I know how you feel. My first functional fort was on Quartzite, because I didn't know any better.
Unless you're going for a major challenge, go for sedimentary (shows up as white letters on the embark screen) plus trees, or else somewhere with a magma pipe (which will generally be igneous extrusive, well, it'll always be IE but there may be other stone layers elsewhere in the region). sedimentary will have lots of iron, and the igneous should have some. Getting a region that has both magma and sedimentary AND trees is pretty much the schist. Bonus points if you get flux (limestone, chalk, dolomite, or marble) as well.
Any fort lacking those things is really going to lack useful military metals. You can melt down captured goblins equipment, but that's really inefficient without magma.
Note that I've found the igneous extrusive rocks appear to have a different vein generation formula than the others. With most rocks each vein seems to have been generated individually based on occurance within the layer, with IE layers it appears the game generates all the veins at once and then choses an ore for them all (or at least, the vast majority). What this means is that I either find vast amounts of iron and not much else, or vast amounts of copper and not much else, or sometimes nothing but a few aluminium clusters.
BTW, this isn't a smelting question.