off with your pick it reveals the dirt that was occupying the space the ore was previously in.