By physical logic, fire doesn't exist as mass, and therefore would still leave water behind in the form of steam.
True Elements however, do not abide by negation logic and when equal parts of a true element come together they do not negate. In fact, all 4 true elements (earth, fire, water, and air) combined actually form Orichalcum. One might posit that this orichalcum is the same as the orichalcum found naturally during the Year of the Comet. Interestingly enough, radical mercury, copper, gold, and silver also form Orichalcum. Interesting, no?