Adamantium is the rarest, and strongest mineral in the universe. Only available once you can produce Heavy Cruisers. It is required for the seventh Production Tier. When opening an asteroid mine there is a 40% chance of success (70% for Cleon). Upon success, you gain 1 adamantium production a turn. The price for prospecting starts at 750 GEU and goes up by 250 every successful prospect (for Cleon, goes up by 225).