Mining skill don´t increase

Hi!
I´m new in the game, i picked minning for my profession, my skill is 55 and I already learned the journeyman, but, no matter how much copper I mine, my skill doesn´t increase (I can only mine copper)
So, you guys know why this happen? Please Help! :D

You can skill up to 100 with Copper Veins. But after 50 skill its green, so it's 1/3 chance to proc skill up.

If you want to increase your mining skill as much as possible, always try to mine orange - yellow colored nodes