I’d recommend looking at this article, where we’ve covered this issue in comparison to several other games.
Just to throw my two cents in, I’m in favor of finite resources underground, but I still sort of like the occasional chance to find some sort of mystic “node” that replenishes itself or provides a small trickle of resources over time (partially because of the ‘city-builder’ focus, if we’re only going to focus on singular-city games for quite a while).
Having the chance to mine ores randomly in stone might also be interesting, but there’d have to be an offset to discourage players from simply strip mining and banking on these chance resources to never have to challenge themselves with other areas for resources or deeper mines.
Lastly, I agree with the larger, rarer veins, but only so when we have the capacity to set up these outer towns and outposts efficiently in Stonehearth’s interface. Stable resource centers will encourage setting up networks of transportation and hauling, which will help the city builder essence in the long run.