Have you gone below 40F? Obsidian comes from the ore node at 45F, all the way to the left. It's a somewhat rare drop so you might need a few attempts. Just reload. If upgraded you can end up with 9 from a single node. Below it there is a node that gives stardust.
Lost crystal comes from the crystal node at 48F. It's visible from the entry stairs below you. That drop is fairly more rare that obsidian in my experience, dropped as 1 even if improved (not sure even if you could do it anyway, all drops there come out as 1).