Only the skeletons outside will respawn. The only thing that respawns inside are the yellow mushrooms.

As for the minerals, tin will respawn but not the copper.

They seem done once taken/mined.

In the swamps the fire things provide surtling cores, so if you lack burials then you can farm those. Though black forests seem to provide more than enough burial dungeons to get cores from.

Also, always seem to be more than enough copper, tin, silver veins/spots. Iron ore can be a problem if nearby swamps have 0-1 crypts, which can happen. That can be slow going roaming/sailing all over for a swamp with crypts and, of course, stumbling across plains as you sail around or search on foot.

Skeletons will respawn, but not chests and cores.

Nah, they don't come back, but fortunately there's hundreds of tombs and ore veins. The world is huge, so there's always more somewhere. It may be a pain to find it sometimes, but there's always a new stash waiting to be found.

thanks, after spending around 2 hours of exploring west side of my starting point I found 4 clusters of copper veins, I think with those I am done with copper ores all i have left to find is tin ores and more cores for additional coal and ore processor as well as teleporter.

The only thing that respawns inside are yellow mushrooms which make excellent light sources.