All of my worlds seem to have strange errors.
Whenever I embark as Dwarves, I am able to take Ethereal and Slag equipment and tools for 0 dwarfbucks. Once I actually get into the game I dug into a layer of 'Runic', which yielded boulders of 'Runic' that were worth 500 apiece and seemed to drop straight as metal, rather than stone. I also encountered a layer of 'Paralysing' which did not yeald any stone. I also noticed that, in a peat soil layer, there were clusters of 'Thick' (Thats is, just 'Thick', not thick peat, thick soil or thick anything, just 'Thick') which dropped a magma-safe boulder of 'Thick'.
I persisted with my game untill the goblin ambushes arrived, not wearing rusty iron equipment, sporting 'Molten Slag' armor and slag weapons and ammunition. The 'molten slag' armor did not seem to affect them or my dwarves in any way, other than serving as very meager protection.
This bug persisted after I did a clean install to a new folder. These bugs can also be replicated on my friend's machine (we are both running on windows 7 && both downloaded separately from eachother)
EDIT
I reinstalled it again and, this time, I did not change any options in the launcher before playing the game - the bugs above did not occur. (I did not play long enough to test the invaders materials) I will do some tests to find out if any of the options in the launcher cause it.