Valheim Black Marble and Iron ingots fast farming in the Mistlands.

Time-efficient Iron Ingots and Black Marble harvesting in Mistlands using viaducts.
Twitch: / aceofbasesca
The final resources from those viaducts totaled 152 Iron (ingots), 21 Copper Scrap, and 1235 Black Marble. Not bad for ~20 minutes. I hope you found it helpful!
valheim-map.world/ Upload your map or use the map seed. Shows locations of various POIs in your world. I've found it very useful as a time-saver.

[@chernobyl169]

Once you reach Ashlands and acquire Flametal, you get a new, more efficient method of harvesting most resources: the Battering Ram. It can destroy rocks, ore nodes, ancient armors and weapons, black marble and grausten structures and more - pretty much anything that isn't a tree or a monster. It also cannot affect terrain, unlike the pickaxe, which makes it ideal for this type of harvesting. It doesn't require a stonecutter or a forge table, only a workbench - and it's wood fired! Don't forget that the Jotun bones yield black marble, too - the ribcages are a great and easy source of black marble but don't yield iron.

[@aceofbasesOG]

I do like the battering ram, but mostly for ruins. Very effective way to break them down for a great amount of Grausten, somewhat quickly. For the viaducts I think the hammer is the way to go because of the ease of tossing down a stonecutter and middle-clicking a few blocks. Sometimes, as in the video, the terrain is much less conducive to wheeling the battering ram around. I play with a few mods as well, so everyone's experience may be different. For Grausten, I break the big rocks with a pickaxe, as I use the TopMining mod. This breaks rocks from the bottom up, so no digging in the terrain. Also, when the rock is broken high enough to clear the dirt, the entire thing collapses with one final hit. It leaves a very clean site, as the ground terrain is left completely untouched. It takes about 4 minutes to break a huge rock completely and yields about 2 stacks more than a full cart and inventory carry. I usually have to run back to bring back the final bits in a second trip. You have definitely made me start thinking about the battering ram vs previously indestructible objects, though. The plains towers? That might be an awesome way to get stone and iron, iirc the contents. Also the plains rock pillars. I'll test those today. Thank you for the tip! Update: The beserker tower is still invincible even to the battering ram. It could've been awesome. As for stone pillars in the plains, I'd forgotten they are normally breakable stone. However, unexpectedly, they also float in the air. I wasn't able to get it to explode from gravity until it was destroyed about halfway up to the top. It also netted only around ~325 stone, which is less than I expected. Good times trying stuff out. Thanks again for the ideas!

[@aceofbasesOG]

I found another viaduct last night in better condition. The final count was 192 iron ingots and 31 stacks of black marble for about 30 minutes of time. Well worth it!

[@frodo9649]

If you remove all the black marble pieces with the hammer, the remaining pieces will fall down much quicker. I also like to launch some fireballs at the middle of the "T" of the iron rebar structure, which also helps with the remaining pieces collapsing faster. And are you sure that damaged pieces drop less parts then ones with full health? Never heard that before, and mining with a pickaxe is also just applying damage to it.

[@aceofbasesOG]

I'm careful not to be too sure of anything when making a video, as things change with patches, mods, etc. I do remember early in my Valheim playing that deconstructing a damaged floor outside in the weather at 50% would return less resources than a floor at 100% from inside. Of course, since then there have been many updates, patches, and I've started using mods like ValheimPlus, which can all affect that equation. I'm pretty certain that at some point I turned on 100% resource return, probably in VPlus, so, in my case, I get everything back. However, I'm presuming that someone who is playing Vanilla might get back less on damaged parts, so I mentioned it and was deliberate to say that I wasn't sure. :) Great tip with the fireballs to hasten the collapse. Thank you for sharing it!