Each campaign will have 24 mines that spawn across the map: two mines per adventure zone and four mines per wildland zone. Different mines will spawn either timber, ingots, or boulders, which can be collected from five resource chests that respawn every hour in random places in a mine in order to prevent camping.
Content retrieved from: https://massivelyop.com/2021/11/06/crowfalls-7-300-update-will-introduce-mines-full-of-resources-to-collect/.