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You could easily come back with 20+ stacks in a short time, but only if you can carry it!
The ore is pretty heavy and only stacks to a meager 100 (you will likely get several stacks per meteor if you're using a decent pick), so be sure to bring a horse and/or bearer if you're aiming for a good haul, as you'll need a lot of follower inventory slots. They don't always disappear when they should and there's sometimes just no way to get at it there should be a bunch of others around that will work! If you're sure you're hitting it and it doesn't crack open after the second try, it's a bug, move on-you're almost certainly not going to get lucky by continuing to try and will just waste explosives. Other items, like the jar, will work in a pinch but are much more cumbersome and expensive to use and don't give you any advantage. Explosive arrows are generally the best choice for the lower weight, cost efficiency (10 per craft), and ease of aiming, but demon fire orbs aren't bad and are often easier to get (need any alchemist thrall at the bench for the recipe to show up).
Yes, every meteor appears with a hardened barrier that can only be broken open for harvesting with an explosive.