Finally, I found a cave that nobody claimed and I am using my stone axe to mine. But it seems I need more str to mine and for those I can mine I only get stones So how much strength I need to get some iron or copper or any ore?
Copper ore is actually rare. Even 10STR can mine some areas of caves with a 10/10/10 stone axe. I first started getting ore with like 25str or so, but it's a lot to do with luck of how hard that area is.
Bear cape is a great str bonus if you can manage to make one.
Lucky: haven is so quirky Lucky: can be so ugly, can be so heartwarming Sevenless: it is life
Hardness of stone varies from area to area, it's pretty random. I was able to mine my first ore yesterday pretty easily with 36 strength and 13/14/13 stone axe. Hint: prospect above caves, then go see if you can mine any cave tiles near what you find.