I don’t know, how to leave stone age legitimately. To make crucible and other stuff I need chisel. The only recipe for chisel tool uses steel (well, I’m lucky boy and found 5 steel ingots on an island in the ocean, where my spawnpoint is). Another way - making bronze multitool (which has chisel head, so it should be possible to use (and yes, I am lucky boy *2, cause I found bronze ingots too. I guess, I could find some resources in mineshafts too)). But what should I use, if I were not as luck as I am right now? For making steel/bronze I need to get steel/bronze first.
P.S. I read wiki guide, FAQ and changelog, but I’m still confused about it.