The ones in Patriarch cave are just before you meet him, right before the wooden walkway. I had two veins, not sure if it's random or not.
One on the right hand side next to a wooden mine brace was easy to see and only had one gem. The other is tucked away in a little pocket area on the left back behind that wagon I believe it was and had two malachite gems. It's hard to see you need to be virtually on top of it as it's down in a little pocket in the rocks.
