means A pit, tunnel, or excavation dug into the earth to extract coal, ore, gems, or other minerals — or the act of digging one.

from From Old French 'mine' (a vein of ore, an underground passage), which passed into Middle English; its deeper roots are murky, possibly Celtic — Gaulish gives us something like 'meina' for ore, and there are Celtic cousins meaning 'metal' or 'mineral.' The military 'mine' — the buried, exploding kind — grew from the same digging word: sappers once tunneled under enemy walls to collapse them, so 'mining' came to mean undermining, then the charge itself. The homophone 'mine' meaning 'belonging to me' is entirely unrelated, descending from Old English 'min' — same family as 'me.'