This maybe a stupid question. But how did the molten lava cool on mars without any element present to cause that reaction?
Ok, not a stupid question if you are seriously asking. Cooling (or rather heat transfer) occurs anytime there is a temperature differential. Space is cold. The heat radiates out. Mars, being much farther from the sun absorbs much less solar radiation (heat) but the cold space takes all the Martian surface and atmosphere gives off. At some point an equilibrium is reached. On mars, that is well below freezing.