On Mars in the scablands, you can set up an unlimited loot chest chain. Start at the entrance and work your way around the circle. You will find at least 4 chests each circle and occasionally can easily see relic iron poking out of the ground. The rewards are as expected; glimmer, relic iron, and possibly an uncommon item. However, I occasionally will get a rare engram, ship engram, and even strange coins and motes of light. I ran it for about a half hour and had 50+ relic iron and recirved 2 motes of light. Check it out!!!