There was no free oxygen because oxygen reacted to make water, iron, silicates, carbon dioxide, and carbon monoxide.
(oxygen; reacted; to make water, iron, silicates, carbon dioxide, and carbon monoxide) Context(oxygen reacted,List([33, 47))):(oxygen; reacted to make; water, iron, silicates, carbon dioxide, and carbon monoxide)
oxygen reacted,List([33, 47))
oxygen oxygen
reacted reacted to make
to make water, iron, silicates, carbon dioxide, and carbon monoxide
water, iron, silicates, carbon dioxide, and carbon monoxide