The Iron dragon looks a bit too much like the Metal dragon for my taste, but hey, gotta have it anyways lol.
Earth Dragon + Metal Dragon = Iron Dragon
And here you can see what I have breeding right now, I think my wait is right around 10 hours. I do have another one in the incubator, so almost done with all of the new goals and dragons ;)
If you want to add me in the game my gamecenter name is prplrush. Feel free to follow my blog for more updates via google friend connect. (right below this post) and google + this post.