(Spanish: “royal fifth”), in colonial Spanish America, a tax levied by the crown on mineral products; it was the principal source of profit derived by Spain from its colonies. The percentage was fixed at one-fifth in 1504, to be paid for 10 years, but the rate remained at generally that level until the 18th century. In 1723 the quinto was almost uniformly reduced to the diezmo (one-tenth); in 1777 the rate was everywhere reduced to 3 percent, with 2 percent added to metals on their actual importation into Spain. Although the quinto was officially levied on all mineral production, in practice it was collected only on precious metals and stones.