The 1559 law alots gold and silver, to the miner(s), using the same percentages for both metals. The 1563 law changes those rules and assigns different percentages for each of the two metals. The quintal, or 'quint' is a measure of 100, not a specific numerical percentage. Nowhere in the text of the mining rules have I found a reference to the crown receiving ONLY 20%, except for silver. In fact, it is the miner(s) who in the end recieved the 20%, and that is ONLY after they have made a certain amount of money from an individual mine. The more they took out, the smaller the percentage they got to keep.