First, you have to get the mining skill. You can't mine without knowing how to mine right?
Go to Ases in Belos just before the exit of the town.
NOTE: You'll get a quest from her, but you have to get level 7 to get it, okey?
Talk to her and accept the "learn the mining skill".

Spoiler!

This is the quest.

To finish this quest you'll need to kill 10 Ugly dogs and 10 Gray beetle G. To get  Latale Ely, you have to go to the forest mine and to get to the forest mine you have to go through the Forest Area and go the the Ancient Forest. Take the first upper portal and then take the next portal, Voilá. You're in the forest mine!

Spoiler!

Now you'll have to go and find the Gray Beetle G and the Ugly Dog.

The first level of the forest mine will only Contain some weird rocks with a blue and pink crystal inside. I'll come back to them later on. You should go to the second level.
On the second level will the Gray Beetle G be. they are just like the normal Beetle G, only a bit stronger. So don't worry so much about them, but I hope you brought a bunch of potions before going to the forest mine. If not, run back and get Latale Ely. If you've killed 10 Gray Beetle Gs go on to the third level of the mine.
Don't worry here, There is no monsters here. However, there is a Iris stone here, so be sure to go and save on that, in case you die. On the forth level the Ugly dog will pop up. He's just like the Wild Dog, Just a bit stronger. Kill ten of those and you're done! God job! Now go to Ases and collect your skill!

A Grey Beetle G and a Ugly dog.

Now that you've got your mining skill you'll able to go to the forest mine and mine minerals!
You should be searching for these:
These stones will drop different kind of minerals, just choose a hot key to place your Mining skill on, walk up to hit and press and hold the hot key for your mining skill. You're mining!
These stones have 26 HP and you will deal about 1-2 damage. So it won't take so long to get  what you want. Alla the stones will drop different typ of Minerals, for exempel Silver, Latale Ely, Iron ect. Go and mine to discover all the minerals.

The stones are located all over the mine, Except for level 2 and 4.