Im a little frustrated .. Please help..

My wife and I love playing Eco. Yes, I know, it really gets interesting when you are on a big server with many people. But we just love to play a bit of coop gaming with farming, building and crafting. Now we need Ores for our Research Papers!

We cant find any Ores. We have mined for 6 real hours. Nothing else, just making food and mining. We mined thousends of sone blocks. We concentrated on Desert and Boreal Forests. We mined deep and wide and now are getting a bit frustrated... Do you have any tipps for us finding something? We woukd really appreciate that!