Hmmm. I know that you can get the different ores from the base rocks if your rates are high enough (10x). I have not played vanilla or really enough to tell you past the fact I found several small nodes that looked brown/grey that gave me silver and iron. Usually up on the top of mountains near gems.
Suzzette is correct. So as it stands now, it is very hard/impossible to play as a solo player because your available engram points do not allow you access to all the trees. I was wondering if it was possible to increase the amount of engram points you get per level